Copyright Page

Chapter 1. Configuring GLBP

Finding Feature Information

Prerequisites for GLBP

Restrictions for GLBP

Information About GLBP

GLBP Overview

GLBP Active Virtual Gateway

GLBP Virtual MAC Address Assignment

GLBP Virtual Gateway Redundancy

GLBP Virtual Forwarder Redundancy

GLBP Gateway Priority

GLBP Gateway Weighting and Tracking

GLBP Client Cache

GLBP MD5 Authentication

ISSU-GLBP

GLBP SSO

GLBP Benefits

How to Configure GLBP

Enabling and Verifying GLBP

Customizing GLBP

Configuring GLBP MD5 Authentication Using a Key String

Configuring GLBP MD5 Authentication Using a Key Chain

Configuring GLBP Text Authentication

Configuring GLBP Weighting Values and Object Tracking

Troubleshooting GLBP

Configuration Examples for GLBP

Example: Customizing GLBP Configuration

Example: Configuring GLBP MD5 Authentication Using Key Strings

Example: Configuring GLBP MD5 Authentication Using Key Chains

Example: Configuring GLBP Text Authentication

Example: Configuring GLBP Weighting

Example: Enabling GLBP Configuration

Additional References for GLBP

Feature Information for GLBP

Glossary

Chapter 2. HSRP Version 2

Finding Feature Information

Information About HSRP Version 2

HSRP Version 2 Design

How to Configure HSRP Version 2

Changing to HSRP Version 2

Configuration Examples for HSRP Version 2

Example: Configuring HSRP Version 2

Additional References

Feature Information for HSRP Version 2

Chapter 3. FHRPâ€”HSRP BFD Peering

Finding Feature Information

Restrictions for FHRPâ€”HSRP BFD Peering

Information About FHRPâ€”HSRP BFD Peering

HSRP BFD Peering

How to Configure FHRPâ€”HSRP BFD Peering

Configuring BFD Session Parameters on an Interface

Configuring HSRP BFD Peering

Verifying HSRP BFD Peering

Configuration Examples for FHRPâ€”HSRP BFD Peering

Example: HSRP BFD Peering

Additional References for FHRPâ€”HSRP BFD Peering

Feature Information for FHRPâ€”HSRP BFD Peering

Chapter 4. FHRP - HSRP Group Shutdown

Finding Feature Information

Information About FHRP - HSRP Group Shutdown

How Object Tracking Affects the Priority of an HSRP Device

HSRP Object Tracking

HSRP Group Shutdown

How to Configure FHRP - HSRP Group Shutdown

Configuring HSRP Object Tracking

Configuring HSRP MD5 Authentication Using a Key String

Configuration Examples for FHRP - HSRP Group Shutdown

Example: Configuring HSRP Object Tracking

Example: Configuring HSRP Group Shutdown

Additional References

Feature Information for FHRP - HSRP Group Shutdown

Chapter 5. FHRP - HSRP MIB

Finding Feature Information

Information About FHRP - HSRP MIB

HSRP MIB Traps

How to Configure FHRP - HSRP MIB

Enabling HSRP MIB Traps

Configuration Examples for FHRP - HSRP MIB

Example: Enabling HSRP MIB Traps

Additional References

Feature Information for FHRP - HSRP-MIB

Chapter 6. HSRP MD5 Authentication

Finding Feature Information

Information About HSRP MD5 Authentication

HSRP Text Authentication

HSRP MD5 Authentication

How to Configure HSRP MD5 Authentication

Configuring HSRP MD5 Authentication Using a Key Chain

Troubleshooting HSRP MD5 Authentication

Configuring HSRP Text Authentication

Configuration Examples for HSRP MD5 Authentication

Example: Configuring HSRP MD5 Authentication Using Key Strings

Example: Configuring HSRP MD5 Authentication Using Key Chains

Example: Configuring HSRP MD5 Authentication Using Key Strings and Key Chains

Example: Configuring HSRP Text Authentication

Additional References

Feature Information for HSRP MD5 Authentication

Chapter 7. HSRP Support for ICMP Redirects

Finding Feature Information

Information About HSRP Support for ICMP Redirects

HSRP Support for ICMP Redirect Messages

ICMP Redirects to Active HSRP Devices

ICMP Redirects to Passive HSRP Devices

ICMP Redirects to Non-HSRP Devices

Passive HSRP Advertisement Messages

ICMP Redirects Not Sent

How to Configure HSRP Support for ICMP Redirects

Enabling HSRP Support for ICMP Redirect Messages

Configuration Examples for HSRP Support for ICMP Redirects

Example: Configuring HSRP Support for ICMP Redirect Messages

Additional References

Feature Information for HSRP Support for ICMP Redirects

Chapter 8. HSRP Support for MPLS VPNs

Finding Feature Information

Information About HSRP Support for MPLS VPNs

HSRP Support for MPLS VPNs

Additional References

Feature Information for HSRP Support for MPLS VPNs

Chapter 9. FHRP - HSRP Multiple Group Optimization

Finding Feature Information

Information About FHRP - Multiple Group Optimization

HSRP Multiple Group Optimization

How to configure FHRP - Multiple Group Optimization

Configuring Multiple HSRP Groups for Load Balancing

Improving CPU and Network Performance with HSRP Multiple Group Optimization

Configuration Examples for FHRP - Multiple Group Optimization

Example: Configuring Multiple HSRP Groups for Load Balancing

Example: Improving CPU and Network Performance with HSRP Multiple Group Optimization

Additional References

Feature Information for FHRP - HSRP Multiple Group Optimization

Chapter 10. Configuring IRDP

Finding Feature Information

Information About IRDP

IRDP Overview

How to Configure IRDP

Configuring IRDP

Configuration Examples for IRDP

Example: Configuring IRDP

Additional References

Feature Information for IRDP

Chapter 11. Configuring VRRP

Finding Feature Information

Restrictions for VRRP

Information About VRRP

VRRP Operation

VRRP Benefits

Multiple Virtual Router Support

VRRP Router Priority and Preemption

VRRP Advertisements

VRRP Object Tracking

How Object Tracking Affects the Priority of a VRRP Router

VRRP Authentication

In Service Software Upgrade--VRRP

VRRP Support for Stateful Switchover

How to Configure VRRP

Customizing VRRP

Enabling VRRP

Disabling a VRRP Group on an Interface

Configuring VRRP Object Tracking

Configuring VRRP MD5 Authentication Using a Key String

Configuring VRRP MD5 Authentication Using a Key Chain

Verifying the VRRP MD5 Authentication Configuration

Configuring VRRP Text Authentication

Enabling the Router to Send SNMP VRRP Notifications

Configuration Examples for VRRP

Example: Configuring VRRP

Example: VRRP Object Tracking

Example: VRRP Object Tracking Verification

Example: VRRP MD5 Authentication Configuration Using a Key String

Example: VRRP MD5 Authentication Configuration Using a Key Chain

Example: VRRP Text Authentication

Example: Disabling a VRRP Group on an Interface

Example: VRRP MIB Trap

Additional References for Configuring VRRP

Feature Information for VRRP

Glossary

Chapter 12. VRRPv3 Protocol Support

Finding Feature Information

Restrictions for VRRPv3 Protocol Support

Information About VRRPv3 Protocol Support

VRRPv3 Benefits

VRRP Device Priority and Preemption

VRRP Advertisements

How to Configure VRRPv3 Protocol Support

Enabling VRRPv3 on a Device

Creating and Customizing a VRRP Group

Configuring the Delay Period Before FHRP Client Initialization

Configuration Examples for VRRPv3 Protocol Support

Example: Enabling VRRPv3 on a Device

Example: Creating and Customizing a VRRP Group

Example: Configuring the Delay Period Before FHRP Client Initialization

Example: VRRP Status, Configuration, and Statistics Details

Additional References for VRRPv3 Protocol Support

Feature Information for VRRPv3 Protocol Support

Glossary

Chapter 13. VRRPv3: Object Tracking Integration

Finding Feature Information

VRRP Object Tracking

How VRRP Object Tracking Affects the Priority of a Device

Tracking an IPv6 Object using VRRPv3

Example: Tracking an IPv6 Object using VRRPv3

Example: Verifying VRRP IPv6 Object Tracking

Additional References for VRRPv3: Object Tracking Integration

Feature Information for VRRPv3: Object Tracking Integration

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Chapter 1. Configuring GLBP

Gateway Load Balancing Protocol (GLBP) protects data traffic from a failed device or circuit, like Hot Standby Router Protocol (HSRP) and Virtual Router Redundancy Protocol (VRRP), while allowing packet load sharing between a group of redundant devices.

- Finding Feature Information

- Prerequisites for GLBP

- Restrictions for GLBP

- Information About GLBP

- How to Configure GLBP

- Configuration Examples for GLBP

- Additional References for GLBP

- Feature Information for GLBP

- Glossary

Finding Feature Information

Your software release may not support all the features documented in this module. For the latest caveats and feature information, see Bug Search Tool and the release notes for your platform and software release. To find information about the features documented in this module, and to see a list of the releases in which each feature is supported, see the feature information table.

Use Cisco Feature Navigator to find information about platform support and Cisco software image support. To access Cisco Feature Navigator, go to Click Here . An account on Cisco.com is not required.

Prerequisites for GLBP

Before configuring GLBP, ensure that the devices can support multiple MAC addresses on the physical interfaces. For each GLBP forwarder to be configured, an additional MAC address is used.

Restrictions for GLBP

Enhanced Object Tracking (EOT) is not stateful switchover (SSO)-aware and cannot be used with GLBP in SSO mode.

Information About GLBP

- GLBP Overview

- GLBP Active Virtual Gateway

- GLBP Virtual MAC Address Assignment

- GLBP Virtual Gateway Redundancy

- GLBP Virtual Forwarder Redundancy

- GLBP Gateway Priority

- GLBP Gateway Weighting and Tracking

- GLBP Client Cache

- GLBP MD5 Authentication

- ISSU-GLBP

- GLBP SSO

- GLBP Benefits

GLBP Overview

GLBP provides automatic device backup for IP hosts configured with a single default gateway on an IEEE 802.3 LAN. Multiple first-hop devices on the LAN combine to offer a single virtual first-hop IP device while sharing the IP packet forwarding load. Other devices on the LAN act as redundant GLBP devices that will become active if any of the existing forwarding devices fail.

GLBP performs a similar function for the user as HSRP and VRRP. HSRP and VRRP allow multiple devices to participate in a virtual device group configured with a virtual IP address. One member is elected to be the active device to forward packets sent to the virtual IP address for the group. The other devices in the group are redundant until the active device fails. These standby devices have unused bandwidth that the protocol is not using. Although multiple virtual device groups can be configured for the same set of devices, the hosts must be configured for different default gateways, which results in an extra administrative burden. The advantage of GLBP is that it additionally provides load balancing over multiple devices (gateways) using a single virtual IP address and multiple virtual MAC addresses. The forwarding load is shared among all devices in a GLBP group rather than being handled by a single device while the other devices stand idle. Each host is configured with the same virtual IP address, and all devices in the virtual device group participate in forwarding packets. GLBP members communicate between each other through hello messages sent every 3 seconds to the multicast address 224.0.0.102, UDP port 3222 (source and destination).

GLBP Packet Types

GLBP uses 3 different packet types to operate. The packet types are Hello, Request, and Reply. The Hello packet is used to advertise protocol information. Hello packets are multicast, and are sent when any virtual gateway or virtual forwarder is in Speak, Standby or Active state. Request and Reply packets are used for virtual MAC assignment. They are both unicast messages to and from the active virtual gateway (AVG).

GLBP Active Virtual Gateway

Members of a GLBP group elect one gateway to be the active virtual gateway (AVG) for that group. Other group members provide backup for the AVG if the AVG becomes unavailable. The AVG assigns a virtual MAC address to each member of the GLBP group. Each gateway assumes responsibility for forwarding packets sent to the virtual MAC address assigned to it by the AVG. These gateways are known as active virtual forwarders (AVFs) for their virtual MAC address.

The AVG is also responsible for answering Address Resolution Protocol (ARP) requests for the virtual IP address. Load sharing is achieved by the AVG replying to the ARP requests with different virtual MAC addresses.

Prior to Cisco IOS Release 15.0(1)M1 and 12.4(24)T2, when the no glbp load-balancing command is configured, the AVG always responds to ARP requests with the MAC address of its AVF.

In Cisco IOS Release 15.0(1)M1 and 12.4(24)T2, and later releases, when the no glbp load-balancing command is configured, if the AVG does not have an AVF, it preferentially responds to ARP requests with the MAC address of the first listening virtual forwarder (VF), which will causes traffic to route via another gateway until that VF migrates back to being the current AVG.

In the figure below, Router A (or Device A) is the AVG for a GLBP group, and is responsible for the virtual IP address 10.21.8.10. Router A is also an AVF for the virtual MAC address 0007.b400.0101. Router B (or Device B) is a member of the same GLBP group and is designated as the AVF for the virtual MAC address 0007.b400.0102. Client 1 has a default gateway IP address of 10.21.8.10 and a gateway MAC address of 0007.b400.0101. Client 2 shares the same default gateway IP address but receives the gateway MAC address 0007.b400.0102 because Router B is sharing the traffic load with Router A.

GLBP Topology

If Router A becomes unavailable, Client 1 will not lose access to the WAN because Router B will assume responsibility for forwarding packets sent to the virtual MAC address of Router A, and for responding to packets sent to its own virtual MAC address. Router B will also assume the role of the AVG for the entire GLBP group. Communication for the GLBP members continues despite the failure of a device in the GLBP group.

GLBP Virtual MAC Address Assignment

A GLBP group allows up to four virtual MAC addresses per group. The AVG is responsible for assigning the virtual MAC addresses to each member of the group. Other group members request a virtual MAC address after they discover the AVG through hello messages. Gateways are assigned the next MAC address in sequence. A virtual forwarder that is assigned a virtual MAC address by the AVG is known as a primary virtual forwarder. Other members of the GLBP group learn the virtual MAC addresses from hello messages. A virtual forwarder that has learned the virtual MAC address is referred to as a secondary virtual forwarder.

GLBP Virtual Gateway Redundancy

GLBP operates virtual gateway redundancy in the same way as HSRP. One gateway is elected as the AVG, another gateway is elected as the standby virtual gateway, and the remaining gateways are placed in a listen state.

If an AVG fails, the standby virtual gateway will assume responsibility for the virtual IP address. A new standby virtual gateway is then elected from the gateways in the listen state.

GLBP Virtual Forwarder Redundancy

Virtual forwarder redundancy is similar to virtual gateway redundancy with an AVF. If the AVF fails, one of the secondary virtual forwarders in the listen state assumes responsibility for the virtual MAC address.

The new AVF is also a primary virtual forwarder for a different forwarder number. GLBP migrates hosts away from the old forwarder number using two timers that start as soon as the gateway changes to the active virtual forwarder state. GLBP uses the hello messages to communicate the current state of the timers.

The redirect time is the interval during which the AVG continues to redirect hosts to the old virtual forwarder MAC address. When the redirect time expires, the AVG stops using the old virtual forwarder MAC address in ARP replies, although the virtual forwarder will continue to forward packets that were sent to the old virtual forwarder MAC address.

The secondary holdtime is the interval during which the virtual forwarder is valid. When the secondary holdtime expires, the virtual forwarder is removed from all gateways in the GLBP group. The expired virtual forwarder number becomes eligible for reassignment by the AVG.

GLBP Gateway Priority

GLBP gateway priority determines the role that each GLBP gateway plays and what happens if the AVG fails.

Priority also determines if a GLBP device functions as a backup virtual gateway and the order of ascendancy to becoming an AVG if the current AVG fails. You can configure the priority of each backup virtual gateway with a value of 1 through 255 using the glbp priority command.

In the "GLBP Topology" figure, if Router A (or Device A)—the AVG in a LAN topology—fails, an election process takes place to determine which backup virtual gateway should take over. In this example, Router B (or Device B) is the only other member in the group so it will automatically become the new AVG. If another device existed in the same GLBP group with a higher priority, then the device with the higher priority would be elected. If both devices have the same priority, the backup virtual gateway with the higher IP address would be elected to become the active virtual gateway.

By default, the GLBP virtual gateway preemptive scheme is disabled. A backup virtual gateway can become the AVG only if the current AVG fails, regardless of the priorities assigned to the virtual gateways. You can enable the GLBP virtual gateway preemptive scheme using the glbp preempt command. Preemption allows a backup virtual gateway to become the AVG, if the backup virtual gateway is assigned a higher priority than the current AVG.

GLBP Gateway Weighting and Tracking

GLBP uses a weighting scheme to determine the forwarding capacity of each device in the GLBP group. The weighting assigned to a device in the GLBP group can be used to determine whether it will forward packets and, if so, the proportion of hosts in the LAN for which it will forward packets. Thresholds can be set to disable forwarding when the weighting for a GLBP group falls below a certain value, and when it rises above another threshold, forwarding is automatically reenabled.

The GLBP group weighting can be automatically adjusted by tracking the state of an interface within the device. If a tracked interface goes down, the GLBP group weighting is reduced by a specified value. Different interfaces can be tracked to decrement the GLBP weighting by varying amounts.

By default, the GLBP virtual forwarder preemptive scheme is enabled with a delay of 30 seconds. A backup virtual forwarder can become the AVF if the current AVF weighting falls below the low weighting threshold for 30 seconds. You can disable the GLBP forwarder preemptive scheme using the no glbp forwarder preempt command or change the delay using the glbp forwarder preempt delay minimum command.

GLBP Client Cache

The GLBP client cache contains information about network hosts that are using a GLBP group as the default gateway.

When an IPv4 Address Resolution Protocol (ARP) request or an IPv6 Neighbor Discovery (ND) request for a GLBP virtual IP address is received from a network host by a GLBP group’s active virtual gateway (AVG), a new entry is created in the GLBP client cache. The cache entry contains information about the host that sent the ARP or ND request and which forwarder the AVG has assigned to it.

The GLBP client cache stores the MAC address of each host that is using a particular GLBP group, the number of the GLBP forwarder that each network host has been assigned to and the total number of network hosts currently assigned to each forwarder in a GLBP group. The GLBP client cache also stores the protocol address used by each network host and the time elapsed since the host-to-forwarder assignment was last updated.

The GLBP client cache can store information on up to 2000 network hosts for a GLBP group. The expected normal maximum configuration is 1000 network hosts. You can configure a lower maximum number of network hosts that will be cached for each GLBP group independently based on the number of network hosts that are using each GLBP group by using the glbp client-cache maximum command. This command enables you to limit the amount of memory used by the cache per GLBP group. If the GLBP client cache has reached the maximum configured number of clients and a new client is added, the least recently updated client entry will be discarded. Reaching this condition indicates that the configured maximum limit is too small.

The amount of memory that is used by the GLBP client cache depends on the number of network hosts using GLBP groups for which the client cache is enabled. For each host at least 20 bytes is required, with an additional 3200 bytes per GLBP group.

You can display the contents of the GLBP client cache using the show glbp detail command on the device that is currently the AVG for a GLBP group. If you issue the show glbp detail command on any other device in a GLBP group, you will be directed to reissue the command on the AVG to view client cache information. The show glbp detail command also displays statistics about the GLBP client cache usage and the distribution of clients among forwarders. These statistics are accurate as long as the cache timeout and client limit parameters have been set appropriately. Appropriate values would be where the number of end hosts on the network does not exceed the configured limit and where the maximum end host ARP cache timeout does not exceed the configured GLBP client cache timeout.

You can enable or disable the GLBP client cache independently for each GLBP group by using the glbp client-cache command. The GLBP client cache is disabled by default. There is no limit on the number of groups for which the GLBP client cache can be enabled.

You can configure GLBP cache entries to time out after a specified time by using the timeout keyword option with the glbp client-cache maximum command.

GLBP MD5 Authentication

GLBP MD5 authentication uses the industry-standard MD5 algorithm for improved reliability and security. MD5 authentication provides greater security than the alternative plain text authentication scheme and protects against spoofing software.

MD5 authentication allows each GLBP group member to use a secret key to generate a keyed MD5 hash that is part of the outgoing packet. A keyed hash of an incoming packet is generated and, if the hash within the incoming packet does not match the generated hash, the packet is ignored.

The key for the MD5 hash can either be given directly in the configuration using a key string or supplied indirectly through a key chain. The key string cannot exceed 100 characters in length.

A device will ignore incoming GLBP packets from devices that do not have the same authentication configuration for a GLBP group. GLBP has three authentication schemes:

- No authentication

- Plain text authentication

- MD5 authentication

GLBP packets will be rejected in any of the following cases:

- The authentication schemes differ on the device and in the incoming packet.

- MD5 digests differ on the device and in the incoming packet.

- Text authentication strings differ on the device and in the incoming packet.

ISSU-GLBP

GLBP supports In Service Software Upgrade (ISSU). ISSU allows a high-availability (HA) system to run in Stateful Switchover (SSO) mode even when different versions of Cisco IOS software are running on the active and standby Route Processors (RPs) or line cards.

ISSU provides the ability to upgrade or downgrade from one supported Cisco IOS release to another while continuing to forward packets and maintain sessions, thereby reducing planned outage time. The ability to upgrade or downgrade is achieved by running different software versions on the active RP and standby RP for a short period of time to maintain state information between RPs. This feature allows the system to switch over to a secondary RP running upgraded (or downgraded) software and continue forwarding packets without session loss and with minimal or no packet loss. This feature is enabled by default.

For detailed information about ISSU, see the Cisco IOS In Service Software Upgrade Process in the Cisco IOS High Availability Configuration Guide

For detailed information about ISSU on the 7600 series devices, see the ISSU and eFSU on Cisco 7600 Series Routers document.

GLBP SSO

With the introduction of the GLBP SSO functionality, GLBP is stateful switchover (SSO) aware. GLBP can detect when a device is failing over to the secondary router processor (RP) and continue in its current group state.

SSO functions in networking devices (usually edge devices) that support dual RPs. SSO provides RP redundancy by establishing one of the RPs as the active processor and the other RP as the standby processor. SSO also synchronizes critical state information between the RPs so that network state information is dynamically maintained between RPs.

Without SSO-awareness, if GLBP is deployed on a device with redundant RPs, a switchover of roles between the active RP and the standby RP results in the device relinquishing its activity as a GLBP group member and then rejoining the group as if it had been reloaded. The GLBP SSO feature enables GLBP to continue its activities as a group member during a switchover. GLBP state information between redundant RPs is maintained so that the standby RP can continue the device’s activities within the GLBP during and after a switchover.

This feature is enabled by default. To disable this feature, use the no glbp sso command in global configuration mode.

For more information, see the Stateful Swithover document in the Cisco IOS High Availability Configuration Guide.

GLBP Benefits

Load Sharing

You can configure GLBP in such a way that traffic from LAN clients can be shared by multiple devices, thereby sharing the traffic load more equitably among available devices.

Multiple Virtual Devices

GLBP supports up to 1024 virtual devices (GLBP groups) on each physical interface of a device and up to four virtual forwarders per group.

Preemption

The redundancy scheme of GLBP enables you to preempt an active virtual gateway (AVG) with a higher priority backup virtual gateway that has become available. Forwarder preemption works in a similar way, except that forwarder preemption uses weighting instead of priority and is enabled by default.

Authentication

GLBP supports the industry-standard message digest 5 (MD5) algorithm for improved reliability, security, and protection against GLBP-spoofing software. A device within a GLBP group with a different authentication string than other devices will be ignored by other group members. You can alternatively use a simple text password authentication scheme between GLBP group members to detect configuration errors.

How to Configure GLBP

- Enabling and Verifying GLBP

- Customizing GLBP

- Configuring GLBP MD5 Authentication Using a Key String

- Configuring GLBP MD5 Authentication Using a Key Chain

- Configuring GLBP Text Authentication

- Configuring GLBP Weighting Values and Object Tracking

- Troubleshooting GLBP

Enabling and Verifying GLBP

Perform this task to enable GLBP on an interface and verify its configuration and operation. GLBP is designed to be easy to configure. Each gateway in a GLBP group must be configured with the same group number, and at least one gateway in the GLBP group must be configured with the virtual IP address to be used by the group. All other required parameters can be learned.

Before You Begin

If VLANs are in use on an interface, the GLBP group number must be different for each VLAN.

SUMMARY STEPS

1.    enable

2.    configure terminal

3.    interface type number

4.    ip address ip-address mask [secondary]

5.    glbp group ip [ip-address [secondary]]

6.    exit

7.    show glbp [interface-type interface-number] [group] [state] [brief]

DETAILED STEPS

Command or Action

Purpose

Step 1

enable

Example:

Device> enable

Enables privileged EXEC mode.

- Enter your password if prompted.

Step 2

configure terminal

Example:

Device# configure terminal

Enters global configuration mode.

Step 3

interface type number

Example:

Specifies an interface type and number, and enters interface configuration mode.

Step 4

ip address ip-address mask [secondary]

Example:

Device(config-if)# ip address 10.21.8.32 255.255.255.0

Specifies a primary or secondary IP address for an interface.

Step 5

glbp group ip [ip-address [secondary]]

Example:

Device(config-if)# glbp 10 ip 10.21.8.10

Enables GLBP on an interface and identifies the primary IP address of the virtual gateway.

- After you identify a primary IP address, you can use the glbp group ip command again with the secondary keyword to indicate additional IP addresses supported by this group.

Step 6

exit

Example:

Device(config-if)# exit

Exits interface configuration mode, and returns the device to global configuration mode.

Step 7

show glbp [interface-type interface-number] [group] [state] [brief]

Example:

Device(config)# show glbp 10

(Optional) Displays information about GLBP groups on a device.

- Use the optional brief keyword to display a single line of information about each virtual gateway or virtual forwarder.

Example

In the following example, sample output is displayed about the status of the GLBP group, named 10, on the device:

Device# show glbp 10

GigabitEthernet0/0/0 - Group 10
State is Active
2 state changes, last state change 23:50:33
Virtual IP address is 10.21.8.10
Hello time 5 sec, hold time 18 sec
Next hello sent in 4.300 secs
Redirect time 600 sec, forwarder time-out 7200 sec
Authentication text "stringabc"
Preemption enabled, min delay 60 sec
Active is local
Standby is unknown
Priority 254 (configured)
Weighting 105 (configured 110), thresholds: lower 95, upper 105
Track object 2 state Down decrement 5
Load balancing: host-dependent
There is 1 forwarder (1 active)
Forwarder 1
State is Active
1 state change, last state change 23:50:15
MAC address is 0007.b400.0101 (default)
Owner ID is 0005.0050.6c08
Redirection enabled
Preemption enabled, min delay 60 sec
Active is local, weighting 105

Customizing GLBP

Customizing the behavior of GLBP is optional. Be aware that as soon as you enable a GLBP group, that group is operating. It is possible that if you first enable a GLBP group before customizing GLBP, the device could take over control of the group and become the AVG before you have finished customizing the feature. Therefore, if you plan to customize GLBP, it is a good idea to do so before enabling GLBP.

SUMMARY STEPS

1.    enable

2.    configure terminal

3.    interface type number

4.    ip address ip-address mask [secondary]

5.    glbp group timers [msec] hellotime [msec] holdtime

6.    glbp group timers redirect redirect timeout

7.    glbp group load-balancing [host-dependent | round-robin | weighted]

8.    glbp group priority level

9.    glbp group preempt [delay minimum seconds]

10.    glbp group client-cache maximum number [timeout minutes]

11.    glbp group name redundancy-name

12.    exit

13.    no glbp sso

DETAILED STEPS

Command or Action

Purpose

Step 1

enable

Example:

Device> enable

Enables privileged EXEC mode.

- Enter your password if prompted.

Step 2

configure terminal

Example:

Device# configure terminal

Enters global configuration mode.

Step 3

interface type number

Example:

Device(config)# interface fastethernet 0/0

Specifies an interface type and number, and enters interface configuration mode.

Step 4

ip address ip-address mask [secondary]

Example:

Device(config-if)# ip address 10.21.8.32 255.255.255.0

Specifies a primary or secondary IP address for an interface.

Step 5

glbp group timers [msec] hellotime [msec] holdtime

Example:

Device(config-if)# glbp 10 timers 5 18

Configures the interval between successive hello packets sent by the AVG in a GLBP group.

- The holdtime argument specifies the interval in seconds before the virtual gateway and virtual forwarder information in the hello packet is considered invalid.

- The optional msec keyword specifies that the following argument will be expressed in milliseconds, instead of the default seconds.

Step 6

glbp group timers redirect redirect timeout

Example:

Device(config-if)# glbp 10 timers redirect 1800 28800

Configures the time interval during which the AVG continues to redirect clients to an AVF. The default is 600 seconds (10 minutes).

- The timeout argument specifies the interval in seconds before a secondary virtual forwarder becomes invalid. The default is 14,400 seconds (4 hours).

Note:
The zero value for the redirect argument cannot be removed from the range of acceptable values because preexisting configurations of Cisco IOS software already using the zero value could be negatively affected during an upgrade. However, a zero setting is not recommended and, if used, results in a redirect timer that never expires. If the redirect timer does not expire, and the device fails, new hosts continue to be assigned to the failed device instead of being redirected to the backup.

Step 7

glbp group load-balancing [host-dependent | round-robin | weighted]

Example:

Device(config-if)# glbp 10 load-balancing host-dependent

Specifies the method of load balancing used by the GLBP AVG.

Step 8

glbp group priority level

Example:

Device(config-if)# glbp 10 priority 254

Sets the priority level of the gateway within a GLBP group.

- The default value is 100.

Step 9

glbp group preempt [delay minimum seconds]

Example:

Device(config-if)# glbp 10 preempt delay minimum 60

Configures the device to take over as AVG for a GLBP group if it has a higher priority than the current AVG.

- This command is disabled by default.

- Use the optional delay and minimum keywords and the seconds argument to specify a minimum delay interval in seconds before preemption of the AVG takes place.

Step 10

glbp group client-cache maximum number [timeout minutes]

Example:

Device(config-if)# glbp 10 client-cache maximum 1200 timeout 245

(Optional) Enables the GLBP client cache.

- This command is disabled by default.

- Use the number argument to specify the maximum number of clients the cache will hold for this GLBP group. The range is from 8 to 2000.

- Use the optional timeout minutes keyword and argument pair to configure the maximum amount of time a client entry can stay in the GLBP client cache after the client information was last updated. The range is from 1 to 1440 minutes (one day).

Note:
For IPv4 networks, Cisco recommends setting a GLBP client cache timeout value that is slightly longer than the maximum expected end-host Address Resolution Protocol (ARP) cache timeout value.

Step 11

glbp group name redundancy-name

Example:

Device(config-if)# glbp 10 name abc123

Enables IP redundancy by assigning a name to the GLBP group.

- The GLBP redundancy client must be configured with the same GLBP group name so the redundancy client and the GLBP group can be connected.

Step 12

exit

Example:

Device(config-if)# exit

Exits interface configuration mode, and returns the device to global configuration mode.

Step 13

no glbp sso

Example:

Device(config)# no glbp sso

(Optional) Disables GLBP support of SSO.

Configuring GLBP MD5 Authentication Using a Key String

SUMMARY STEPS

1.    enable

2.    configure terminal

3.    interface type number

4.    ip address ip-address mask [secondary]

5.    glbp group-number authentication md5 key-string [ 0 | 7] key

6.    glbp group-number ip [ip-address [secondary]]

7.    Repeat Steps 1 through 6 on each device that will communicate.

8.    end

9.    show glbp

DETAILED STEPS

Command or Action

Purpose

Step 1

enable

Example:

Device> enable

Enables privileged EXEC mode.

- Enter your password if prompted.

Step 2

configure terminal

Example:

Device# configure terminal

Enters global configuration mode.

Step 3

interface type number

Example:

Device(config)# interface Ethernet0/1

Configures an interface type and enters interface configuration mode.

Step 4

ip address ip-address mask [secondary]

Example:

Device(config-if)# ip address 10.0.0.1 255.255.255.0

Specifies a primary or secondary IP address for an interface.

Step 5

glbp group-number authentication md5 key-string [ 0 | 7] key

Example:

Device(config-if)# glbp 1 authentication md5 key-string d00b4r987654321a

Configures an authentication key for GLBP MD5 authentication.

- The key string cannot exceed 100 characters in length.

- No prefix to the key argument or specifying 0 means the key is unencrypted.

- Specifying 7 means the key is encrypted. The key-string authentication key will automatically be encrypted if the service password-encryption global configuration command is enabled.

Step 6

glbp group-number ip [ip-address [secondary]]

Example:

Device(config-if)# glbp 1 ip 10.0.0.10

Enables GLBP on an interface and identifies the primary IP address of the virtual gateway.

Step 7

Repeat Steps 1 through 6 on each device that will communicate.

—

Step 8

end

Example:

Device(config-if)# end

Returns to privileged EXEC mode.

Step 9

show glbp

Example:

Device# show glbp

(Optional) Displays GLBP information.

- Use this command to verify your configuration. The key string and authentication type will be displayed if configured.

Configuring GLBP MD5 Authentication Using a Key Chain

Perform this task to configure GLBP MD5 authentication using a key chain. Key chains allow a different key string to be used at different times according to the key chain configuration. GLBP will query the appropriate key chain to obtain the current live key and key ID for the specified key chain.

SUMMARY STEPS

1.    enable

2.    configure terminal

3.    key chain name-of-chain

4.    key key-id

5.    key-string string

6.    exit

7.    exit

8.    interface type number

9.    ip address ip-address mask [secondary]

10.    glbp group-number authentication md5 key-chain name-of-chain

11.    glbp group-number ip [ip-address [secondary]]

12.    Repeat Steps 1 through 10 on each device that will communicate.

13.    end

14.    show glbp

15.    show key chain

DETAILED STEPS

Command or Action

Purpose

Step 1

enable

Example:

Device> enable

Enables privileged EXEC mode.

- Enter your password if prompted.

Step 2

configure terminal

Example:

Device# configure terminal

Enters global configuration mode.

Step 3

key chain name-of-chain

Example:

Device(config)# key chain glbp2

Enables authentication for routing protocols and identifies a group of authentication keys and enters key-chain configuration mode.

Step 4

key key-id

Example:

Device(config-keychain)# key 100

Identifies an authentication key on a key chain.

- The value for the key-id argument must be a number.

Step 5

key-string string

Example:

Device(config-keychain-key)# key-string abc123

Specifies the authentication string for a key and enters key-chain key configuration mode.

- The value for the string argument can be 1 to 80 uppercase or lowercase alphanumeric characters; the first character cannot be a numeral.

Step 6

exit

Example:

Device(config-keychain-key)# exit

Returns to key-chain configuration mode.

Step 7

exit

Example:

Device(config-keychain)# exit

Returns to global configuration mode.

Step 8

interface type number

Example:

Device(config)# interface Ethernet0/1

Configures an interface type and enters interface configuration mode.

Step 9

ip address ip-address mask [secondary]

Example:

Device(config-if)# ip address 10.21.0.1 255.255.255.0

Specifies a primary or secondary IP address for an interface.

Step 10

glbp group-number authentication md5 key-chain name-of-chain

Example:

Device(config-if)# glbp 1 authentication md5 key-chain glbp2

Configures an authentication MD5 key chain for GLBP MD5 authentication.

- The key chain name must match the name specified in Step 3.

Step 11

glbp group-number ip [ip-address [secondary]]

Example:

Device(config-if)# glbp 1 ip 10.21.0.12

Enables GLBP on an interface and identifies the primary IP address of the virtual gateway.

Step 12

Repeat Steps 1 through 10 on each device that will communicate.

—

Step 13

end

Example:

Device(config-if)# end

Returns to privileged EXEC mode.

Step 14

show glbp

Example:

Device# show glbp

(Optional) Displays GLBP information.

- Use this command to verify your configuration. The key chain and authentication type will be displayed if configured.

Step 15

show key chain

Example:

Device# show key chain

(Optional) Displays authentication key information.

Configuring GLBP Text Authentication

Text authentication provides minimal security. Use MD5 authentication if security is required.

SUMMARY STEPS

1.    enable

2.    configure terminal

3.    interface type number

4.    ip address ip-address mask [secondary]

5.    glbp group-number authentication text string

6.    glbp group-number ip [ip-address [secondary]]

7.    Repeat Steps 1 through 6 on each device that will communicate.

8.    end

9.    show glbp

DETAILED STEPS

Command or Action

Purpose

Step 1

enable

Example:

Device> enable

Enables privileged EXEC mode.

- Enter your password if prompted.

Step 2

configure terminal

Example:

Device# configure terminal

Enters global configuration mode.

Step 3

interface type number

Example:

Device(config)# interface Ethernet0/1

Configures an interface type and enters interface configuration mode.

Step 4

ip address ip-address mask [secondary]

Example:

Device(config-if)# ip address 10.0.0.1 255.255.255.0

Specifies a primary or secondary IP address for an interface.

Step 5

glbp group-number authentication text string

Example:

Device(config-if)# glbp 10 authentication text stringxyz

Authenticates GLBP packets received from other devices in the group.

- If you configure authentication, all devices within the GLBP group must use the same authentication string.

Step 6

glbp group-number ip [ip-address [secondary]]

Example:

Device(config-if)# glbp 1 ip 10.0.0.10

Enables GLBP on an interface and identifies the primary IP address of the virtual gateway.

Step 7

Repeat Steps 1 through 6 on each device that will communicate.

—

Step 8

end

Example:

Device(config-if)# end

Returns to privileged EXEC mode.

Step 9

show glbp

Example:

Device# show glbp

(Optional) Displays GLBP information.

- Use this command to verify your configuration.

Configuring GLBP Weighting Values and Object Tracking

GLBP weighting is used to determine whether a GLBP group can act as a virtual forwarder. Initial weighting values can be set and optional thresholds specified. Interface states can be tracked and a decrement value set to reduce the weighting value if the interface goes down. When the GLBP group weighting drops below a specified value, the group will no longer be an active virtual forwarder. When the weighting rises above a specified value, the group can resume its role as an active virtual forwarder.

SUMMARY STEPS

1.    enable

2.    configure terminal

3.    track object-number interface type number {line-protocol | ip routing}

4.    exit

5.    interface type number

6.    glbp group weighting maximum [lower lower] [upper upper]

7.    glbp group weighting track object-number [decrement value]

8.    glbp group forwarder preempt [delay minimum seconds]

9.    exit

10.    show track [object-number | brief] [interface [brief] | ip route [ brief] | resolution | timers]

DETAILED STEPS

Command or Action

Purpose

Step 1

enable

Example:

Device> enable

Enables privileged EXEC mode.

- Enter your password if prompted.

Step 2

configure terminal

Example:

Device# configure terminal

Enters global configuration mode.

Step 3

track object-number interface type number {line-protocol | ip routing}

Example:

Device(config)# track 2 interface POS 6/0/0 ip routing

Configures an interface to be tracked where changes in the state of the interface affect the weighting of a GLBP gateway, and enters tracking configuration mode.

- This command configures the interface and corresponding object number to be used with the glbp weighting track command.

- The line-protocol keyword tracks whether the interface is up. The ip routing keywords also check that IP routing is enabled on the interface, and an IP address is configured.

Step 4

exit

Example:

Device(config-track)# exit

Returns to global configuration mode.

Step 5

interface type number

Example:

Device(config)# interface GigabitEthernet 0/0/0

Enters interface configuration mode.

Step 6

glbp group weighting maximum [lower lower] [upper upper]

Example:

Device(config-if)# glbp 10 weighting 110 lower 95 upper 105

Specifies the initial weighting value, and the upper and lower thresholds, for a GLBP gateway.

Step 7

glbp group weighting track object-number [decrement value]

Example:

Device(config-if)# glbp 10 weighting track 2 decrement 5

Specifies an object to be tracked that affects the weighting of a GLBP gateway.

- The value argument specifies a reduction in the weighting of a GLBP gateway when a tracked object fails.

Step 8

glbp group forwarder preempt [delay minimum seconds]

Example:

Device(config-if)# glbp 10 forwarder preempt delay minimum 60

Configures the device to take over as AVF for a GLBP group if the current AVF for a GLBP group falls below its low weighting threshold.

- This command is enabled by default with a delay of 30 seconds.

- Use the optional delay and minimum keywords and the seconds argument to specify a minimum delay interval in seconds before preemption of the AVF takes place.

Step 9

exit

Example:

Device(config-if)# exit

Returns to privileged EXEC mode.

Step 10

show track [object-number | brief] [interface [brief] | ip route [ brief] | resolution | timers]

Example:

Device# show track 2

Displays tracking information.

Troubleshooting GLBP

GLBP introduces five privileged EXEC mode commands to enable display of diagnostic output concerning various events relating to the operation of GLBP. The debug condition glbp,debug glbp errors, debug glbp events, debug glbp packets, and debug glbp terse commands are intended only for troubleshooting purposes because the volume of output generated by the software can result in severe performance degradation on the device. Perform this task to minimize the impact of using the debug glbp commands.

This procedure will minimize the load on the device created by the debug condition glbpor debug glbp command because the console port is no longer generating character-by-character processor interrupts. If you cannot connect to a console directly, you can run this procedure via a terminal server. If you must break the Telnet connection, however, you may not be able to reconnect because the device may be unable to respond due to the processor load of generating the debugging output.

Before You Begin

This task requires a device running GLBP to be attached directly to a console.

SUMMARY STEPS

1.    enable

2.    configure terminal

3.    no logging console

4.    Use Telnet to access a device port and repeat Steps 1 and 2.

5.    end

6.    terminal monitor

7.    debug condition glbp interface-type interface-number group [forwarder]

8.    terminal no monitor

DETAILED STEPS

Command or Action

Purpose

Step 1

enable

Example:

Device> enable

Enables privileged EXEC mode.

- Enter your password if prompted.

Step 2

configure terminal

Example:

Device# configure terminal

Enters global configuration mode.

Step 3

no logging console

Example:

Device(config)# no logging console

Disables all logging to the console terminal.

- To reenable logging to the console, use thelogging console command in global configuration mode.

Step 4

Use Telnet to access a device port and repeat Steps 1 and 2.

Enters global configuration mode in a recursive Telnet session, which allows the output to be redirected away from the console port.

Step 5

end

Example:

Device(config)# end

Exits to privileged EXEC mode.

Step 6

terminal monitor

Example:

Device# terminal monitor

Enables logging output on the virtual terminal.

Step 7

debug condition glbp interface-type interface-number group [forwarder]

Example:

Device# debug condition glbp GigabitEthernet0/0/0 1

Displays debugging messages about GLBP conditions.

- Try to enter only specific debug condition glbp or debug glbp commands to isolate the output to a certain subcomponent and minimize the load on the processor. Use appropriate arguments and keywords to generate more detailed debug information on specified subcomponents.

- Enter the specific no debug condition glbp or no debug glbp command when you are finished.

Step 8

terminal no monitor

Example:

Device# terminal no monitor

Disables logging on the virtual terminal.

Configuration Examples for GLBP

- Example: Customizing GLBP Configuration

- Example: Configuring GLBP MD5 Authentication Using Key Strings

- Example: Configuring GLBP MD5 Authentication Using Key Chains

- Example: Configuring GLBP Text Authentication

- Example: Configuring GLBP Weighting

- Example: Enabling GLBP Configuration

Example: Customizing GLBP Configuration

Device(config)# interface fastethernet 0/0
Device(config-if)# ip address 10.21.8.32 255.255.255.0
Device(config-if)# glbp 10 timers 5 18
Device(config-if)# glbp 10 timers redirect 1800 28800
Device(config-if)# glbp 10 load-balancing host-dependent
Device(config-if)# glbp 10 priority 254
Device(config-if)# glbp 10 preempt delay minimum 60

Device(config-if)# glbp 10 client-cache maximum 1200 timeout 245

Example: Configuring GLBP MD5 Authentication Using Key Strings

The following example shows how to configure GLBP MD5 authentication using a key string:

Device(config)# interface Ethernet 0/1
Device(config-if)# ip address 10.0.0.1 255.255.255.0
Device(config-if)# glbp 2 authentication md5 key-string ThisStringIsTheSecretKey
Device(config-if)# glbp 2 ip 10.0.0.10

Example: Configuring GLBP MD5 Authentication Using Key Chains

In the following example, GLBP queries the key chain “AuthenticateGLBP” to obtain the current live key and key ID for the specified key chain:

Device(config)# key chain AuthenticateGLBP
Device(config-keychain)# key 1
Device(config-keychain-key)# key-string ThisIsASecretKey
Device(config-keychain-key)# exit
Device(config-keychain)# exit
Device(config)# interface Ethernet 0/1
Device(config-if)# ip address 10.0.0.1 255.255.255.0
Device(config-if)# glbp 2 authentication md5 key-chain AuthenticateGLBP
Device(config-if)# glbp 2 ip 10.0.0.10

Example: Configuring GLBP Text Authentication

Device(config)# interface GigabitEthernet 0/0/0
Device(config-if)# ip address 10.21.8.32 255.255.255.0
Device(config-if)# glbp 10 authentication text stringxyz
Device(config-if)# glbp 10 ip 10.21.8.10

Example: Configuring GLBP Weighting

In the following example, the device is configured to track the IP routing state of the POS interface 5/0/0 and 6/0/0, an initial GLBP weighting with upper and lower thresholds is set, and a weighting decrement value of 10 is set. If POS interface 5/0/0 and 6/0/0 go down, the weighting value of the device is reduced.

Device(config)# track 1 interface POS 5/0/0 ip routing
Device(config)# track 2 interface POS 6/0/0 ip routing
Device(config)# interface fastethernet 0/0/0
Device(config-if)# glbp 10 weighting 110 lower 95 upper 105
Device(config-if)# glbp 10 weighting track 1 decrement 10
Device(config-if)# glbp 10 weighting track 2 decrement 10
Device(config-if)# glbp 10 forwarder preempt delay minimum 60

Example: Enabling GLBP Configuration

In the following example, the device is configured to enable GLBP, and the virtual IP address of 10.21.8.10 is specified for GLBP group 10:

Device(config)# interface GigabitEthernet 0/0/0
Device(config-if)# ip address 10.21.8.32 255.255.255.0
Device(config-if)# glbp 10 ip 10.21.8.10

Additional References for GLBP

Related Documents

Related Topic

Document Title

GLBP commands: complete command syntax, command mode, command history, defaults, usage guidelines, and examples

Cisco IOS IP Application Services Command Reference

In Service Software Upgrade (ISSU) configuration

"In Service Software Upgrade" process module in the Cisco IOS High Availability Configuration Guide

Key chains and key management commands: complete command syntax, command mode, command history, defaults, usage guidelines, and examples

Cisco IOS IP Routing Protocol-Independent Command Reference

Object tracking

"Configuring Enhanced Object Tracking" module

Stateful Switchover

The "Stateful Switchover" module in the Cisco IOS High Availability Configuration Guide

VRRP

"Configuring VRRP" module

HSRP

"Configuring HSRP" module

GLBP Support for IPv6

“FHRP - GLBP Support for IPv6” module

Technical Assistance

Description

Link

The Cisco Support and Documentation website provides online resources to download documentation, software, and tools. Use these resources to install and configure the software and to troubleshoot and resolve technical issues with Cisco products and technologies. Access to most tools on the Cisco Support and Documentation website requires a Cisco.com user ID and password.

Click Here

Feature Information for GLBP

The following table provides release information about the feature or features described in this module. This table lists only the software release that introduced support for a given feature in a given software release train. Unless noted otherwise, subsequent releases of that software release train also support that feature.

Use Cisco Feature Navigator to find information about platform support and Cisco software image support. To access Cisco Feature Navigator, go to Click Here . An account on Cisco.com is not required.

Feature Information for GLBP

Feature Name

Releases

Feature Configuration Information

Gateway Load Balancing Protocol

Cisco IOS XE 3.1.0SG 12.2(14)S 12.2(15)T 15.0(1)S

Cisco IOS XE Release 3.9S

GLBP protects data traffic from a failed device or circuit, like HSRP and VRRP, while allowing packet load sharing between a group of redundant devices.

The following commands were introduced or modified by this feature: glbp forwarder preempt, glbp ip, glbp load-balancing, glbp name, glbp preempt, glbp priority, glbp sso, glbp timers, glbp timers redirect, glbp weighting, glbp weighting track, show glbp.

GLBP Client Cache

12.4(15)T 12.2(33)SXI

The GLBP client cache contains information about network hosts that are using a GLBP group as the default gateway.

The GLBP client cache stores the MAC address of each host that is using a particular GLBP group, the number of the GLBP forwarder that each network host has been assigned to and the total number of network hosts currently assigned to each forwarder in a GLBP group. The GLBP client cache also stores the protocol address used by each network host and the time elapsed since the host-to-forwarder assignment was last updated.

The following commands were introduced or modified by this feature: glbp client-cache maximumand show glbp.

GLBP MD5 Authentication

Cisco IOS XE 3.1.0SG 12.2(18)S 12.3(2)T 12.2(33)SXH

MD5 authentication provides greater security than the alternative plain text authentication scheme. MD5 authentication allows each GLBP group member to use a secret key to generate a keyed MD5 hash that is part of the outgoing packet. A keyed hash of an incoming packet is generated and, if the hash within the incoming packet does not match the generated hash, the packet is ignored.

The following commands were modified by this feature: glbp authentication, show glbp.

ISSU--GLBP

12.2(31)SB2 12.2(33)SRB1

GLBP supports In Service Software Upgrade (ISSU). ISSU allows a high-availability (HA) system to run in Stateful Switchover (SSO) mode even when different versions of Cisco IOS software are running on the active and standby Route Processors (RPs) or line cards.

This feature provides customers with the same level of HA functionality for planned outages due to software upgrades as is available with SSO for unplanned outages. That is, the system can switch over to a secondary RP and continue forwarding packets without session loss and with minimal or no packet loss.

This feature is enabled by default.

There are no new or modified commands for this feature.

SSO--GLBP

12.2(31)SB2 12.2(33)SRB 12.2(33)SXH 15.0(1)S

GLBP is now SSO aware. GLBP can detect when a device is failing over to the secondary RP and continue in its current GLBP group state.

Prior to being SSO aware, GLBP was not able to detect that a second RP was installed and configured to take over in the event that the primary RP failed. When the primary failed, the GLBP device would stop participating in the GLBP group and, depending on its role, could trigger another device in the group to take over as the active device. With this enhancement, GLBP detects the failover to the secondary RP and no change occurs to the GLBP group. If the secondary RP fails and the primary is still not available, then the GLBP group detects this and re-elects a new active GLBP device.

This feature is enabled by default.

The following commands were introduced or modified by this feature: debug glbp events,glbp sso, show glbp.

Glossary

active RP—The Route Processor (RP) controls the system, provides network services, runs routing protocols and presents the system management interface.

AVF—active virtual forwarder. One virtual forwarder within a GLBP group is elected as active virtual forwarder for a specified virtual MAC address, and it is responsible for forwarding packets sent to that MAC address. Multiple active virtual forwarders can exist for each GLBP group.

AVG—active virtual gateway. One virtual gateway within a GLBP group is elected as the active virtual gateway, and is responsible for the operation of the protocol.

GLBP gateway—Gateway Load Balancing Protocol gateway. A router or gateway running GLBP. Each GLBP gateway may participate in one or more GLBP groups.

GLBP group—Gateway Load Balancing Protocol group. One or more GLBP gateways configured with the same GLBP group number on connected Ethernet interfaces.

ISSU—In Service Software Upgrade. A process that allows Cisco IOS XE software to be updated or otherwise modified while packet forwarding continues. In most networks, planned software upgrades are a significant cause of downtime. ISSU allows Cisco IOS software to be modified while packet forwarding continues, which increases network availability and reduces downtime caused by planned software upgrades.

NSF—nonstop forwarding. The ability of a router to continue to forward traffic to a router that may be recovering from a failure. Also, the ability of a router recovering from a failure to continue to correctly forward traffic sent to it by a peer.

RP—Route Processor. A generic term for the centralized control unit in a chassis. Platforms usually use a platform-specific term, such as RSP on the Cisco 7500, the PRE on the Cisco 10000, or the SUP+MSFC on the Cisco 7600.

RPR—Route Processor Redundancy. RPR provides an alternative to the High System Availability (HSA) feature. HSA enables a system to reset and use a standby Route Processor (RP) if the active RP fails. Using RPR, you can reduce unplanned downtime because RPR enables a quicker switchover between an active and standby RP if the active RP experiences a fatal error.

RPR+—An enhancement to RPR in which the standby RP is fully initialized.

SSO—Stateful Switchover. Enables applications and features to maintain state information between an active and standby unit.

standby RP—An RP that has been fully initialized and is ready to assume control from the active RP should a manual or fault-induced switchover occur.

switchover—An event in which system control and routing protocol execution are transferred from the active RP to the standby RP. Switchover may be a manual operation or may be induced by a hardware or software fault. Switchover may include transfer of the packet forwarding function in systems that combine system control and packet forwarding in an indivisible unit.

vIP—virtual IP address. An IPv4 address. There must be only one virtual IP address for each configured GLBP group. The virtual IP address must be configured on at least one GLBP group member. Other GLBP group members can learn the virtual IP address from hello messages.

Chapter 2. HSRP Version 2

- Finding Feature Information

- Information About HSRP Version 2

- How to Configure HSRP Version 2

- Configuration Examples for HSRP Version 2

- Additional References

- Feature Information for HSRP Version 2

Finding Feature Information

Your software release may not support all the features documented in this module. For the latest caveats and feature information, see Bug Search Tool and the release notes for your platform and software release. To find information about the features documented in this module, and to see a list of the releases in which each feature is supported, see the feature information table.

Use Cisco Feature Navigator to find information about platform support and Cisco software image support. To access Cisco Feature Navigator, go to Click Here . An account on Cisco.com is not required.

Information About HSRP Version 2

- HSRP Version 2 Design

HSRP Version 2 Design

HSRP version 2 is designed to address the following restrictions in HSRP version 1:

- In HSRP version 1, millisecond timer values are not advertised or learned. HSRP version 2 advertises and learns millisecond timer values. This change ensures stability of the HSRP groups in all cases.

- In HSRP version 1, group numbers are restricted to the range from 0 to 255. HSRP version 2 expands the group number range from 0 to 4095.

- HSRP version 2 provides improved management and troubleshooting. With HSRP version 1, you cannot use HSRP active hello messages to identify which physical device sent the message because the source MAC address is the HSRP virtual MAC address. The HSRP version 2 packet format includes a 6-byte identifier field that is used to uniquely identify the sender of the message. Typically, this field is populated with the interface MAC address.

- The multicast address 224.0.0.2 is used to send HSRP hello messages. This address can conflict with Cisco Group Management Protocol (CGMP) leave processing.

Version 1 is the default version of HSRP.

HSRP version 2 uses the new IP multicast address 224.0.0.102 to send hello packets instead of the multicast address of 224.0.0.2, used by HSRP version 1. This new multicast address allows CGMP leave processing to be enabled at the same time as HSRP.

HSRP version 2 permits an expanded group number range, 0 to 4095, and consequently uses a new MAC address range 0000.0C9F.F000 to 0000.0C9F.FFFF. The increased group number range does not imply that an interface can, or should, support that many HSRP groups. The expanded group number range was changed to allow the group number to match the VLAN number on subinterfaces.

When the HSRP version is changed, each group will reinitialize because it now has a new virtual MAC address.

HSRP version 2 has a different packet format than HSRP version 1. The packet format uses a type-length-value (TLV) format. HSRP version 2 packets received by an HSRP version 1 device will have the type field mapped to the version field by HSRP version 1 and subsequently ignored.

The Gateway Load Balancing Protocol (GLBP) also addresses the same restrictions relative to HSRP version 1 that HSRP version 2 does. See the Configuring GLBP document for more information on GLBP.

Jitter timers

Jitter timers are used in HSRP. They are recommended for timers running on services that work realtime and scale. Jitter timers are intended to significantly improve the reliability of HSRP, and other FHRP protocols, by reducing the chance of bunching of HSRP groups operations, and thus help reduce CPU and network traffic spikes. In the case of HSRP, a given device may have up to 4000 operational groups configured. In order to distribute the load on the device and network, the HSRP timers use a jitter. A given timer instance may take up to 20% more than the configured value. For example, for a hold time set to 15 seconds, the actual hold time may take 18 seconds.

In HSRP, the Hello timer (which sends the Hello Packet) has a negative Jitter, while the Holddown timer (which checks for failure of a peer) has a positive jitter.

How to Configure HSRP Version 2

- Changing to HSRP Version 2

Changing to HSRP Version 2

HSRP version 2 was introduced to prepare for further enhancements and to expand the capabilities beyond what is possible with HSRP version 1. HSRP version 2 has a different packet format than HSRP version 1.

Note

- HSRP version 2 is not available for ATM interfaces running LAN emulation.

- HSRP version 2 will not interoperate with HSRP version 1. An interface cannot operate both version 1 and version 2 because both versions are mutually exclusive. However, the different versions can be run on different physical interfaces of the same device. You cannot change from version 2 to version 1 if you have configured groups above the group number range allowed for version 1 (0 to 255).

SUMMARY STEPS

1.    enable

2.    configure terminal

3.    interface type number

4.    ip address ip-address mask

5.    standby version {1 | 2}

6.    standby [group-number] ip [ip-address [secondary]]

7.    end

8.    show standby

DETAILED STEPS

Command or Action

Purpose

Step 1

enable

Example:

Device> enable

Enables privileged EXEC mode.

- Enter your password if prompted.

Step 2

configure terminal

Example:

Device# configure terminal

Enters global configuration mode.

Step 3

interface type number

Example:

Device(config)# interface vlan 400

Configures an interface type and enters interface configuration mode.

Step 4

ip address ip-address mask

Example:

Device(config-if)# ip address 10.10.28.1 255.255.255.0

Sets an IP address for an interface.

Step 5

standby version {1 | 2}

Example:

Device(config-if)# standby version 2

Changes the HSRP version.

Step 6

standby [group-number] ip [ip-address [secondary]]

Example:

Device(config-if)# standby 400 ip 10.10.28.5

Activates HSRP.

- The group number range for HSRP version 2 is 0 through 4095. The group number range for HSRP version 1 is 0 through 255.

Step 7

end

Example:

Device(config-if)# end

Ends the current configuration session and returns to privileged EXEC mode.

Step 8

show standby

Example:

Device# show standby

(Optional) Displays HSRP information.

- HSRP version 2 information will be displayed if configured.

Configuration Examples for HSRP Version 2

- Example: Configuring HSRP Version 2

Example: Configuring HSRP Version 2

The following example shows how to configure HSRP version 2 on an interface with a group number of 350:

Device(config)# interface vlan 350
Device(config-if)# standby version 2
Device(config-if)# standby 350 priority 110
Device(config-if)# standby 350 preempt
Device(config-if)# standby 350 timers 5 15
Device(config-if)# standby 350 ip 172.20.100.10

Additional References

Related Documents

Related Topic

Document Title

Cisco IOS commands

Cisco IOS Master Commands List, All Releases

HSRP commands: complete command syntax, command mode, command history, defaults, usage guidelines, and examples

Cisco IOS First Hop redundancy Protocols Command Reference

HSRP for IPv6

“HSRP for IPv6” module

Troubleshooting HSRP

Hot Standby Router Protocol: Frequently Asked Questions

Standards

Standards

Title

No new or modified standards are supported by this feature, and support for existing standards has not been modified by this feature.

--

MIBs

MIBs

MIBs Link

CISCO-HSRP-MIB CISCO-HSRP-EXT-MIB

To locate and download MIBs for selected platforms, Cisco software releases, and feature sets, use Cisco MIB Locator found at the following URL:

Click Here

RFCs

RFCs

Title

RFC 792

Internet Control Message Protocol

RFC 1828

IP Authentication Using Keyed MD5

RFC 2281

Cisco Hot Standby Router Protocol

Technical Assistance

Description

Link

The Cisco Support and Documentation website provides online resources to download documentation, software, and tools. Use these resources to install and configure the software and to troubleshoot and resolve technical issues with Cisco products and technologies. Access to most tools on the Cisco Support and Documentation website requires a Cisco.com user ID and password.

Click Here

Feature Information for HSRP Version 2

The following table provides release information about the feature or features described in this module. This table lists only the software release that introduced support for a given feature in a given software release train. Unless noted otherwise, subsequent releases of that software release train also support that feature.

Use Cisco Feature Navigator to find information about platform support and Cisco software image support. To access Cisco Feature Navigator, go to Click Here . An account on Cisco.com is not required.

Feature Information for HSRP Version 2

Feature Name

Releases

Feature Information

HSRP Version 2

12.3(4)T

HSRP Version 2 feature was introduced to prepare for further enhancements and to expand the capabilities beyond what is possible with HSRP version 1. HSRP version 2 has a different packet format than HSRP version 1.

The following commands were introduced or modified by this feature: show standby, standby ip, standby version.

Chapter 3. FHRP—HSRP BFD Peering

The FHRP—HSRP BFD Peering feature introduces Bidirectional Forwarding Detection (BFD) in the Hot Standby Router Protocol (HSRP) group member health monitoring system. Before the introduction of this feature, group member monitoring relied exclusively on HSRP multicast messages, which are relatively large and consume CPU memory. In architectures where a single interface hosts a large number of groups, there is a need for a protocol with low CPU memory consumption and processing overhead. BFD addresses this issue and offers second health monitoring (failure detection in milliseconds) at a relatively low CPU impact.

IPv6 and IPv4 HSRP groups support BFD. If BFD is configured on an interface, all IPv4 and IPv6 HSRP groups will automatically support BFD.

- Finding Feature Information

- Restrictions for FHRP—HSRP BFD Peering

- Information About FHRP—HSRP BFD Peering

- How to Configure FHRP—HSRP BFD Peering

- Configuration Examples for FHRP—HSRP BFD Peering

- Additional References for FHRP—HSRP BFD Peering

- Feature Information for FHRP—HSRP BFD Peering

Finding Feature Information

Your software release may not support all the features documented in this module. For the latest caveats and feature information, see Bug Search Tool and the release notes for your platform and software release. To find information about the features documented in this module, and to see a list of the releases in which each feature is supported, see the feature information table.

Use Cisco Feature Navigator to find information about platform support and Cisco software image support. To access Cisco Feature Navigator, go to Click Here . An account on Cisco.com is not required.

Restrictions for FHRP—HSRP BFD Peering

Hot Standby Router Protocol (HSRP) support for Bidirectional Forwarding Detection (BFD) is not available for all platforms and interfaces.

Information About FHRP—HSRP BFD Peering

- HSRP BFD Peering

HSRP BFD Peering

The HSRP BFD Peering feature introduces Bidirectional Forwarding Detection (BFD) in the Hot Standby Router Protocol (HSRP) group member health monitoring system. HSRP supports BFD as a part of the HSRP group member health monitoring system. Without BFD, HSRP runs as a process in a multiprocess system and cannot be guaranteed to be scheduled in time to service large numbers of groups with hello and hold timers, in milliseconds. BFD runs as a pseudopreemptive process and can therefore be guaranteed to run when required. Only one BFD session between two devices can provide early failover notification for multiple HSRP groups.

This feature is enabled by default. The HSRP standby device learns the real IP address of the HSRP active device from the HSRP hello messages. The standby device registers as a BFD client and asks to be notified if the active device becomes unavailable. When BFD determines that the connections between standby and active devices has failed, it will notify HSRP on the standby device which will immediately take over as the active device.

BFD provides a low-overhead, short-duration method of detecting failures in the forwarding path between two adjacent devices, including the interfaces, data links, and forwarding planes. BFD is a detection protocol that you enable at the interface and routing protocol levels. Cisco supports the BFD asynchronous mode, which depends on the sending of BFD control packets between two systems to activate and maintain BFD neighbor sessions between devices. Therefore, to create a BFD session, you must configure BFD on both systems (or BFD peers). When BFD is enabled on the interfaces and at the device level for HSRP, a BFD session is created, BFD timers are negotiated, and the BFD peers will begin to send BFD control packets to each other at the negotiated interval.

BFD provides fast BFD peer failure detection times independently of all media types, encapsulations, topologies, and routing protocols such as, Border Gateway Protocol (BGP), Enhanced Interior Gateway Routing Protocol (EIGRP), Hot Standby Router Protocol (HSRP), Intermediate System To Intermediate System (IS-IS), and Open Shortest Path First (OSPF). By sending rapid failure detection notices to the routing protocols in the local device to initiate the routing table recalculation process, BFD contributes to greatly reduce overall network convergence time. The figure below shows a simple network with two devices running HSRP and BFD.

HSRP BFD Peering

For more information about BFD, see the IP Routing: BFD Configuration Guide.

How to Configure FHRP—HSRP BFD Peering

- Configuring BFD Session Parameters on an Interface

- Configuring HSRP BFD Peering

- Verifying HSRP BFD Peering

Configuring BFD Session Parameters on an Interface

Perform this task to configure Bidirectional Forwarding Detection (BFD) on an interface by setting the baseline BFD session parameters on the interface. Repeat the steps in this task for each interface on which you want to run BFD sessions to BFD neighbors.

SUMMARY STEPS

1.    enable

2.    configure terminal

3.    interface type number

4.    bfd interval milliseconds min_rx milliseconds multiplier interval-multiplier

5.    end

DETAILED STEPS

Command or Action

Purpose

Step 1

enable

Example:

Device> enable

Enables privileged EXEC mode.

- Enter your password if prompted.

Step 2

configure terminal

Example:

Device# configure terminal

Enters global configuration mode.

Step 3

interface type number

Example:

Device(config)# interface FastEthernet 6/0

Enters interface configuration mode.

Step 4

bfd interval milliseconds min_rx milliseconds multiplier interval-multiplier

Example:

Device(config-if)# bfd interval 50 min_rx 50 multiplier 5

Enables BFD on the interface.

Step 5

end

Example:

Device(config-if)# end

Exits interface configuration mode.

Configuring HSRP BFD Peering

Perform this task to enable Hot Standby Router Protocol (HSRP) Bidirectional Forwarding Detection (BFD) peering. Repeat the steps in this task for each interface over which you want to run BFD sessions to HSRP peers.

HSRP supports BFD peering by default. If HSRP BFD peering is disabled, you can reenable it at the device level to enable BFD support globally for all interfaces or you can reenable it on a per-interface basis at the interface level.

Before You Begin

Before you proceed with this task:

- HSRP must be running on all participating devices.

- Cisco Express Forwarding must be enabled.

SUMMARY STEPS

1.    enable

2.    configure terminal

3.    ip cef [distributed]

4.    interface type number

5.    ip address ip-address mask

6.    standby [group-number] ip [ip-address [secondary]]

7.    standby bfd

8.    exit

9.    standby bfd all-interfaces

10.    exit

11.    show standby [neighbors]

DETAILED STEPS

Command or Action

Purpose

Step 1

enable

Example:

Device> enable

Enables privileged EXEC mode.

- Enter your password if prompted.

Step 2

configure terminal

Example:

Device# configure terminal

Enters global configuration mode.

Step 3

ip cef [distributed]

Example:

Device(config)# ip cef

Enables Cisco Express Forwarding or distributed Cisco Express Forwarding.

Step 4

interface type number

Example:

Device(config)# interface FastEthernet 6/0

Enters interface configuration mode.

Step 5

ip address ip-address mask

Example:

Device(config-if)# ip address 10.0.0.11 255.255.255.0

Configures an IP address for the interface.

Step 6

standby [group-number] ip [ip-address [secondary]]

Example:

Device(config-if)# standby 1 ip 10.0.0.11

Activates HSRP.

Step 7

standby bfd

Example:

Device(config-if)# standby bfd

(Optional) Enables HSRP support for BFD on the interface.

Step 8

exit

Example:

Device(config-if)# exit

Exits interface configuration mode.

Step 9

standby bfd all-interfaces

Example:

Device(config)# standby bfd all-interfaces

(Optional) Enables HSRP support for BFD on all interfaces.

Step 10

exit

Example:

Device(config)# exit

Exits global configuration mode.

Step 11

show standby [neighbors]

Example:

Device# show standby neighbors

(Optional) Displays information about HSRP support for BFD.

Verifying HSRP BFD Peering

To verify Hot Standby Router Protocol (HSRP) Bidirectional Forwarding Detection (BFD) peering, use any of the following optional commands.

SUMMARY STEPS

1.    show standby

2.    show standby brief

3.    show standby neighbors [type number]

4.    show bfd neighbors

5.    show bfd neighbors details

DETAILED STEPS

Step 1

show standby

Use the show standby command to display HSRP information.

Example:

Device# show standby

FastEthernet2/0 - Group 1
State is Active
2 state changes, last state change 00:08:06
Virtual IP address is 10.0.0.11
Active virtual MAC address is 0000.0c07.ac01
Local virtual MAC address is 0000.0c07.ac01 (v1 default)
Hello time 3 sec, hold time 10 sec
Next hello sent in 2.772 secs
Preemption enabled
Active router is local
Standby router is 10.0.0.2, priority 90 (expires in 8.268 sec)
BFD enabled !
Priority 110 (configured 110)
Group name is "hsrp-Fa2/0-1" (default)

Step 2

show standby brief

Use the show standby brief command to display HSRP standby device information in brief.

Example:

Device# show standby brief

Interface   Grp  Pri P State   Active  Standby                     Virtual IP

Et0/0       4    120 P Active  local   172.24.1.2                  172.24.1.254
Et1/0       6    120 P Active  local   FE80::A8BB:CCFF:FE00:3401   FE80::5:73FF:FEA0:6

Step 3

show standby neighbors [type number]

Use the show standby neighbors command to display information about HSRP peer devices on an interface.

Example:

Device1# show standby neighbors

HSRP neighbors on FastEthernet2/0
10.1.0.22
No active groups
Standby groups: 1
BFD enabled !

Device2# show standby neighbors

HSRP neighbors on FastEthernet2/0
10.0.0.2
Active groups: 1
No standby groups
BFD enabled !

Step 4

show bfd neighbors

Use the show bfd neighbors command to display a line-by-line listing of existing Bidirectional Forwarding Detection (BFD) adjacencies.

Example:

Device# show bfd neighbors

IPv6 Sessions

NeighAddr                              LD/RD         RH/RS     State     Int

FE80::A8BB:CCFF:FE00:3401               4/3          Up        Up        Et1/0
FE80::A8BB:CCFF:FE00:3401               4/3          Up        Up        Et1/0

Step 5

show bfd neighbors details

Use the details keyword to display BFD protocol parameters and timers for each neighbor.

Example:

Device# show bfd neighbors details

OurAddr       NeighAddr     LD/RD  RH/RS   Holdown(mult)  State     Int
10.0.0.2      10.0.0.1       5/0    Down      0    (0 )   Down      Fa2/0
Local Diag: 0, Demand mode: 0, Poll bit: 0
MinTxInt: 1000000, MinRxInt: 1000000, Multiplier: 3
Received MinRxInt: 0, Received Multiplier: 0
Holdown (hits): 0(0), Hello (hits): 1000(55)
Rx Count: 0, Rx Interval (ms) min/max/avg: 0/0/0 last: 3314120 ms ago
Tx Count: 55, Tx Interval (ms) min/max/avg: 760/1000/872 last: 412 ms ago
Registered protocols: HSRP !
Last packet: Version: 1            - Diagnostic: 0
State bit: AdminDown  - Demand bit: 0
Poll bit: 0           - Final bit: 0
Multiplier: 0         - Length: 0
My Discr.: 0          - Your Discr.: 0
Min tx interval: 0    - Min rx interval: 0
Min Echo interval: 0

Configuration Examples for FHRP—HSRP BFD Peering

- Example: HSRP BFD Peering

Example: HSRP BFD Peering

Hot Standby Router Protocol (HSRP) supports Bidirectional Forwarding Detection (BFD) as a part of the HSRP group member health monitoring system. Without BFD, HSRP runs as a process in a multiprocess system and cannot be guaranteed to be scheduled in time to service large numbers of groups with millisecond hello and hold timers. BFD runs as a pseudo-preemptive process and can therefore, be guaranteed to run when required. Only one BFD session between two devices can provide early failover notification for multiple HSRP groups.

In the following example, the standby bfd and the standby bfd all-interfaces commands are not displayed. HSRP support for BFD is enabled by default when BFD is configured on a device or an interface by using the bfd interval command. The standby bfd and standby bfd all-interfaces commands are needed only if BFD has been manually disabled on a device or an interface.

Device A

DeviceA(config)# ip cef
DeviceA(config)# interface FastEthernet2/0
DeviceA(config-if)#  no shutdown
DeviceA(config-if)# ip address 10.0.0.2 255.0.0.0
DeviceA(config-if)# ip router-cache cef
DeviceA(config-if)# bfd interval 200 min_rx 200 multiplier 3
DeviceA(config-if)# standby 1 ip 10.0.0.11
DeviceA(config-if)# standby 1 preempt
DeviceA(config-if)# standby 1 priority 110
DeviceA(config-if)# standby 2 ip 10.0.0.12
DeviceA(config-if)# standby 2 preempt
DeviceA(config-if)# standby 2 priority 110

Device B

DeviceB(config)# interface FastEthernet2/0
DeviceB(config-if)# ip address 10.1.0.22 255.255.0.0
DeviceB(config-if)# no shutdown
DeviceB(config-if)# bfd interval 200 min_rx 200 multiplier 3
DeviceB(config-if)# standby 1 ip 10.0.0.11
DeviceB(config-if)# standby 1 preempt
DeviceB(config-if)# standby 1 priority 90
DeviceB(config-if)# standby 2 ip 10.0.0.12
DeviceB(config-if)# standby 2 preempt
DeviceB(config-if)# standby 2 priority 80

Additional References for FHRP—HSRP BFD Peering

Related Documents

Related Topic

Document Title

Cisco IOS commands

Cisco IOS Master Command List, All Releases

BFD

“Bidirectional Forwarding Detection” module in the IP Routing: BFD Configuration Guide

HSRP commands

Cisco IOS IP Application Services Command Reference

Troubleshooting HSRP

Hot Standby Router Protocol: Frequently Asked Questions

RFCs

RFCs

Title

RFC 2281

Cisco Hot Standby Router Protocol

Technical Assistance

Description

Link

The Cisco Support and Documentation website provides online resources to download documentation, software, and tools. Use these resources to install and configure the software and to troubleshoot and resolve technical issues with Cisco products and technologies. Access to most tools on the Cisco Support and Documentation website requires a Cisco.com user ID and password.

Click Here

Feature Information for FHRP—HSRP BFD Peering

The following table provides release information about the feature or features described in this module. This table lists only the software release that introduced support for a given feature in a given software release train. Unless noted otherwise, subsequent releases of that software release train also support that feature.

Use Cisco Feature Navigator to find information about platform support and Cisco software image support. To access Cisco Feature Navigator, go to Click Here . An account on Cisco.com is not required.

Feature Information for FHRP—HSRP BFD Peering

Feature Name

Releases

Feature Information

FHRP—HSRP BFD Peering

12.4(11)T

The FHRP-HSRP BFD Peering feature introduces Bidirectional Forwarding Detection (BFD) in the Hot Standby Router Protocol (HSRP) group member health monitoring system. Before the introduction of this feature, group member monitoring relied exclusively on HSRP multicast messages, which are relatively large and consume CPU memory. In architectures where a single interface hosts a large number of groups, there is a need for a protocol with low CPU memory consumption and processing overhead. BFD addresses this issue and offers second health monitoring (failure detection in milliseconds) at a relatively low CPU impact.

The following commands were introduced or modified by this feature: debug standby events neighbor, show standby, show standby neighbors, standby bfd, standby bfd all-interfaces.

FHRP—HSRP IPv6 BFD Peering

The FHRP—HSRP IPv6 BFD Peering feature implements BFD support for IPv6 and IPv4 HSRP groups.

Chapter 4. FHRP - HSRP Group Shutdown

- Finding Feature Information

- Information About FHRP - HSRP Group Shutdown

- How to Configure FHRP - HSRP Group Shutdown

- Configuration Examples for FHRP - HSRP Group Shutdown

- Additional References

- Feature Information for FHRP - HSRP Group Shutdown

Finding Feature Information

Your software release may not support all the features documented in this module. For the latest caveats and feature information, see Bug Search Tool and the release notes for your platform and software release. To find information about the features documented in this module, and to see a list of the releases in which each feature is supported, see the feature information table.

Use Cisco Feature Navigator to find information about platform support and Cisco software image support. To access Cisco Feature Navigator, go to Click Here . An account on Cisco.com is not required.

Information About FHRP - HSRP Group Shutdown

- How Object Tracking Affects the Priority of an HSRP Device

- HSRP Object Tracking

- HSRP Group Shutdown

How Object Tracking Affects the Priority of an HSRP Device

The priority of a device can change dynamically if it has been configured for object tracking and the object that is being tracked goes down. The tracking process periodically polls the tracked objects and notes any change of value. The changes in the tracked object are communicated to HSRP, either immediately or after a specified delay. The object values are reported as either up or down. Examples of objects that can be tracked are the line protocol state of an interface or the reachability of an IP route. If the specified object goes down, the HSRP priority is reduced. The HSRP device with the higher priority can become the active device if it has the standby preempt command configured.

HSRP Object Tracking

Object tracking separates the tracking mechanism from HSRP and creates a separate standalone tracking process that can be used by any other process as well as HSRP. The priority of a device can change dynamically when it has been configured for object tracking and the object that is being tracked goes down. Examples of objects that can be tracked are the line protocol state of an interface or the reachability of an IP route. If the specified object goes down, the HSRP priority is reduced.

A client process such as HSRP, Virtual Router Redundancy Protocol (VRRP), or Gateway Load Balancing Protocol (GLBP) can register its interest in tracking objects and then be notified when the tracked object changes state.

For more information about object tracking, see the "Configuring Enhanced Object Tracking" document.

HSRP Group Shutdown

The FHRP—HSRP Group Shutdown feature enables you to configure an HSRP group to become disabled (its state changed to Init) instead of having its priority decremented when a tracked object goes down. Use the standby track command with the shutdown keyword to configure HSRP group shutdown.

If an object is already being tracked by an HSRP group, you cannot change the configuration to use the HSRP Group Shutdown feature. You must first remove the tracking configuration using the no standby track command and then reconfigure it using the standby track command with the shutdown keyword.

How to Configure FHRP - HSRP Group Shutdown

- Configuring HSRP Object Tracking

- Configuring HSRP MD5 Authentication Using a Key String

Configuring HSRP Object Tracking

Perform this task to configure HSRP to track an object and change the HSRP priority based on the state of the object.

Each tracked object is identified by a unique number that is specified on the tracking CLI. Client processes use this number to track a specific object.

SUMMARY STEPS

1.    enable

2.    configure terminal

3.    track object-number interface type number {line-protocol | ip routing}

4.    exit

5.    interface type number

6.    standby [group-number] track object-number [decrement priority-decrement] [shutdown]

7.    standby [group-number] ip [ip-address [secondary]]

8.    end

9.    show track [object-number | brief] [interface [brief] | ip route [brief] | resolution | timers]

DETAILED STEPS

Command or Action

Purpose

Step 1

enable

Example:

Device> enable

Enables privileged EXEC mode.

- Enter your password if prompted.

Step 2

configure terminal

Example:

Device# configure terminal

Enters global configuration mode.

Step 3

track object-number interface type number {line-protocol | ip routing}

Example:

Device(config)# track 100 interface GigabitEthernet 0/0/0 line-protocol

Configures an interface to be tracked and enters tracking configuration mode.

Step 4

exit

Example:

Device(config-track)# exit

Returns to global configuration mode.

Step 5

interface type number

Example:

Device(config)# interface GigabitEthernet 0/0/0

Configures an interface type and enters interface configuration mode.

Step 6

standby [group-number] track object-number [decrement priority-decrement] [shutdown]

Example:

Device(config-if)# standby 1 track 100 decrement 20

Configures HSRP to track an object and change the Hot Standby priority on the basis of the state of the object.

- By default, the priority of the device is decreased by 10 if a tracked object goes down. Use the decrement priority-decrement keyword and argument combination to change the default behavior.

- When multiple tracked objects are down and priority-decrement values have been configured, these configured priority decrements are cumulative. If tracked objects are down, but none of them were configured with priority decrements, the default decrement is 10 and it is cumulative.

- Use the shutdown keyword to disable the HRSP group on the device when the tracked object goes down.

Note:
If an object is already being tracked by an HSRP group, you cannot change the configuration to use the HSRP Group Shutdown feature. You must first remove the tracking configuration using the no standby track command and then reconfigure it using the standby track command with the shutdown keyword.

Step 7

standby [group-number] ip [ip-address [secondary]]

Example:

Device(config-if)# standby 1 ip 10.10.10.0

Activates HSRP.

- The default group number is 0. The group number range is from 0 to 255 for HSRP version 1 and from 0 to 4095 for HSRP version 2.

Step 8

end

Example:

Device(config-if)# end

Returns to privileged EXEC mode.

Step 9

show track [object-number | brief] [interface [brief] | ip route [brief] | resolution | timers]

Example:

Device# show track 100 interface

Displays tracking information.

Configuring HSRP MD5 Authentication Using a Key String

Note

Text authentication cannot be combined with MD5 authentication for an HSRP group at any one time. When MD5 authentication is configured, the text authentication field in HSRP hello messages is set to all zeroes on transmit and ignored on receipt, provided the receiving device also has MD5 authentication enabled.

Note

If you are changing a key string in a group of devices, change the active device last to prevent any HSRP state change. The active device should have its key string changed no later than one hold-time period, specified by the standy timers interface configuration command, after the nonactive devices. This procedure ensures that the nonactive devices do not time out the active device.

SUMMARY STEPS

1.    enable

2.    configure terminal

3.    terminal interface type number

4.    ip address ip-address mask [secondary]

5.    standby [group-number] priority priority

6.    standby [group-number] preempt [delay {minimum | reload | sync} seconds]

7.    standby [group-number] authentication md5 key-string [0 | 7] key [timeout seconds]

8.    standby [group-number] ip [ip-address] [secondary]]

9.    Repeat Steps 1 through 8 on each device that will communicate.

10.    end

11.    show standby

DETAILED STEPS

Command or Action

Purpose

Step 1

enable

Example:

Device> enable

Enables privileged EXEC mode.

- Enter your password if prompted.

Step 2

configure terminal

Example:

Device# configure terminal

Enters global configuration mode.

Step 3

terminal interface type number

Example:

Device(config)# interface GigabitEthernet 0/0/0

Configures an interface type and enters interface configuration mode.

Step 4

ip address ip-address mask [secondary]

Example:

Device(config-if)# ip address 10.0.0.1 255.255.255.0

Specifies a primary or secondary IP address for an interface.

Step 5

standby [group-number] priority priority

Example:

Device(config-if)# standby 1 priority 110

Configures HSRP priority.

Step 6

standby [group-number] preempt [delay {minimum | reload | sync} seconds]

Example:

Device(config-if)# standby 1 preempt

Configures HSRP preemption.

Step 7

standby [group-number] authentication md5 key-string [0 | 7] key [timeout seconds]

Example:

Device(config-if)# standby 1 authentication md5 key-string d00b4r987654321a timeout 30

Configures an authentication string for HSRP MD5 authentication.

- The key argument can be up to 64 characters in length. We recommended that at least 16 characters be used.

- No prefix to the key argument or specifying 0 means the key will be unencrypted.

- Specifying 7 means the key will be encrypted. The key-string authentication key will automatically be encrypted if the service password-encryption global configuration command is enabled.

- The timeout value is the period of time that the old key string will be accepted to allow configuration of all routers in a group with a new key.

Step 8

standby [group-number] ip [ip-address] [secondary]]

Example:

Device(config-if)# standby 1 ip 10.0.0.3

Activates HSRP.

Step 9

Repeat Steps 1 through 8 on each device that will communicate.

—

Step 10

end

Example:

Device(config-if)# end

Returns to privileged EXEC mode.

Step 11

show standby

Example:

Device# show standby

(Optional) Displays HSRP information.

- Use this command to verify your configuration. The key string or key chain will be displayed if configured.

Configuration Examples for FHRP - HSRP Group Shutdown

- Example: Configuring HSRP Object Tracking

- Example: Configuring HSRP Group Shutdown

Example: Configuring HSRP Object Tracking

In the following example, the tracking process is configured to track the IP-routing capability of serial interface 1/0. HSRP on Gigabit Ethernet interface 0/0/0 then registers with the tracking process to be informed of any changes to the IP-routing state of serial interface 1/0. If the IP state on serial interface 1/0 goes down, the priority of the HSRP group is reduced by 10.

If both serial interfaces are operational, Device A will be the HSRP active device because it has the higher priority. However, if IP routing on serial interface 1/0 in Device A fails, the HSRP group priority will be reduced and Device B will take over as the active device, thus maintaining a default virtual gateway service to hosts on the 10.1.0.0 subnet.

Device A Configuration

Device(config)# track 100 interface serial 1/0/0 ip routing
!
Device(config)# interface GigabitEthernet 0/0/0
Device(config-if)# ip address 10.1.0.21 255.255.0.0
Device(config-if)# standby 1 preempt
Device(config-if)# standby 1 priority 110
Device(config-if)# standby 1 track 100 decrement 10
Device(config-if)# standby 1 ip 10.1.0.1

Device B Configuration

Device(config)# track 100 interface serial 1/0/0 ip routing
!
Device(config)# interface GigabitEthernet 0/0/0
Device(config-if)# ip address 10.1.0.22 255.255.0.0
Device(config-if)# standby 1 preempt
Device(config-if)# standby 1 priority 105
Device(config-if)# standby 1 track 100 decrement 10
Device(config-if)# standby 1 ip 10.1.0.1

Example: Configuring HSRP Group Shutdown

In the following example, the tracking process is configured to track the IP-routing capability of Gigabit Ethernet interface 0/0/0. HSRP on Gigabit Ethernet interface 0/0/1 then registers with the tracking process to be informed of any changes to the IP-routing state of Gigabit Ethernet interface 0/0/0. If the IP state on Gigabit Ethernet interface 0/0/0 goes down, the HSRP group is disabled.

If both Gigabit Ethernet interfaces are operational, Device A will be the HSRP active device because it has the higher priority. However, if IP routing on Gigabit Ethernet interface 0/0/0 in Device A fails, the HSRP group will be disabled and Device B will take over as the active device, thus maintaining a default virtual gateway service to hosts on the 10.1.0.0 subnet.

Device A Configuration

Device(config)# track 100 interface GigabitEthernet 0/0/0 ip routing
!
Device(config)# interface GigabitEthernet 0/0/1
Device(config-if)# ip address 10.1.0.21 255.255.0.0
Device(config-if)# standby 1 ip 10.1.0.1
Device(config-if)# standby 1 preempt
Device(config-if)# standby 1 priority 110
Device(config-if)# standby 1 track 100 shutdown

Device B Configuration

Device(config)# track 100 interface GigabitEthernet 0/0/0 ip routing
!
Device(config)# interface GigabitEthernet 0/0/1
Device(config-if)# ip address 10.1.0.22 255.255.0.0
Device(config-if)# standby 1 ip 10.1.0.1
Device(config-if)# standby 1 preempt
Device(config-if)# standby 1 priority 105
Device(config-if)# standby 1 track 100 shutdown

If an object is already being tracked by an HSRP group, you cannot change the configuration to use the HSRP Group Shutdown feature. You must first remove the tracking configuration using the no standby track command and then reconfigure it using the standby track command with the shutdown keyword.

The following example shows how to change the configuration of a tracked object to include the HSRP Group Shutdown feature:

Device(config)# no standby 1 track 100 decrement 10
Device(config)# standby 1 track 100 shutdown

Additional References

Related Documents

Related Topic

Document Title

Cisco IOS commands

Cisco IOS Master Commands List, All Releases

HSRP commands: complete command syntax, command mode, command history, defaults, usage guidelines, and examples

Cisco IOS First Hop redundancy Protocols Command Reference

HSRP for IPv6

“HSRP for IPv6” module

Troubleshooting HSRP

Hot Standby Router Protocol: Frequently Asked Questions

Standards

Standards

Title

No new or modified standards are supported by this feature, and support for existing standards has not been modified by this feature.

--

MIBs

MIBs

MIBs Link

CISCO-HSRP-MIB CISCO-HSRP-EXT-MIB

To locate and download MIBs for selected platforms, Cisco software releases, and feature sets, use Cisco MIB Locator found at the following URL:

Click Here

RFCs

RFCs

Title

RFC 792

Internet Control Message Protocol

RFC 1828

IP Authentication Using Keyed MD5

RFC 2281

Cisco Hot Standby Router Protocol

Technical Assistance

Description

Link

The Cisco Support and Documentation website provides online resources to download documentation, software, and tools. Use these resources to install and configure the software and to troubleshoot and resolve technical issues with Cisco products and technologies. Access to most tools on the Cisco Support and Documentation website requires a Cisco.com user ID and password.

Click Here

Feature Information for FHRP - HSRP Group Shutdown

The following table provides release information about the feature or features described in this module. This table lists only the software release that introduced support for a given feature in a given software release train. Unless noted otherwise, subsequent releases of that software release train also support that feature.

Use Cisco Feature Navigator to find information about platform support and Cisco software image support. To access Cisco Feature Navigator, go to Click Here . An account on Cisco.com is not required.

Feature Information for FHRP—HSRP Group Shutdown

Feature Name

Releases

Feature Information

FHRP—HSRP Group Shutdown

12.4(9)T

12.2(33)SRC

12.2(33)SXI

12.2(50)SY

15.0(1)S

15.0(1)SY

Cisco IOS XE Release 2.1

The FHRP—HSRP Group Shutdown feature enables you to configure an HSRP group to become disabled (its state changed to Init) instead of having its priority decremented when a tracked object goes down.

The following commands were modified by this feature:standby track, show standby.

Chapter 5. FHRP - HSRP MIB

- Finding Feature Information

- Information About FHRP - HSRP MIB

- How to Configure FHRP - HSRP MIB

- Configuration Examples for FHRP - HSRP MIB

- Additional References

- Feature Information for FHRP - HSRP-MIB

Finding Feature Information

Your software release may not support all the features documented in this module. For the latest caveats and feature information, see Bug Search Tool and the release notes for your platform and software release. To find information about the features documented in this module, and to see a list of the releases in which each feature is supported, see the feature information table.

Use Cisco Feature Navigator to find information about platform support and Cisco software image support. To access Cisco Feature Navigator, go to Click Here . An account on Cisco.com is not required.

Information About FHRP - HSRP MIB

- HSRP MIB Traps

HSRP MIB Traps

HSRP MIB supports Simple Network Management Protocol (SNMP) Get operations, to allow network devices to get reports about HSRP groups in a network from the network management station.

Enabling HSRP MIB trap support is performed through the CLI, and the MIB is used for getting the reports. A trap notifies the network management station when a device leaves or enters the active or standby state. When an entry is configured from the CLI, the RowStatus for that group in the MIB immediately goes to the active state.

Cisco software supports a read-only version of the MIB, and set operations are not supported.

This functionality supports four MIB tables, as follows:

- cHsrpGrpEntry table defined in CISCO-HSRP-MIB.my

- cHsrpExtIfTrackedEntry, defined in CISCO-HSRP-EXT-MIB.my

- cHsrpExtSecAddrEntry, defined in CISCO-HSRP-EXT-MIB.my

- cHsrpExtIfEntry defined in CISCO-HSRP-EXT-MIB.my

The cHsrpGrpEntry table consists of all the group information defined in RFC 2281, Cisco Hot Standby Router Protocol; the other tables consist of the Cisco extensions to RFC 2281, which are defined in CISCO-HSRP-EXT-MIB.my.

How to Configure FHRP - HSRP MIB

- Enabling HSRP MIB Traps

Enabling HSRP MIB Traps

SUMMARY STEPS

1.    enable

2.    configure terminal

3.    snmp-server enable traps hsrp

4.    snmp-server host host community-string hsrp

DETAILED STEPS

Command or Action

Purpose

Step 1

enable

Example:

Device> enable

Enables privileged EXEC mode.

- Enter your password if prompted.

Step 2

configure terminal

Example:

Device# configure terminal

Enters global configuration mode.

Step 3

snmp-server enable traps hsrp

Example:

Device(config)# snmp-server enable traps hsrp

Enables the device to send SNMP traps and informs, and HSRP notifications.

Step 4

snmp-server host host community-string hsrp

Example:

Device(config)# snmp-server host myhost.comp.com public hsrp

Specifies the recipient of an SNMP notification operation, and that HSRP notifications be sent to the host.

Configuration Examples for FHRP - HSRP MIB

- Example: Enabling HSRP MIB Traps

Example: Enabling HSRP MIB Traps

The following examples show how to configure HSRP on two devices and enable the HSRP MIB trap support functionality. As in many environments, one device is preferred as the active one. To configure a device’s preference as the active device, configure the device at a higher priority level and enable preemption. In the following example, the active device is referred to as the primary device. The second device is referred to as the backup device:

Device A

Device(config)# interface GigabitEthernet 0/0/0
Device(config-if)# ip address 10.1.1.1 255.255.0.0
Device(config-if)# standby priority 200
Device(config-if)# standby preempt
Device(config-if)# standby ip 10.1.1.3
Device(config-if)# exit
Device(config)# snmp-server enable traps hsrp
Device(config)# snmp-server host yourhost.cisco.com public hsrp

Device B

Device(config)#interface GigabitEthernet 1/0/0
Device(config-if)# ip address 10.1.1.2 255.255.0.0
Device(config-if)#  standby priority 101
Device(config-if)# standby ip 10.1.1.3
Device(config-if)# exit
Device(config)# snmp-server enable traps hsrp
Device(config)# snmp-server host myhost.cisco.com public hsrp

Additional References

Related Documents

Related Topic

Document Title

Cisco IOS commands

Cisco IOS Master Commands List, All Releases

HSRP commands: complete command syntax, command mode, command history, defaults, usage guidelines, and examples

Cisco IOS First Hop redundancy Protocols Command Reference

HSRP for IPv6

“HSRP for IPv6” module

Troubleshooting HSRP

Hot Standby Router Protocol: Frequently Asked Questions

Standards

Standards

Title

No new or modified standards are supported by this feature, and support for existing standards has not been modified by this feature.

--

MIBs

MIBs

MIBs Link

CISCO-HSRP-MIB CISCO-HSRP-EXT-MIB

To locate and download MIBs for selected platforms, Cisco software releases, and feature sets, use Cisco MIB Locator found at the following URL:

Click Here

RFCs

RFCs

Title

RFC 792

Internet Control Message Protocol

RFC 1828

IP Authentication Using Keyed MD5

RFC 2281

Cisco Hot Standby Router Protocol

Technical Assistance

Description

Link

The Cisco Support and Documentation website provides online resources to download documentation, software, and tools. Use these resources to install and configure the software and to troubleshoot and resolve technical issues with Cisco products and technologies. Access to most tools on the Cisco Support and Documentation website requires a Cisco.com user ID and password.

Click Here

Feature Information for FHRP - HSRP-MIB

The following table provides release information about the feature or features described in this module. This table lists only the software release that introduced support for a given feature in a given software release train. Unless noted otherwise, subsequent releases of that software release train also support that feature.

Use Cisco Feature Navigator to find information about platform support and Cisco software image support. To access Cisco Feature Navigator, go to Click Here . An account on Cisco.com is not required.

Feature Information for FHRP—HSRP-MIB

Feature Name

Releases

Feature Information

FHRP—HSRP-MIB

12.0(3)T

12.0(12)S

Cisco IOS XE Release 2.1

The FHRP—HSRP-MIB feature introduces support for the CISCO-HRSP-MIB.

Chapter 6. HSRP MD5 Authentication

- Finding Feature Information

- Information About HSRP MD5 Authentication

- How to Configure HSRP MD5 Authentication

- Configuration Examples for HSRP MD5 Authentication

- Additional References

- Feature Information for HSRP MD5 Authentication

Finding Feature Information

Your software release may not support all the features documented in this module. For the latest caveats and feature information, see Bug Search Tool and the release notes for your platform and software release. To find information about the features documented in this module, and to see a list of the releases in which each feature is supported, see the feature information table.

Use Cisco Feature Navigator to find information about platform support and Cisco software image support. To access Cisco Feature Navigator, go to Click Here . An account on Cisco.com is not required.

Information About HSRP MD5 Authentication

- HSRP Text Authentication

- HSRP MD5 Authentication

HSRP Text Authentication

HSRP ignores unauthenticated HSRP protocol messages. The default authentication type is text authentication.

HSRP authentication protects against false HSRP hello packets causing a denial-of-service attack. For example, Device A has a priority of 120 and is the active device. If a host sends spoof HSRP hello packets with a priority of 130, then Device A stops being the active device. If Device A has authentication configured such that the spoof HSRP hello packets are ignored, Device A will remain the active device

HSRP packets will be rejected in any of the following cases:

- The authentication schemes differ on the device and in the incoming packets.

- Text authentication strings differ on the device and in the incoming packet.

HSRP MD5 Authentication

Before the introduction of HSRP MD5 authentication, HSRP authenticated protocol packets with a simple plain text string. HSRP MD5 authentication is an enhancement to generate an MD5 digest for the HSRP portion of the multicast HSRP protocol packet. This functionality provides added security and protects against the threat from HSRP-spoofing software.

MD5 authentication provides greater security than the alternative plain text authentication scheme. MD5 authentication allows each HSRP group member to use a secret key to generate a keyed MD5 hash that is part of the outgoing packet. A keyed hash of an incoming packet is generated and if the hash within the incoming packet does not match the generated hash, the packet is ignored.

The key for the MD5 hash can be either given directly in the configuration using a key string or supplied indirectly through a key chain.

HSRP has two authentication schemes:

- Plain text authentication

- MD5 authentication

HSRP authentication protects against false HSRP hello packets causing a denial-of-service attack. For example, Device A has a priority of 120 and is the active device. If a host sends spoof HSRP hello packets with a priority of 130, then Device A stops being the active device. If Device A has authentication configured such that the spoof HSRP hello packets are ignored, Device A will remain the active device.

HSRP packets will be rejected in any of the following cases:

- The authentication schemes differ on the device and in the incoming packets.

- MD5 digests differ on the device and in the incoming packet.

- Text authentication strings differ on the device and in the incoming packet.

How to Configure HSRP MD5 Authentication

- Configuring HSRP MD5 Authentication Using a Key Chain

- Troubleshooting HSRP MD5 Authentication

- Configuring HSRP Text Authentication

Configuring HSRP MD5 Authentication Using a Key Chain

Perform this task to configure HSRP MD5 authentication using a key chain. Key chains allow a different key string to be used at different times according to the key chain configuration. HSRP will query the appropriate key chain to obtain the current live key and key ID for the specified key chain.

SUMMARY STEPS

1.    enable

2.    configure terminal

3.    key chain name-of-chain

4.    key key-id

5.    key-string string

6.    exit

7.    exit

8.    interface type number

9.    ip address ip-address mask [secondary]

10.    standby [group-number] priority priority

11.    standby [group-number] preempt [delay {minimum | reload | sync} seconds]

12.    standby [group-number] authentication md5 key-chain key-chain-name

13.    standby [group-number] ip [ip-address [secondary]]

14.    Repeat Steps 1 through 12 on each device that will communicate.

15.    end

16.    show standby

DETAILED STEPS

Command or Action

Purpose

Step 1

enable

Example:

Device> enable

Enables privileged EXEC mode.

- Enter your password if prompted.

Step 2

configure terminal

Example:

Device# configure terminal

Enters global configuration mode.

Step 3

key chain name-of-chain

Example:

Device(config)# key chain hsrp1

Enables authentication for routing protocols, identifies a group of authentication keys, and enters key-chain configuration mode.

Step 4

key key-id

Example:

Device(config-keychain)# key 100

Identifies an authentication key on a key chain and enters key-chain key configuration mode.

- The value for thekey-id argument must be a number.

Step 5

key-string string

Example:

Device(config-keychain-key)# key-string mno172

Specifies the authentication string for a key.

- The value for the string argument can be 1 to 80 uppercase or lowercase alphanumeric characters; the first character cannot be a numeral

Step 6

exit

Example:

Device(config-keychain-key)# exit

Returns to key-chain configuration mode.

Step 7

exit

Example:

Device(config-keychain)# exit

Returns to global configuration mode.

Step 8

interface type number

Example:

Device(config)# interface GigabitEthernet 0/0/0

Configures an interface type and enters interface configuration mode.

Step 9

ip address ip-address mask [secondary]

Example:

Device(config-if)# ip address 10.21.8.32 255.255.255.0

Specifies a primary or secondary IP address for an interface.

Step 10

standby [group-number] priority priority

Example:

Device(config-if)# standby 1 priority 110

Configures HSRP priority.

Step 11

standby [group-number] preempt [delay {minimum | reload | sync} seconds]

Example:

Device(config-if)# standby 1 preempt

Configures HSRP preemption.

Step 12

standby [group-number] authentication md5 key-chain key-chain-name

Example:

Device(config-if)# standby 1 authentication md5 key-chain hsrp1

Configures an authentication MD5 key chain for HSRP MD5 authentication.

- The key chain name must match the name specified in Step 3.

Step 13

standby [group-number] ip [ip-address [secondary]]

Example:

Device(config-if)# standby 1 ip 10.21.8.12

Activates HSRP.

Step 14

Repeat Steps 1 through 12 on each device that will communicate.

—

Step 15

end

Example:

Device(config-if)# end

Returns to privileged EXEC mode.

Step 16

show standby

Example:

Device# show standby

(Optional) Displays HSRP information.

- Use this command to verify your configuration. The key string or key chain will be displayed if configured.

Troubleshooting HSRP MD5 Authentication

Perform this task if HSRP MD5 authentication is not operating correctly.

SUMMARY STEPS

1.    enable

2.    debug standby errors

DETAILED STEPS

Command or Action

Purpose

Step 1

enable

Example:

Device> enable

Enables privileged EXEC mode.

- Enter your password if prompted.

Step 2

debug standby errors

Example:

Device# debug standby errors

Displays error messages related to HSRP.

- Error messages will be displayed for each packet that fails to authenticate, so use this command with care.

Examples

In the following example, Device A has MD5 text string authentication configured, but Device B has the default text authentication:

Device# debug standby errors

A:Jun 16 12:14:50.337:HSRP:Et0/1 Grp 0 Auth failed for Hello pkt from 10.21.0.5, MD5 confgd but no tlv
B:Jun 16 12:16:34.287:HSRP:Et0/1 Grp 0 Auth failed for Hello pkt from 10.21.0.4, Text auth failed

In the following example, both Device A and Device B have different MD5 authentication strings:

Device# debug standby errors

A:Jun 16 12:19:26.335:HSRP:Et0/1 Grp 0 Auth failed for Hello pkt from 10.21.0.5, MD5 auth failed
B:Jun 16 12:18:46.280:HSRP:Et0/1 Grp 0 Auth failed for Hello pkt from 10.21.0.4, MD5 auth failed

Configuring HSRP Text Authentication

SUMMARY STEPS

1.    enable

2.    configure terminal

3.    interface type number

4.    ip address ip-address mask [secondary]

5.    standby [group-number] priority priority

6.    standby [group-number] preempt [delay {minimum | reload | sync} seconds]

7.    standby [group-number] authentication text string

8.    standby [group-number] ip [ip-address [secondary]]

9.    Repeat Steps 1 through 8 on each device that will communicate.

10.    end

11.    show standby

DETAILED STEPS

Command or Action

Purpose

Step 1

enable

Example:

Device> enable

Enables privileged EXEC mode.

- Enter your password if prompted.

Step 2

configure terminal

Example:

Device# configure terminal

Enters global configuration mode.

Step 3

interface type number

Example:

Device(config)# interface GigabitEthernet 0/0/0

Configures an interface type and enters interface configuration mode.

Step 4

ip address ip-address mask [secondary]

Example:

Device(config-if)# ip address 10.0.0.1 255.255.255.0

Specifies a primary or secondary IP address for an interface.

Step 5

standby [group-number] priority priority

Example:

Device(config-if)# standby 1 priority 110

Configures HSRP priority.

Step 6

standby [group-number] preempt [delay {minimum | reload | sync} seconds]

Example:

Device(config-if)# standby 1 preempt

Configures HSRP preemption.

Step 7

standby [group-number] authentication text string

Example:

Device(config-if)# standby 1 authentication text authentication1

Configures an authentication string for HSRP text authentication.

- The default string is cisco.

Step 8

standby [group-number] ip [ip-address [secondary]]

Example:

Device(config-if)# standby 1 ip 10.0.0.3

Activates HSRP.

Step 9

Repeat Steps 1 through 8 on each device that will communicate.

--

Step 10

end

Example:

Device(config-if)# end

Returns to privileged EXEC mode.

Step 11

show standby

Example:

Device# show standby

(Optional) Displays HSRP information.

- Use this command to verify your configuration. The key string or key chain will be displayed if configured.

Configuration Examples for HSRP MD5 Authentication

- Example: Configuring HSRP MD5 Authentication Using Key Strings

- Example: Configuring HSRP MD5 Authentication Using Key Chains

- Example: Configuring HSRP MD5 Authentication Using Key Strings and Key Chains

- Example: Configuring HSRP Text Authentication

Example: Configuring HSRP MD5 Authentication Using Key Strings

Device(config)# interface GigabitEthernet 0/0/0
Device(config-if)# standby 1 priority 110
Device(config-if)# standby 1 preempt
Device(config-if)# standby 1 authentication md5 key-string 54321098452103ab timeout 30
Device(config-if)# standby 1 ip 10.21.0.10

Example: Configuring HSRP MD5 Authentication Using Key Chains

In the following example, HSRP queries the key chain “hsrp1” to obtain the current live key and key ID for the specified key chain:

Device(config)# key chain hsrp1
Device(config-keychain)# key 1
Device(config-keychain-key)# key-string 54321098452103ab
Device(config-keychain-key)# exit
Device(config)# interface GigabitEthernet 0/0/0
Device(config-if)# standby 1 priority 110
Device(config-if)# standby 1 preempt
Device(config-if)# standby 1 authentication md5 key-chain hsrp1
Device(config-if)# standby 1 ip 10.21.0.10

Example: Configuring HSRP MD5 Authentication Using Key Strings and Key Chains

The key ID for key-string authentication is always zero. If a key chain is configured with a key ID of zero, then the following configuration will work:

Device 1

Device(config)# key chain hsrp1
Device(config-keychain)# key 0
Device(config-keychain-key)# key-string 54321098452103ab
Device(config-keychain-key)# exit
Device(config)# interface GigabitEthernet 0/0/0
Device(config-if)# standby 1 authentication md5 key-chain hsrp1
Device(config-if)# standby 1 ip 10.21.0.10

Device 2

Device(config)# interface GigabitEthernet 0/0/0
Device(config-if)# standby 1 authentication md5 key-string 54321098452103ab
Device(config-if)# standby 1 ip 10.21.0.10

Example: Configuring HSRP Text Authentication

Device(config)# interface GigabitEthernet 0/0/0
Device(config-if)# standby 1 priority 110
Device(config-if)# standby 1 preempt
Device(config-if)# standby 1 authentication text company2
Device(config-if)# standby 1 ip 10.21.0.10

Additional References

Related Documents

Related Topic

Document Title

Cisco IOS commands

Cisco IOS Master Commands List, All Releases

HSRP commands: complete command syntax, command mode, command history, defaults, usage guidelines, and examples

Cisco IOS First Hop redundancy Protocols Command Reference

HSRP for IPv6

“HSRP for IPv6” module

Troubleshooting HSRP

Hot Standby Router Protocol: Frequently Asked Questions

Standards

Standards

Title

No new or modified standards are supported by this feature, and support for existing standards has not been modified by this feature.

--

MIBs

MIBs

MIBs Link

CISCO-HSRP-MIB CISCO-HSRP-EXT-MIB

To locate and download MIBs for selected platforms, Cisco software releases, and feature sets, use Cisco MIB Locator found at the following URL:

Click Here

RFCs

RFCs

Title

RFC 792

Internet Control Message Protocol

RFC 1828

IP Authentication Using Keyed MD5

RFC 2281

Cisco Hot Standby Router Protocol

Technical Assistance

Description

Link

The Cisco Support and Documentation website provides online resources to download documentation, software, and tools. Use these resources to install and configure the software and to troubleshoot and resolve technical issues with Cisco products and technologies. Access to most tools on the Cisco Support and Documentation website requires a Cisco.com user ID and password.

Click Here

Feature Information for HSRP MD5 Authentication

The following table provides release information about the feature or features described in this module. This table lists only the software release that introduced support for a given feature in a given software release train. Unless noted otherwise, subsequent releases of that software release train also support that feature.

Use Cisco Feature Navigator to find information about platform support and Cisco software image support. To access Cisco Feature Navigator, go to Click Here . An account on Cisco.com is not required.

Feature Information for HSRP MD5 Authentication

Feature Name

Releases

Feature Information

HSRP MD5 Authentication

12.2(25)S

12.2(33)SRA

12.2(33)SXH

12.2(50)SY

12.3(2)T

15.0(1)S

15.0(1)SY

Cisco IOS XE Release 2.1

Cisco IOS XE 3.1.0SG

Cisco IOS XE Release 3.9S

Prior to the introduction of the HSRP MD5 Authentication feature, HSRP authenticated protocol packets with a simple plain text string. The HSRP MD5 Authentication feature is an enhancement to generate an MD5 digest for the HSRP portion of the multicast HSRP protocol packet. This feature provides added security and protects against the threat from HSRP-spoofing software.

The following commands were introduced or modified by this feature: show standby, standby authentication.

Chapter 7. HSRP Support for ICMP Redirects

- Finding Feature Information

- Information About HSRP Support for ICMP Redirects

- How to Configure HSRP Support for ICMP Redirects

- Configuration Examples for HSRP Support for ICMP Redirects

- Additional References

- Feature Information for HSRP Support for ICMP Redirects

Finding Feature Information

Your software release may not support all the features documented in this module. For the latest caveats and feature information, see Bug Search Tool and the release notes for your platform and software release. To find information about the features documented in this module, and to see a list of the releases in which each feature is supported, see the feature information table.

Use Cisco Feature Navigator to find information about platform support and Cisco software image support. To access Cisco Feature Navigator, go to Click Here . An account on Cisco.com is not required.

Information About HSRP Support for ICMP Redirects

- HSRP Support for ICMP Redirect Messages

- ICMP Redirects to Active HSRP Devices

- ICMP Redirects to Passive HSRP Devices

- ICMP Redirects to Non-HSRP Devices

- Passive HSRP Advertisement Messages

- ICMP Redirects Not Sent

HSRP Support for ICMP Redirect Messages

By default, HSRP filtering of Internet Control Message Protocol (ICMP) redirect messages is enabled on devices running HSRP.

ICMP is a network layer Internet protocol that provides message packets to report errors and other information relevant to IP processing. ICMP can send error packets to a host and can send redirect packets to a host.

When HSRP is running, preventing hosts from discovering the interface (or real) IP addresses of devices in the HSRP group is important. If a host is redirected by ICMP to the real IP address of a device, and that device later fails, then packets from the host will be lost.

ICMP redirect messages are automatically enabled on interfaces configured with HSRP. This functionality works by filtering outgoing ICMP redirect messages through HSRP, where the next hop IP address may be changed to an HSRP virtual IP address.

ICMP Redirects to Active HSRP Devices

The next-hop IP address is compared to the list of active HSRP devices on that network; if a match is found, then the real next-hop IP address is replaced with a corresponding virtual IP address and the redirect message is allowed to continue.

If no match is found, then the ICMP redirect message is sent only if the device corresponding to the new next hop IP address is not running HSRP. Redirects to passive HSRP devices are not allowed (a passive HSRP device is a device running HSRP, but which contains no active HSRP groups on the interface).

For optimal operation, every device in a network that is running HSRP should contain at least one active HSRP group on an interface to that network. Every HSRP device need not be a member of the same group. Each HSRP device will snoop on all HSRP packets on the network to maintain a list of active devices (virtual IP addresses versus real IP addresses).

Consider the network shown in the figure below, which supports the HSRP ICMP redirection filter.

Network Supporting the HSRP ICMP Redirection Filter

If the host wants to send a packet to another host on Net D, then it first sends it to its default gateway, the virtual IP address of HSRP group 1.

The following is the packet received from the host:

dest MAC         = HSRP group 1 virtual MAC
source MAC       = Host MAC
dest IP          = host-on-netD IP
source IP        = Host IP

Device R1 receives this packet and determines that device R4 can provide a better path to Net D, so it prepares to send a redirect message that will redirect the host to the real IP address of device R4 (because only real IP addresses are in its routing table).

The following is the initial ICMP redirect message sent by device R1:

dest MAC         = Host MAC
source MAC       = router R1 MAC
dest IP          = Host IP
source IP        = router R1 IP
gateway to use   = router R4 IP

Before this redirect occurs, the HSRP process of device R1 determines that device R4 is the active HSRP device for group 3, so it changes the next hop in the redirect message from the real IP address of device R4 to the virtual IP address of group 3. Furthermore, it determines from the destination MAC address of the packet that triggered the redirect message that the host used the virtual IP address of group 1 as its gateway, so it changes the source IP address of the redirect message to the virtual IP address of group 1.

The modified ICMP redirect message showing the two modified fields (*) is as follows:

dest MAC         = Host MAC
source MAC       = router R1 MAC
dest IP          = Host IP
source IP*       = HSRP group 1 virtual IP
gateway to use*  = HSRP group 3 virtual IP

This second modification is necessary because hosts compare the source IP address of the ICMP redirect message with their default gateway. If these addresses do not match, the ICMP redirect message is ignored. The routing table of the host now consists of the default gateway, virtual IP address of group 1, and a route to Net D through the virtual IP address of group 3.

ICMP Redirects to Passive HSRP Devices

ICMP redirects to passive HSRP devices are not permitted. Redundancy may be lost if hosts learn the real IP addresses of HSRP devices.

In the "Network Supporting the HSRP ICMP Redirection Filter" figure, redirection to device R8 is not allowed because R8 is a passive HSRP device. In this case, packets from the host to Net D will first go to device R1 and then be forwarded to device R4; that is, they will traverse the network twice.

A network configuration with passive HSRP devices is considered a misconfiguration. For HSRP ICMP redirection to operate optimally, every device on the network that is running HSRP should contain at least one active HSRP group.

ICMP Redirects to Non-HSRP Devices

ICMP redirects to devices not running HSRP on their local interface are permitted. No redundancy is lost if hosts learn the real IP address of non-HSRP devices.

In the "Network Supporting the HSRP ICMP Redirection Filter" figure, redirection to device R7 is allowed because R7 is not running HSRP. In this case, the next hop IP address is unchanged. The source IP address is changed dependent upon the destination MAC address of the original packet. You can specify the no standby redirect unknown command to stop these redirects from being sent.

Passive HSRP Advertisement Messages

Passive HSRP devices send out HSRP advertisement messages both periodically and when entering or leaving the passive state. Thus, all HSRP devices can determine the HSRP group state of any HSRP device on the network. These advertisements inform other HSRP devices on the network of the HSRP interface state, as follows:

- Active—Interface has at least one active group. A single advertisement is sent out when the first group becomes active.

- Dormant—Interface has no HSRP groups. A single advertisement is sent once when the last group is removed.

- Passive—Interface has at least one nonactive group and no active groups. Advertisements are sent out periodically.

You can adjust the advertisement interval and hold-down time using the standby redirect timers command.

ICMP Redirects Not Sent

If the HSRP device cannot uniquely determine the IP address used by the host when it sends the packet that caused the redirect, the redirect message will not be sent. The device uses the destination MAC address in the original packet to make this determination. In certain configurations, such as the use of the standby use-bia interface configuration command specified on an interface, redirects cannot be sent. In this case, the HSRP groups use the interface MAC address as their virtual MAC address. The device now cannot determine if the default gateway of the host is the real IP address or one of the HSRP virtual IP addresses that are active on the interface.

The IP source address of an ICMP packet must match the gateway address used by the host in the packet that triggered the ICMP packet, otherwise the host will reject the ICMP redirect packet. An HSRP device uses the destination MAC address to determine the gateway IP address of the host. If the HSRP device is using the same MAC address for multiple IP addresses, uniquely determining the gateway IP address of the host is not possible, and the redirect message is not sent.

The following is sample output from the debug standby events icmp EXEC command if HSRP could not uniquely determine the gateway used by the host:

10:43:08: HSRP: ICMP redirect not sent to 10.0.0.4 for dest 10.0.1.2
10:43:08: HSRP: could not uniquely determine IP address for mac 00d0.bbd3.bc22

How to Configure HSRP Support for ICMP Redirects

- Enabling HSRP Support for ICMP Redirect Messages

Enabling HSRP Support for ICMP Redirect Messages

By default, HSRP filtering of ICMP redirect messages is enabled on devices running HSRP. Perform this task to reenable this feature on your device if it is disabled.

SUMMARY STEPS

1.    enable

2.    configure terminal

3.    interface type number

4.    standby redirect [timers advertisement holddown] [unknown]

5.    end

6.    show standby redirect [ip-address] [interface-type interface-number] [active] [passive] [timers]

DETAILED STEPS

Command or Action

Purpose

Step 1

enable

Example:

Device> enable

Enables privileged EXEC mode.

- Enter your password if prompted.

Step 2

configure terminal

Example:

Device# configure terminal

Enters global configuration mode.

Step 3

interface type number

Example:

Device(config)# interface GigabitEthernet 0/0/0

Configures an interface type and enters interface configuration mode.

Step 4

standby redirect [timers advertisement holddown] [unknown]

Example:

Device(config-if)# standby redirect

Enables HSRP filtering of ICMP redirect messages.

- You can also use this command in global configuration mode, which enables HSRP filtering of ICMP redirect messages on all interfaces configured for HSRP.

Step 5

end

Example:

Device(config-if)# end

Returns to privileged EXEC mode.

Step 6

show standby redirect [ip-address] [interface-type interface-number] [active] [passive] [timers]

Example:

Device# show standby redirect

(Optional) Displays ICMP redirect information on interfaces configured with HSRP.

Configuration Examples for HSRP Support for ICMP Redirects

- Example: Configuring HSRP Support for ICMP Redirect Messages

Example: Configuring HSRP Support for ICMP Redirect Messages

Device A Configuration—Active for Group 1 and Standby for Group 2

Device(config)# interface GigabitEthernet 0/0/0
Device(config-if)# ip address 10.0.0.10 255.0.0.0
Device(config-if)# standby redirect
Device(config-if)# standby 1 priority 120
Device(config-if)# standby 1 preempt delay minimum 20
Device(config-if)# standby 1 ip 10.0.0.1
Device(config-if)# standby 2 priority 105
Device(config-if)# standby 2 preempt delay minimum 20
Device(config-if)# standby 2 ip 10.0.0.2

Device B Configuration—Standby for Group 1 and Active for Group 2

Device(config)# interface GigabitEthernet 0/0/0
Device(config-if)# ip address 10.0.0.11 255.0.0.0
Device(config-if)# standby redirect
Device(config-if)# standby 1 priority 105
Device(config-if)# standby 1 preempt delay minimum 20
Device(config-if)# standby 1 ip 10.0.0.1
Device(config-if)# standby 2 priority 120
Device(config-if)# standby 2 preempt delay minimum 20
Device(config-if)# standby 2 ip 10.0.0.2

Additional References

Related Documents

Related Topic

Document Title

Cisco IOS commands

Cisco IOS Master Commands List, All Releases

HSRP commands: complete command syntax, command mode, command history, defaults, usage guidelines, and examples

Cisco IOS First Hop redundancy Protocols Command Reference

HSRP for IPv6

“HSRP for IPv6” module

Troubleshooting HSRP

Hot Standby Router Protocol: Frequently Asked Questions

Standards

Standards

Title

No new or modified standards are supported by this feature, and support for existing standards has not been modified by this feature.

--

MIBs

MIBs

MIBs Link

CISCO-HSRP-MIB CISCO-HSRP-EXT-MIB

To locate and download MIBs for selected platforms, Cisco software releases, and feature sets, use Cisco MIB Locator found at the following URL:

Click Here

RFCs

RFCs

Title

RFC 792

Internet Control Message Protocol

RFC 1828

IP Authentication Using Keyed MD5

RFC 2281

Cisco Hot Standby Router Protocol

Technical Assistance

Description

Link

The Cisco Support and Documentation website provides online resources to download documentation, software, and tools. Use these resources to install and configure the software and to troubleshoot and resolve technical issues with Cisco products and technologies. Access to most tools on the Cisco Support and Documentation website requires a Cisco.com user ID and password.

Click Here

Feature Information for HSRP Support for ICMP Redirects

The following table provides release information about the feature or features described in this module. This table lists only the software release that introduced support for a given feature in a given software release train. Unless noted otherwise, subsequent releases of that software release train also support that feature.

Use Cisco Feature Navigator to find information about platform support and Cisco software image support. To access Cisco Feature Navigator, go to Click Here . An account on Cisco.com is not required.

Feature Information for HSRP Support for ICMP Redirects

Feature Name

Releases

Feature Information

HSRP Support for ICMP Redirects

12.1(3)T

12.2(50)SY

15.0(1)S

15.0(1)SY

Cisco IOS XE Release 2.1

Cisco IOS XE Release 3.9S

The HSRP support for ICMP Redirects feature enables ICMP redirection on interfaces configured with HSRP.

The following commands were introduced or modified by this feature:

debug standby event , debug standby events icmp,show standby,standby redirects

Chapter 8. HSRP Support for MPLS VPNs

- Finding Feature Information

- Information About HSRP Support for MPLS VPNs

- Additional References

- Feature Information for HSRP Support for MPLS VPNs

Finding Feature Information

Your software release may not support all the features documented in this module. For the latest caveats and feature information, see Bug Search Tool and the release notes for your platform and software release. To find information about the features documented in this module, and to see a list of the releases in which each feature is supported, see the feature information table.

Use Cisco Feature Navigator to find information about platform support and Cisco software image support. To access Cisco Feature Navigator, go to Click Here . An account on Cisco.com is not required.

Information About HSRP Support for MPLS VPNs

- HSRP Support for MPLS VPNs

HSRP Support for MPLS VPNs

HSRP support for a Multiprotocol Label Switching (MPLS) VPN interface is useful when an Ethernet LAN is connected between two provider edge (PE) devices with either of the following conditions:

- A customer edge (CE) device with a default route to the HSRP virtual IP address

- One or more hosts with the HSRP virtual IP address configured as the default gateway

Each VPN is associated with one or more VPN routing and forwarding (VRF) instances. A VRF consists of the following elements:

- IP routing table

- Cisco Express Forwarding table

- Set of interfaces that use the Cisco Express Forwarding forwarding table

- Set of rules and routing protocol parameters to control the information in the routing tables

VPN routing information is stored in the IP routing table and the Cisco Express Forwarding table for each VRF. A separate set of routing and Cisco Express Forwarding tables is maintained for each VRF. These tables prevent information from being forwarded outside a VPN and also prevent packets that are outside a VPN from being forwarded to a device within the VPN.

HSRP adds ARP entries and IP hash table entries (aliases) using the default routing table instance. However, a different routing table instance is used when VRF forwarding is configured on an interface, causing ARP and ICMP echo requests for the HSRP virtual IP address to fail.

HSRP support for MPLS VPNs ensures that the HSRP virtual IP address is added to the correct IP routing table and not to the default routing table.

Additional References

Related Documents

Related Topic

Document Title

Cisco IOS commands

Cisco IOS Master Commands List, All Releases

HSRP commands: complete command syntax, command mode, command history, defaults, usage guidelines, and examples

Cisco IOS First Hop redundancy Protocols Command Reference

HSRP for IPv6

“HSRP for IPv6” module

Troubleshooting HSRP

Hot Standby Router Protocol: Frequently Asked Questions

Standards

Standards

Title

No new or modified standards are supported by this feature, and support for existing standards has not been modified by this feature.

--

MIBs

MIBs

MIBs Link

CISCO-HSRP-MIB CISCO-HSRP-EXT-MIB

To locate and download MIBs for selected platforms, Cisco software releases, and feature sets, use Cisco MIB Locator found at the following URL:

Click Here

RFCs

RFCs

Title

RFC 792

Internet Control Message Protocol

RFC 1828

IP Authentication Using Keyed MD5

RFC 2281

Cisco Hot Standby Router Protocol

Technical Assistance

Description

Link

The Cisco Support and Documentation website provides online resources to download documentation, software, and tools. Use these resources to install and configure the software and to troubleshoot and resolve technical issues with Cisco products and technologies. Access to most tools on the Cisco Support and Documentation website requires a Cisco.com user ID and password.

Click Here

Feature Information for HSRP Support for MPLS VPNs

The following table provides release information about the feature or features described in this module. This table lists only the software release that introduced support for a given feature in a given software release train. Unless noted otherwise, subsequent releases of that software release train also support that feature.

Use Cisco Feature Navigator to find information about platform support and Cisco software image support. To access Cisco Feature Navigator, go to Click Here . An account on Cisco.com is not required.

Feature Information for HSRP Support for MPLS VPNs

Feature Name

Releases

Feature Information

HSRP Support for MPLS VPNs

12.0(23)S

12.0(17)ST

12.2(28)SB

12.2(17b)SXA

12.2(8)T

12.2(50)SY

15.0(1)S

15.0(1)SY

Cisco IOS XE Release 2.1

HSRP support for a Multiprotocol Label Switching (MPLS) Virtual Private Network (VPN) interface is useful when an Ethernet LAN is connected between two provider edge (PE) devices under certain conditions.

There are no new or modified commands for this feature.

Chapter 9. FHRP - HSRP Multiple Group Optimization

- Finding Feature Information

- Information About FHRP - Multiple Group Optimization

- How to configure FHRP - Multiple Group Optimization

- Configuration Examples for FHRP - Multiple Group Optimization

- Additional References

- Feature Information for FHRP - HSRP Multiple Group Optimization

Finding Feature Information

Your software release may not support all the features documented in this module. For the latest caveats and feature information, see Bug Search Tool and the release notes for your platform and software release. To find information about the features documented in this module, and to see a list of the releases in which each feature is supported, see the feature information table.

Use Cisco Feature Navigator to find information about platform support and Cisco software image support. To access Cisco Feature Navigator, go to Click Here . An account on Cisco.com is not required.

Information About FHRP - Multiple Group Optimization

- HSRP Multiple Group Optimization

HSRP Multiple Group Optimization

The configuration of many hundreds of subinterfaces on the same physical interface, with each subinterface having its own HSRP group, can cause the processes of negotiation and maintenance of multiple HSRP groups to have a detrimental impact on network traffic and CPU utilization.

Only one HSRP group is required on a physical interface for the purposes of electing active and standby devices. This group is known as the master group. Other HSRP groups may be created on each subinterface and linked to the master group via the group name. These linked HSRP groups are known as client or slave groups.

The HSRP group state of the client groups follows that of the master group. Client groups do not participate in any sort of device election mechanism.

Client groups send periodic messages in order to refresh their virtual MAC addresses in switches and learning bridges. The refresh message may be sent at a much lower frequency compared with the protocol election messages sent by the master group.

How to configure FHRP - Multiple Group Optimization

- Configuring Multiple HSRP Groups for Load Balancing

- Improving CPU and Network Performance with HSRP Multiple Group Optimization

Configuring Multiple HSRP Groups for Load Balancing

Perform this task to configure multiple HSRP groups for load balancing.

Multiple HSRP groups enable redundancy and load-sharing within networks and allow redundant devices to be more fully utilized. A device actively forwarding traffic for one HSRP group can be in standby or in the listen state for another group.

If two devices are used, then Device A would be configured as active for group 1 and standby for group 2. Device B would be standby for group 1 and active for group 2. Fifty percent of the hosts on the LAN would be configured with the virtual IP address of group 1 and the remaining hosts would be configured with the virtual IP address of group 2. See the Example: Multiple HSRP for Load Balancing section for a diagram and configuration example.

SUMMARY STEPS

1.    enable

2.    configure terminal

3.    interface type number

4.    ip address ip-address mask [secondary]

5.    standby [group-number] priority priority

6.    standby [group-number] preempt [delay {minimum | reload | sync} delay]

7.    standby [group-number] ip [ip-address] secondary]

8.    On the same device, repeat Steps 5 through 7 to configure the device attributes for different standby groups.

9.    exit

10.    Repeat Steps 3 through 9 on another device.

DETAILED STEPS

Command or Action

Purpose

Step 1

enable

Example:

Device> enable

Enables privileged EXEC mode.

- Enter your password if prompted.

Step 2

configure terminal

Example:

Device# configure terminal

Enters global configuration mode.

Step 3

interface type number

Example:

Device(config)# interface GigabitEthernet 0/0/0

Configures an interface type and enters interface configuration mode.

Step 4

ip address ip-address mask [secondary]

Example:

Device(config-if)# ip address 10.0.0.1 255.255.255.0

Specifies a primary or secondary IP address for an interface.

Step 5

standby [group-number] priority priority

Example:

Device(config-if)# standby 1 priority 110

Configures HSRP priority.

Step 6

standby [group-number] preempt [delay {minimum | reload | sync} delay]

Example:

Device(config-if)# standby 1 preempt

Configures HSRP preemption.

Step 7

standby [group-number] ip [ip-address] secondary]

Example:

Device(config-if)# standby 1 ip 10.0.0.3

Activates HSRP.

Step 8

On the same device, repeat Steps 5 through 7 to configure the device attributes for different standby groups.

For example, Device A can be configured as an active device for group 1 and be configured as an active or standby device for another HSRP group with different priority and preemption values.

Step 9

exit

Example:

Device(config-if)# exit

Exits to global configuration mode.

Step 10

Repeat Steps 3 through 9 on another device.

Configures multiple HSRP and enables load balancing on another device.

Improving CPU and Network Performance with HSRP Multiple Group Optimization

Perform this task to configure multiple HSRP client groups.

The standby follow command configures an HSRP group to become a slave of another HSRP group.

HSRP client groups follow the master HSRP with a slight, random delay so that all client groups do not change at the same time.

Use the standby mac-refresh seconds command to directly change the HSRP client group refresh interval. The default interval is 10 seconds and can be configured to as much as 255 seconds.

Note

- Client or slave groups must be on the same physical interface as the master group.

- A client group takes its state from the group it is following. Therefore, the client group does not use its timer, priority, or preemption settings. A warning is displayed if these settings are configured on a client group:

Device(config-if)# standby 1 priority 110
%Warning: This setting has no effect while following another group.
Device(config-if)# standby 1 timers 5 15
% Warning: This setting has no effect while following another group.
Device(config-if)# standby 1 preempt delay minimum 300
% Warning: This setting has no effect while following another group.

Before You Begin

Configure the HSRP master group using the steps in the Configuring Multiple HSRP Groups for Load Balancing section.

SUMMARY STEPS

1.    enable

2.    configure terminal

3.    interface type number

4.    ip address ip-address mask [secondary]

5.    standby mac-refresh seconds

6.    standby group-number follow group-name

7.    exit

8.    Repeat Steps 3 through 6 to configure additional HSRP client groups.

DETAILED STEPS

Command or Action

Purpose

Step 1

enable

Example:

Device> enable

Enables privileged EXEC mode.

- Enter your password if prompted.

Step 2

configure terminal

Example:

Device# configure terminal

Enters global configuration mode.

Step 3

interface type number

Example:

Device(config)# interface GigabitEthernet 0/0/0

Configures an interface type and enters interface configuration mode.

Step 4

ip address ip-address mask [secondary]

Example:

Device(config-if)# ip address 10.0.0.1 255.255.255.0

Specifies a primary or secondary IP address for an interface.

Step 5

standby mac-refresh seconds

Example:

Device(config-if)# standby mac-refresh 30

Configures the HSRP client group refresh interval.

Step 6

standby group-number follow group-name

Example:

Device(config-if)# standby 1 follow HSRP1

Configures an HSRP group as a client group.

Step 7

exit

Example:

Device(config-if)# exit

Exits to global configuration mode.

Step 8

Repeat Steps 3 through 6 to configure additional HSRP client groups.

Configures multiple HSRP client groups.

Configuration Examples for FHRP - Multiple Group Optimization

- Example: Configuring Multiple HSRP Groups for Load Balancing

- Example: Improving CPU and Network Performance with HSRP Multiple Group Optimization

Example: Configuring Multiple HSRP Groups for Load Balancing

You can use HSRP or multiple HSRP groups when you configure load sharing. In the figure below, half of the clients are configured for Router A, and half of the clients are configured for Router B. Together, the configuration for Routers A and B establish two Hot Standby groups. For group 1, Router A is the default active router because it has the assigned highest priority, and Router B is the standby router. For group 2, Router B is the default active router because it has the assigned highest priority, and Router A is the standby router. During normal operation, the two routers share the IP traffic load. When either router becomes unavailable, the other router becomes active and assumes the packet-transfer functions of the router that is unavailable. The standby preempt interface configuration command is necessary so that if a router goes down and then comes back up, preemption occurs and restores load sharing.

HSRP Load Sharing Example

The following example shows Router A configured as the active router for group 1 with a priority of 110 and Router B configured as the active router for group 2 with a priority of 110. The default priority level is 100. Group 1 uses a virtual IP address of 10.0.0.3 and Group 2 uses a virtual IP address of 10.0.0.4.

Router A Configuration

Router(config)# hostname RouterA
!
Router(config)# interface GigabitEthernet 0/0/0
Router(config-if)# ip address 10.0.0.1 255.255.255.0
Router(config-if)# standby 1 priority 110
Router(config-if)# standby 1 preempt
Router(config-if)# standby 1 ip 10.0.0.3
Router(config-if)# standby 2 preempt
Router(config-if)# standby 2 ip 10.0.0.4

Router B Configuration

Router(config)# hostname RouterB
!
Router(config)# interface GigabitEthernet 0/0/0
Router(config-if)# ip address 10.0.0.2 255.255.255.0
Router(config-if)# standby 1 preempt
Router(config-if)# standby 1 ip 10.0.0.3
Router(config-if)# standby 2 priority 110
Router(config-if)# standby 2 preempt
Router(config-if)# standby 2 ip 10.0.0.4

Example: Improving CPU and Network Performance with HSRP Multiple Group Optimization

The following example shows how to configure an HSRP client and master group:

Device(config)# interface GigabitEthernet 0/0/0
Device(config-if)# no shutdown
Device(config-if)# standby mac-refresh 30
! Client Hello message interval
!
Device(config)# interface GigabitEthernet 0/0/1
Device(config-if)# no shutdown
Device(config-if)# ip vrf forwarding VRF2
Device(config-if)# ip address 10.0.0.100 255.255.0.0
Device(config-if)# standby 1 ip 10.0.0.254
Device(config-if)# standby 1 priority 110
Device(config-if)# standby 1 preempt
Device(config-if)# standby 1 name HSRP1
!Server group
!
Device(config)# interface GigabitEthernet 0/0/2
Device(config-if)# no shutdown
Device(config-if)# ip vrf forwarding VRF3
Device(config-if)# ip address 10.0.0.100 255.255.0.0
Device(config-if)# standby 2 ip 10.0.0.254
Device(config-if)# standby 2 follow HSRP1
! Client group
!
Device(config)# interface GigabitEthernet 0/0/3
Device(config-if)# no shutdown
Device(config-if)# ip vrf forwarding VRF4
Device(config-if)# ip address 10.0.0.100 255.255.0.0
Device(config-if)# standby 2 ip 10.0.0.254
Device(config-if)# standby 2 follow HSRP1
! Client group

Additional References

Related Documents

Related Topic

Document Title

Cisco IOS commands

Cisco IOS Master Commands List, All Releases

HSRP commands: complete command syntax, command mode, command history, defaults, usage guidelines, and examples

Cisco IOS First Hop redundancy Protocols Command Reference

HSRP for IPv6

“HSRP for IPv6” module

Troubleshooting HSRP

Hot Standby Router Protocol: Frequently Asked Questions

Standards

Standards

Title

No new or modified standards are supported by this feature, and support for existing standards has not been modified by this feature.

--

MIBs

MIBs

MIBs Link

CISCO-HSRP-MIB CISCO-HSRP-EXT-MIB

To locate and download MIBs for selected platforms, Cisco software releases, and feature sets, use Cisco MIB Locator found at the following URL:

Click Here

RFCs

RFCs

Title

RFC 792

Internet Control Message Protocol

RFC 1828

IP Authentication Using Keyed MD5

RFC 2281

Cisco Hot Standby Router Protocol

Technical Assistance

Description

Link

The Cisco Support and Documentation website provides online resources to download documentation, software, and tools. Use these resources to install and configure the software and to troubleshoot and resolve technical issues with Cisco products and technologies. Access to most tools on the Cisco Support and Documentation website requires a Cisco.com user ID and password.

Click Here

Feature Information for FHRP - HSRP Multiple Group Optimization

The following table provides release information about the feature or features described in this module. This table lists only the software release that introduced support for a given feature in a given software release train. Unless noted otherwise, subsequent releases of that software release train also support that feature.

Use Cisco Feature Navigator to find information about platform support and Cisco software image support. To access Cisco Feature Navigator, go to Click Here . An account on Cisco.com is not required.

Feature Information for FHRP—HSRP Multiple Group Optimization

Feature Name

Releases

Feature Information

FHRP—HSRP Multiple Group Optimization

12.4(6)T

12.2(33)SRB

12.2(33)SXI

12.2(50)SY

15.0(1)S

15.0(1)SY

Cisco IOS XE Release 2.1

FHRP—HSRP Multiple Group Optimization feature improves the negotiation and maintenance of multiple HSRP groups configured on a subinterface. Only one HSRP group is required on a physical interface for the purposes of electing active and standby devices. This group is known as the master group. Other HSRP groups may be created on each subinterface and linked to the master group via the group name. These linked HSRP groups are known as client or slave groups.

The following commands were introduced or modified by this feature: standby follow, show standby.

Chapter 10. Configuring IRDP

The ICMP Router Discovery Protocol (IRDP) allows IPv4 hosts to locate routers that provide IPv4 connectivity to other (nonlocal) IP networks. For a complete description of the IPv4 addressing commands in this module, refer to the Cisco IOS IP Application Services Command Reference. To locate documentation of other commands that appear in this module, use the command reference master index or search online.

This module explains the concepts related to IRDP and describes how to configure IRDP in a network.

- Finding Feature Information

- Information About IRDP

- How to Configure IRDP

- Configuration Examples for IRDP

- Additional References

- Feature Information for IRDP

Finding Feature Information

Your software release may not support all the features documented in this module. For the latest caveats and feature information, see Bug Search Tool and the release notes for your platform and software release. To find information about the features documented in this module, and to see a list of the releases in which each feature is supported, see the feature information table.

Use Cisco Feature Navigator to find information about platform support and Cisco software image support. To access Cisco Feature Navigator, go to Click Here . An account on Cisco.com is not required.

Information About IRDP

- IRDP Overview

IRDP Overview

ICMP Router Discovery Protocol (IRDP) allows hosts to locate routers that can be used as a gateway to reach IP-based devices on other networks. When the device running IRDP operates as a router, router discovery packets are generated. When the device running IRDP operates as a host, router discovery packets are received. The Cisco IRDP implementation fully conforms to the router discovery protocol outlined in RFC 1256 ( Click Here ).

How to Configure IRDP

- Configuring IRDP

Configuring IRDP

SUMMARY STEPS

1.    enable

2.    configure terminal

3.    no ip routing

4.    ip gdp irdp [multicast]

5.    interface type number

6.    no shutdown

7.    ip address ip-address mask

8.    ip irdp

9.    ip irdp multicast

10.    ip irdp holdtime seconds

11.    ip irdp maxadvertinterval seconds

12.    ip irdp minadvertinterval seconds

13.    ip irdp preference number

14.    ip irdp address address number

15.    end

DETAILED STEPS

Command or Action

Purpose

Step 1

enable

Example:

Router> enable

Enables privileged EXEC mode.

- Enter your password if prompted.

Step 2

configure terminal

Example:

Router# configure terminal

Enters global configuration mode.

Step 3

no ip routing

Example:

Router(config)# no ip routing

Disables IP routing

Step 4

ip gdp irdp [multicast]

Example:

Router(config)# ip gdp irdp

Configures a gateway to discover routers that transmit IRDP router updates.

Step 5

interface type number

Example:

Router(config)# interface fastethernet 0/0

Specifies an interface and enters interface configuration mode.

Step 6

no shutdown

Example:

Router(config-if)# no shutdown

Activates (enables) the interface.

Step 7

ip address ip-address mask

Example:

Router(config-if)# ip address 172.16.16.1 255.255.240.0

Configures an IP address on the interface.

Step 8

ip irdp

Example:

Router(config-if)# ip irdp

Enables IRDP on the interface

Step 9

ip irdp multicast

Example:

Router(config-if)# ip irdp multicast

(Optional) Sends IRDP advertisements to the all-systems multicast address (224.0.0.1) on a specified interface.

Step 10

ip irdp holdtime seconds

Example:

Router(config-if)# ip irdp holdtime 120

(Optional) Sets the IRDP period for which advertisements are valid.

Step 11

ip irdp maxadvertinterval seconds

Example:

Router(config-if)# ip irdp maxadvertinterval 60

(Optional) Sets the IRDP maximum interval between advertisements.

Step 12

ip irdp minadvertinterval seconds

Example:

Router(config-if)# ip irdp minadvertinterval 10

(Optional) Sets the IRDP minimum interval between advertisements.

Step 13

ip irdp preference number

Example:

Router(config-if)# ip irdp preference 900

(Optional) Sets the IRDP preference level of the device.

Step 14

ip irdp address address number

Example:

Router(config-if)# ip irdp address 192.168.10.2 90

(Optional) Specifies an IRDP address and preference to proxy-advertise.

Step 15

end

Example:

Router(config-if)# end

Exits the current configuration mode and returns to privileged EXEC mode.

Configuration Examples for IRDP

- Example: Configuring IRDP

Example: Configuring IRDP

The following example shows how to configure IRDP on a router:

Router(config)# no ip routing
Router(config)# ip gdp irdp
Router(config)# interface fastethernet 0/1
Router(config-if)# no shutdown
Router(config-if)# ip address 172.16.10.1 255.255.255.0
Router(config-if)# ip irdp
Router(config-if)# ip irdp multicast
Router(config-if)# ip irdp holdtime 120
Router(config-if)# ip irdp maxadvertinterval 60
Router(config-if)# ip irdp minadvertinterval 10
Router(config-if)# ip irdp preference 900
Router(config-if)# ip irdp address 192.168.10.2 90

Additional References

Related Documents

Related Topic

Document Title

Cisco IOS commands

Cisco IOS Master Commands List, All Releases

IP application services commands

Cisco IOS IP Application Services Command Reference

Standards and RFCs

Standard

Title

RFC 1256

ICMP Router Discovery Messages

Technical Assistance

Description

Link

The Cisco Support and Documentation website provides online resources to download documentation, software, and tools. Use these resources to install and configure the software and to troubleshoot and resolve technical issues with Cisco products and technologies. Access to most tools on the Cisco Support and Documentation website requires a Cisco.com user ID and password.

Click Here

Feature Information for IRDP

The following table provides release information about the feature or features described in this module. This table lists only the software release that introduced support for a given feature in a given software release train. Unless noted otherwise, subsequent releases of that software release train also support that feature.

Use Cisco Feature Navigator to find information about platform support and Cisco software image support. To access Cisco Feature Navigator, go to Click Here . An account on Cisco.com is not required.

Feature Information for IRDP

Feature Name

Releases

Feature Information

ICMP Router Discovery Protocol

10.0

12.2(33)SRA

The ICMP Router Discovery Protocol (IRDP) allows IPv4 hosts to locate routers that provide IPv4 connectivity to other (nonlocal) IP networks.

The following command was introduced or modified: ip irdp.

Chapter 11. Configuring VRRP

The Virtual Router Redundancy Protocol (VRRP) is an election protocol that dynamically assigns responsibility for one or more virtual routers to the VRRP routers on a LAN, allowing several routers on a multiaccess link to utilize the same virtual IP address. A VRRP router is configured to run the VRRP protocol in conjunction with one or more other routers attached to a LAN. In a VRRP configuration, one router is elected as the virtual router master, with the other routers acting as backups in case the virtual router master fails.

This module explains the concepts related to VRRP and describes how to configure VRRP in a network.

- Finding Feature Information

- Restrictions for VRRP

- Information About VRRP

- How to Configure VRRP

- Configuration Examples for VRRP

- Additional References for Configuring VRRP

- Feature Information for VRRP

- Glossary

Finding Feature Information

Your software release may not support all the features documented in this module. For the latest caveats and feature information, see Bug Search Tool and the release notes for your platform and software release. To find information about the features documented in this module, and to see a list of the releases in which each feature is supported, see the feature information table.

Use Cisco Feature Navigator to find information about platform support and Cisco software image support. To access Cisco Feature Navigator, go to Click Here . An account on Cisco.com is not required.

Restrictions for VRRP

- VRRP is designed for use over multiaccess, multicast, or broadcast capable Ethernet LANs. VRRP is not intended as a replacement for existing dynamic protocols.

- VRRP is supported on Ethernet, Fast Ethernet, Bridge Group Virtual Interface (BVI), and Gigabit Ethernet interfaces, and on Multiprotocol Label Switching (MPLS) Virtual Private Networks (VPNs), VRF-aware MPLS VPNs, and VLANs.

- Because of the forwarding delay that is associated with the initialization of a BVI interface, you must configure the VRRP advertise timer to a value equal to or greater than the forwarding delay on the BVI interface. This setting prevents a VRRP router on a recently initialized BVI interface from unconditionally taking over the master role. Use the bridge forward-time command to set the forwarding delay on the BVI interface. Use the vrrp timers advertise command to set the VRRP advertisement timer.

Information About VRRP

- VRRP Operation

- VRRP Benefits

- Multiple Virtual Router Support

- VRRP Router Priority and Preemption

- VRRP Advertisements

- VRRP Object Tracking

- How Object Tracking Affects the Priority of a VRRP Router

- VRRP Authentication

- In Service Software Upgrade--VRRP

- VRRP Support for Stateful Switchover

VRRP Operation

There are several ways a LAN client can determine which router should be the first hop to a particular remote destination. The client can use a dynamic process or static configuration. Examples of dynamic router discovery are as follows:

- Proxy ARP—The client uses Address Resolution Protocol (ARP) to get the destination it wants to reach, and a router will respond to the ARP request with its own MAC address.

- Routing protocol—The client listens to dynamic routing protocol updates (for example, from Routing Information Protocol [RIP]) and forms its own routing table.

- ICMP Router Discovery Protocol (IRDP) client—The client runs an Internet Control Message Protocol (ICMP) router discovery client.

The drawback to dynamic discovery protocols is that they incur some configuration and processing overhead on the LAN client. Also, in the event of a router failure, the process of switching to another router can be slow.

An alternative to dynamic discovery protocols is to statically configure a default router on the client. This approach simplifies client configuration and processing, but creates a single point of failure. If the default gateway fails, the LAN client is limited to communicating only on the local IP network segment and is cut off from the rest of the network.

VRRP can solve the static configuration problem. VRRP enables a group of routers to form a single virtual router. The LAN clients can then be configured with the virtual router as their default gateway. The virtual router, representing a group of routers, is also known as a VRRP group.

VRRP is supported on Ethernet, Fast Ethernet, BVI, and Gigabit Ethernet interfaces, and on MPLS VPNs, VRF-aware MPLS VPNs, and VLANs.

The figure below shows a LAN topology in which VRRP is configured. In this example, Routers A, B, and C are VRRP routers (routers running VRRP) that comprise a virtual router. The IP address of the virtual router is the same as that configured for the Ethernet interface of Router A (10.0.0.1).

Basic VRRP Topology

Because the virtual router uses the IP address of the physical Ethernet interface of Router A, Router A assumes the role of the virtual router master and is also known as the IP address owner. As the virtual router master, Router A controls the IP address of the virtual router and is responsible for forwarding packets sent to this IP address. Clients 1 through 3 are configured with the default gateway IP address of 10.0.0.1.

Routers B and C function as virtual router backups. If the virtual router master fails, the router configured with the higher priority will become the virtual router master and provide uninterrupted service for the LAN hosts. When Router A recovers, it becomes the virtual router master again. For more detail on the roles that VRRP routers play and what happens if the virtual router master fails, see the VRRP Router Priority and Preemption section.

The figure below shows a LAN topology in which VRRP is configured so that Routers A and B share the traffic to and from clients 1 through 4 and that Routers A and B act as virtual router backups to each other if either router fails.

Load Sharing and Redundancy VRRP Topology

In this topology, two virtual routers are configured. (For more information, see the Multiple Virtual Router Support section.) For virtual router 1, Router A is the owner of IP address 10.0.0.1 and virtual router master, and Router B is the virtual router backup to Router A. Clients 1 and 2 are configured with the default gateway IP address of 10.0.0.1.

For virtual router 2, Router B is the owner of IP address 10.0.0.2 and virtual router master, and Router A is the virtual router backup to Router B. Clients 3 and 4 are configured with the default gateway IP address of 10.0.0.2.

VRRP Benefits

Redundancy

VRRP enables you to configure multiple routers as the default gateway router, which reduces the possibility of a single point of failure in a network.

Load Sharing

You can configure VRRP in such a way that traffic to and from LAN clients can be shared by multiple routers, thereby sharing the traffic load more equitably among available routers.

Multiple Virtual Routers

Multiple IP Addresses

The virtual router can manage multiple IP addresses, including secondary IP addresses. Therefore, if you have multiple subnets configured on an Ethernet interface, you can configure VRRP on each subnet.

Preemption

The redundancy scheme of VRRP enables you to preempt a virtual router backup that has taken over for a failing virtual router master with a higher priority virtual router backup that has become available.

Authentication

VRRP message digest 5 (MD5) algorithm authentication protects against VRRP-spoofing software and uses the industry-standard MD5 algorithm for improved reliability and security.

Advertisement Protocol

VRRP uses a dedicated Internet Assigned Numbers Authority (IANA) standard multicast address (224.0.0.18) for VRRP advertisements. This addressing scheme minimizes the number of routers that must service the multicasts and allows test equipment to accurately identify VRRP packets on a segment. The IANA assigned VRRP the IP protocol number 112.

VRRP Object Tracking

VRRP object tracking provides a way to ensure the best VRRP router is the virtual router master for the group by altering VRRP priorities to the status of tracked objects such as the interface or IP route states.

Multiple Virtual Router Support

- Router processing capability

- Router memory capability

- Router interface support of multiple MAC addresses

In a topology where multiple virtual routers are configured on a router interface, the interface can act as a master for one virtual router and as a backup for one or more virtual routers.

VRRP Router Priority and Preemption

An important aspect of the VRRP redundancy scheme is VRRP router priority. Priority determines the role that each VRRP router plays and what happens if the virtual router master fails.

If a VRRP router owns the IP address of the virtual router and the IP address of the physical interface, this router will function as a virtual router master.

Priority also determines if a VRRP router functions as a virtual router backup and the order of ascendancy to becoming a virtual router master if the virtual router master fails. You can configure the priority of each virtual router backup with a value of 1 through 254 using the vrrp priority command.

For example, if Router A, the virtual router master in a LAN topology, fails, an election process takes place to determine if virtual router backups B or C should take over. If Routers B and C are configured with the priorities of 101 and 100, respectively, Router B is elected to become virtual router master because it has the higher priority. If Routers B and C are both configured with the priority of 100, the virtual router backup with the higher IP address is elected to become the virtual router master.

By default, a preemptive scheme is enabled whereby a higher priority virtual router backup that becomes available takes over for the virtual router backup that was elected to become virtual router master. You can disable this preemptive scheme using the no vrrp preempt command. If preemption is disabled, the virtual router backup that is elected to become virtual router master remains the master until the original virtual router master recovers and becomes master again.

VRRP Advertisements

The virtual router master sends VRRP advertisements to other VRRP routers in the same group. The advertisements communicate the priority and state of the virtual router master. The VRRP advertisements are encapsulated in IP packets and sent to the IP Version 4 multicast address assigned to the VRRP group. The advertisements are sent every second by default; the interval is configurable.

Although the VRRP protocol as per RFC 3768 does not support millisecond timers, Cisco routers allow you to configure millisecond timers. You need to manually configure the millisecond timer values on both the primary and the backup routers. The master advertisement value displayed in the show vrrp command output on the backup routers is always 1 second because the packets on the backup routers do not accept millisecond values.

You must use millisecond timers where absolutely necessary and with careful consideration and testing. Millisecond values work only under favorable circumstances, and you must be aware that the use of the millisecond timer values restricts VRRP operation to Cisco devices only.

VRRP Object Tracking

Object tracking is an independent process that manages creating, monitoring, and removing tracked objects such as the state of the line protocol of an interface. Clients such as the Hot Standby Router Protocol (HSRP), Gateway Load Balancing Protocol (GLBP), and VRRP register their interest with specific tracked objects and act when the state of an object changes.

Each tracked object is identified by a unique number that is specified on the tracking CLI. Client processes such as VRRP use this number to track a specific object.

The tracking process periodically polls the tracked objects and notes any change of value. The changes in the tracked object are communicated to interested client processes, either immediately or after a specified delay. The object values are reported as either up or down.

VRRP object tracking gives VRRP access to all the objects available through the tracking process. The tracking process allows you to track individual objects such as a the state of an interface line protocol, state of an IP route, or the reachability of a route.

VRRP provides an interface to the tracking process. Each VRRP group can track multiple objects that may affect the priority of the VRRP device. You specify the object number to be tracked and VRRP is notified of any change to the object. VRRP increments (or decrements) the priority of the virtual device based on the state of the object being tracked.

How Object Tracking Affects the Priority of a VRRP Router

The priority of a device can change dynamically if it has been configured for object tracking and the object that is being tracked goes down. The tracking process periodically polls the tracked objects and notes any change of value. The changes in the tracked object are communicated to VRRP, either immediately or after a specified delay. The object values are reported as either up or down. Examples of objects that can be tracked are the line protocol state of an interface or the reachability of an IP route. If the specified object goes down, the VRRP priority is reduced. The VRRP router with the higher priority can now become the virtual router master if it has the vrrp preempt command configured. See the VRRP Object Tracking section for more information on object tracking.

VRRP Authentication

VRRP ignores unauthenticated VRRP protocol messages. The default authentication type is text authentication.

You can configure VRRP text authentication, authentication using a simple MD5 key string, or MD5 key chains for authentication.

MD5 authentication provides greater security than the alternative plain text authentication scheme. MD5 authentication allows each VRRP group member to use a secret key to generate a keyed MD5 hash of the packet that is part of the outgoing packet. A keyed hash of an incoming packet is generated and if the generated hash does not match the hash within the incoming packet, the packet is ignored.

The key for the MD5 hash can either be given directly in the configuration using a key string or supplied indirectly through a key chain.

A router will ignore incoming VRRP packets from routers that do not have the same authentication configuration for a VRRP group. VRRP has three authentication schemes:

- No authentication

- Plain text authentication

- MD5 authentication

VRRP packets will be rejected in any of the following cases:

- The authentication schemes differ on the router and in the incoming packet.

- MD5 digests differ on the router and in the incoming packet.

- Text authentication strings differ on the router and in the incoming packet.

In Service Software Upgrade--VRRP

VRRP supports In Service Software Upgrade (ISSU). In Service Software Upgrade (ISSU) allows a high-availability (HA) system to run in stateful switchover (SSO) mode even when different versions of Cisco IOS software are running on the active and standby Route Processors (RPs) or line cards.

ISSU provides the ability to upgrade or downgrade from one supported Cisco IOSrelease to another while continuing to forward packets and maintain sessions, thereby reducing planned outage time. The ability to upgrade or downgrade is achieved by running different software versions on the active RP and standby RP for a short period of time to maintain state information between RPs. This feature allows the system to switch over to a secondary RP running upgraded (or downgraded) software and continue forwarding packets without session loss and with minimal or no packet loss. This feature is enabled by default.

For detailed information about ISSU, see theCisco IOS In Service Software Upgrade Process document in the Cisco IOS High Availability Configuration Guide.

VRRP Support for Stateful Switchover

With the introduction of the VRRP Support for Stateful Switchover feature, VRRP is SSO aware. VRRP can detect when a router is failing over to the secondary RP and continue in its current group state.

SSO functions in networking devices (usually edge devices) that support dual Route Processors (RPs). SSO provides RP redundancy by establishing one of the RPs as the active processor and the other RP as the standby processor. SSO also synchronizes critical state information between the RPs so that network state information is dynamically maintained between RPs.

Prior to being SSO aware, if VRRP was deployed on a router with redundant RPs, a switchover of roles between the active RP and the standby RP would result in the router relinquishing its activity as a VRRP group member and then rejoining the group as if it had been reloaded. The SSO--VRRP feature enables VRRP to continue its activities as a group member during a switchover. VRRP state information between redundant RPs is maintained so that the standby RP can continue the router’s activities within the VRRP during and after a switchover.

This feature is enabled by default. To disable this feature, use the no vrrp sso command in global configuration mode.

For more information, see the Stateful Switchover document.

How to Configure VRRP

- Customizing VRRP

- Enabling VRRP

- Disabling a VRRP Group on an Interface

- Configuring VRRP Object Tracking

- Configuring VRRP MD5 Authentication Using a Key String

- Configuring VRRP MD5 Authentication Using a Key Chain

- Verifying the VRRP MD5 Authentication Configuration

- Configuring VRRP Text Authentication

- Enabling the Router to Send SNMP VRRP Notifications

Customizing VRRP

Customizing the behavior of VRRP is optional. Be aware that as soon as you enable a VRRP group, that group is operating. It is possible that if you first enable a VRRP group before customizing VRRP, the router could take over control of the group and become the virtual router master before you have finished customizing the feature. Therefore, if you plan to customize VRRP, it is a good idea to do so before enabling VRRP.

SUMMARY STEPS

1.    enable

2.    configure terminal

3.    interface type number

4.    ip address ip-address mask

5.    vrrp group description text

6.    vrrp group priority level

7.    vrrp group preempt [delay minimum seconds]

8.    vrrp group timers learn

9.    exit

10.    no vrrp sso

DETAILED STEPS

Command or Action

Purpose

Step 1

enable

Example:

Router> enable

Enables privileged EXEC mode.

- Enter your password if prompted.

Step 2

configure terminal

Example:

Router# configure terminal

Enters global configuration mode.

Step 3

interface type number

Example:

Router(config)# interface GigabitEthernet 0/0/0

Enters interface configuration mode.

Step 4

ip address ip-address mask

Example:

Router(config-if)# ip address 172.16.6.5 255.255.255.0

Configures an IP address for an interface.

Step 5

vrrp group description text

Example:

Router(config-if)# vrrp 10 description working-group

Assigns a text description to the VRRP group.

Step 6

vrrp group priority level

Example:

Router(config-if)# vrrp 10 priority 110

Sets the priority level of the router within a VRRP group.

- The default priority is 100.

Step 7

vrrp group preempt [delay minimum seconds]

Example:

Router(config-if)# vrrp 10 preempt delay minimum 380

Configures the router to take over as virtual router master for a VRRP group if it has a higher priority than the current virtual router master.

- The default delay period is 0 seconds.

- The router that is IP address owner will preempt, regardless of the setting of this command.

Step 8

vrrp group timers learn

Example:

Router(config-if)# vrrp 10 timers learn

Configures the router, when it is acting as virtual router backup for a VRRP group, to learn the advertisement interval used by the virtual router master.

Step 9

exit

Example:

Router(config-if)# exit

Exits interface configuration mode.

Step 10

no vrrp sso

Example:

Router(config)# no vrrp sso

(Optional) Disables VRRP support of SSO.

- VRRP support of SSO is enabled by default.

Enabling VRRP

SUMMARY STEPS

1.    enable

2.    configure terminal

3.    interface type number

4.    ip address ip-address mask

5.    vrrp group ip ip-address [secondary]

6.    end

7.    show vrrp [brief] | group]

8.    show vrrp interface type number [brief]

DETAILED STEPS

Command or Action

Purpose

Step 1

enable

Example:

Router> enable

Enables privileged EXEC mode.

- Enter your password if prompted.

Step 2

configure terminal

Example:

Router# configure terminal

Enters global configuration mode.

Step 3

interface type number

Example:

Router(config)# interface GigabitEthernet 0/0/0

Enters interface configuration mode.

Step 4

ip address ip-address mask

Example:

Router(config-if)# ip address 172.16.6.5 255.255.255.0

Configures an IP address for an interface.

Step 5

vrrp group ip ip-address [secondary]

Example:

Router(config-if)# vrrp 10 ip 172.16.6.1

Enables VRRP on an interface.

- After you identify a primary IP address, you can use the vrrp ip command again with the secondary keyword to indicate additional IP addresses supported by this group.

Note:
All routers in the VRRP group must be configured with the same primary address and a matching list of secondary addresses for the virtual router. If different primary or secondary addresses are configured, the routers in the VRRP group will not communicate with each other and any misconfigured router will change its state to master.

Step 6

end

Example:

Router(config-if)# end

Returns to privileged EXEC mode.

Step 7

show vrrp [brief] | group]

Example:

Router# show vrrp 10

(Optional) Displays a brief or detailed status of one or all VRRP groups on the router.

Step 8

show vrrp interface type number [brief]

Example:

Router# show vrrp interface GigabitEthernet 0/0/0

(Optional) Displays the VRRP groups and their status on a specified interface.

Disabling a VRRP Group on an Interface

Disabling a VRRP group on an interface allows the protocol to be disabled, but the configuration to be retained. This ability was added with the introduction of the VRRP MIB, RFC 2787, Definitions of Managed Objects for the Virtual Router Redundancy Protocol .

You can use a Simple Network Management Protocol (SNMP) management tool to enable or disable VRRP on an interface. Because of the SNMP management capability, the vrrp shutdown command was introduced to represent a method via the command line interface (CLI) for VRRP to show the state that had been configured using SNMP.

When the show running-config command is entered, you can see immediately if the VRRP group has been configured and set to enabled or disabled. This is the same functionality that is enabled within the MIB.

The no form of the command enables the same operation that is performed within the MIB. If the vrrp shutdown command is specified using the SNMP interface, then entering the no vrrp shutdown command reenables the VRRP group.

SUMMARY STEPS

1.    enable

2.    configure terminal

3.    interface type number

4.    ip address ip-address mask

5.    vrrp group shutdown

DETAILED STEPS

Command or Action

Purpose

Step 1

enable

Example:

Router> enable

Enables privileged EXEC mode.

- Enter your password if prompted.

Step 2

configure terminal

Example:

Router# configure terminal

Enters global configuration mode.

Step 3

interface type number

Example:

Router(config)# interface GigabitEthernet0/0/0

Enters interface configuration mode.

Step 4

ip address ip-address mask

Example:

Router(config-if)# ip address 172.16.6.5 255.255.255.0

Configures an IP address for an interface.

Step 5

vrrp group shutdown

Example:

Router(config-if)# vrrp 10 shutdown

Disables the VRRP group on an interface.

- The command is now visible on the router.

Note:
You can have one VRRP group disabled, while retaining its configuration, and a different VRRP group enabled.

Configuring VRRP Object Tracking

Note

If a VRRP group is the IP address owner, its priority is fixed at 255 and cannot be reduced through object tracking.

SUMMARY STEPS

1.    enable

2.    configure terminal

3.    track object-number interface type number {line-protocol | ip routing}

4.    interface type number

5.    vrrp group ip ip-address

6.    vrrp group priority level

7.    vrrp group track object-number [decrement priority]

8.    end

9.    show track [object-number]

DETAILED STEPS

Command or Action

Purpose

Step 1

enable

Example:

Router> enable

Enables privileged EXEC mode.

- Enter your password if prompted.

Step 2

configure terminal

Example:

Router# configure terminal

Enters global configuration mode.

Step 3

track object-number interface type number {line-protocol | ip routing}

Example:

Router(config)# track 2 interface serial 6 line-protocol

Configures an interface to be tracked where changes in the state of the interface affect the priority of a VRRP group.

- This command configures the interface and corresponding object number to be used with the vrrp track command.

- The line-protocol keyword tracks whether the interface is up. The ip routing keyword also checks that IP routing is enabled and active on the interface.

- You can also use the track ip route command to track the reachability of an IP route or a metric type object.

Step 4

interface type number

Example:

Router(config)# interface Ethernet 2

Enters interface configuration mode.

Step 5

vrrp group ip ip-address

Example:

Router(config-if)# vrrp 1 ip 10.0.1.20

Enables VRRP on an interface and identifies the IP address of the virtual router.

Step 6

vrrp group priority level

Example:

Router(config-if)# vrrp 1 priority 120

Sets the priority level of the router within a VRRP group.

Step 7

vrrp group track object-number [decrement priority]

Example:

Router(config-if)# vrrp 1 track 2 decrement 15

Configures VRRP to track an object.

Step 8

end

Example:

Router(config-if)# end

Returns to privileged EXEC mode.

Step 9

show track [object-number]

Example:

Router# show track 1

Displays tracking information.

Configuring VRRP MD5 Authentication Using a Key String

Note

Interoperability with vendors that may have implemented the RFC 2338 method is not enabled.

Text authentication cannot be combined with MD5 authentication for a VRRP group at any one time. When MD5 authentication is configured, the text authentication field in VRRP hello messages is set to all zeroes on transmit and ignored on receipt, provided the receiving router also has MD5 authentication enabled.

SUMMARY STEPS

1.    enable

2.    configure terminal

3.    interface type number

4.    ip address ip-address mask [secondary]

5.    vrrp group priority priority

6.    vrrp group authentication md5 key-string [0 | 7] key-string [timeout seconds]

7.    vrrp group ip [ip-address[secondary]]

8.    Repeat Steps 1 through 7 on each router that will communicate.

9.    end

DETAILED STEPS

Command or Action

Purpose

Step 1

enable

Example:

Router> enable

Enables privileged EXEC mode.

- Enter your password if prompted.

Step 2

configure terminal

Example:

Router# configure terminal

Enters global configuration mode.

Step 3

interface type number

Example:

Router(config)# interface Ethernet0/1

Configures an interface type and enters interface configuration mode.

Step 4

ip address ip-address mask [secondary]

Example:

Router(config-if)# ip address 10.0.0.1 255.255.255.0

Specifies a primary or secondary IP address for an interface.

Step 5

vrrp group priority priority

Example:

Router(config-if)# vrrp 1 priority 110

Configures VRRP priority.

Step 6

vrrp group authentication md5 key-string [0 | 7] key-string [timeout seconds]

Example:

Router(config-if)# vrrp 1 authentication md5 key-string d00b4r987654321a timeout 30

Configures an authentication string for VRRP MD5 authentication.

- The keyargument can be up to 64 characters in length and it is recommended that at least 16 characters be used.

- No prefix to the key argument or specifying 0 means the key will be unencrypted.

- Specifying 7 means the key will be encrypted. The key-string authentication key will automatically be encrypted if the service password-encryption global configuration command is enabled.

- The timeout value is the period of time that the old key string will be accepted to allow configuration of all routers in a group with a new key.

Note:
All routers within the VRRP group must be configured with the same authentication string. If the same authentication string is not configured, the routers in the VRRP group will not communicate with each other and any misconfigured router will change its state to master.

Step 7

vrrp group ip [ip-address[secondary]]

Example:

Router(config-if)# vrrp 1 ip 10.0.0.3

Enables VRRP on an interface and identifies the IP address of the virtual router.

Step 8

Repeat Steps 1 through 7 on each router that will communicate.

--

Step 9

end

Example:

Router(config-if)# end

Returns to privileged EXEC mode.

Configuring VRRP MD5 Authentication Using a Key Chain

Perform this task to configure VRRP MD5 authentication using a key chain. Key chains allow a different key string to be used at different times according to the key chain configuration. VRRP will query the appropriate key chain to obtain the current live key and key ID for the specified key chain.

Note

Interoperability with vendors that may have implemented the RFC 2338 method is not enabled.

Text authentication cannot be combined with MD5 authentication for a VRRP group at any one time. When MD5 authentication is configured, the text authentication field in VRRP hello messages is set to all zeroes on transmit and ignored on receipt, provided the receiving router also has MD5 authentication enabled.

SUMMARY STEPS

1.    enable

2.    configure terminal

3.    key chain name-of-chain

4.    key key-id

5.    key-string string

6.    exit

7.    interface type number

8.    ip address ip-address mask [secondary]

9.    vrrp group priority priority

10.    vrrp group authentication md5 key-chain key-chain

11.    vrrp group ip [ip-address[secondary]]

12.    Repeat Steps 1 through 11 on each router that will communicate.

13.    end

DETAILED STEPS

Command or Action

Purpose

Step 1

enable

Example:

Router> enable

Enables privileged EXEC mode.

- Enter your password if prompted.

Step 2

configure terminal

Example:

Router# configure terminal

Enters global configuration mode.

Step 3

key chain name-of-chain

Example:

Router(config)# key chain vrrp1

Enables authentication for routing protocols and identifies a group of authentication keys.

Step 4

key key-id

Example:

Router(config-keychain)# key 100

Identifies an authentication key on a key chain.

- The key-id must be a number.

Step 5

key-string string

Example:

Router(config-keychain-key)# key-string mno172

Specifies the authentication string for a key.

- The string can be 1 to 80 uppercase or lowercase alphanumeric characters; the first character cannot be a number.

Step 6

exit

Example:

Router(config-keychain-key)# exit

Returns to global configuration mode.

Step 7

interface type number

Example:

Router(config)# interface Ethernet0/1

Configures an interface type and enters interface configuration mode.

Step 8

ip address ip-address mask [secondary]

Example:

Router(config-if)# ip address 10.21.8.32 255.255.255.0

Specifies a primary or secondary IP address for an interface.

Step 9

vrrp group priority priority

Example:

Router(config-if)# vrrp 1 priority 110

Configures VRRP priority.

Step 10

vrrp group authentication md5 key-chain key-chain

Example:

Router(config-if)# vrrp 1 authentication md5 key-chain vrrp1

Configures an authentication MD5 key chain for VRRP MD5 authentication.

- The key chain name must match the name specified in Step 3.

Note:
All routers within the VRRP group must be configured with the same authentication string. If the same authentication string is not configured, the routers in the VRRP group will not communicate with each other and any misconfigured router will change its state to master.

Step 11

vrrp group ip [ip-address[secondary]]

Example:

Router(config-if)# vrrp 1 ip 10.21.8.12

Enables VRRP on an interface and identifies the IP address of the virtual router.

Step 12

Repeat Steps 1 through 11 on each router that will communicate.

--

Step 13

end

Example:

Router(config-if)# end

Returns to privileged EXEC mode.

Verifying the VRRP MD5 Authentication Configuration

SUMMARY STEPS

1.    show vrrp

2.    debug vrrp authentication

DETAILED STEPS

Step 1

show vrrp

Use this command to verify that the authentication is configured correctly:

Example:

Router# show vrrp
Ethernet0/1 - Group 1
State is Master
Virtual IP address is 10.21.0.10
Virtual MAC address is 0000.5e00.0101
Advertisement interval is 1.000 sec
Preemption is enabled
min delay is 0.000 sec
Priority is 100
Authentication MD5, key-string, timeout 30 secs
Master Router is 10.21.0.1 (local), priority is 100
Master Advertisement interval is 1.000 sec
Master Down interval is 3.609 sec

This output shows that MD5 authentication is configured and the f00d4s key string is used. The timeout value is set at 30 seconds.

Step 2

debug vrrp authentication

Use this command to verify that both routers have authentication configured, that the MD5 key ID is the same on each router, and that the MD5 key strings are the same on each router:

Example:

Router1#: debug vrrp authentication
VRRP: Sent: 21016401FE050000AC1801FE0000000000000000
VRRP: HshC: B861CBF1B9026130DD34AED849BEC8A1
VRRP: Rcvd: 21016401FE050000AC1801FE0000000000000000
VRRP: HshC: B861CBF1B9026130DD34AED849BEC8A1
VRRP: HshR: C5E193C6D84533FDC750F85FCFB051E1
VRRP: Grp 1 Adv from 172.24.1.2 has failed MD5 auth
Router2#: debug vrrp authentication
VRRP: Sent: 21016401FE050000AC1801FE0000000000000000
VRRP: HshC: C5E193C6D84533FDC750F85FCFB051E1
VRRP: Rcvd: 21016401FE050000AC1801FE0000000000000000
VRRP: HshC: C5E193C6D84533FDC750F85FCFB051E1
VRRP: HshR: B861CBF1B9026130DD34AED849BEC8A1
VRRP: Grp 1 Adv from 172.24.1.1 has failed MD5 auth

Configuring VRRP Text Authentication

Before You Begin

Interoperability with vendors that may have implemented the RFC 2338 method is not enabled.

Text authentication cannot be combined with MD5 authentication for a VRRP group at any one time. When MD5 authentication is configured, the text authentication field in VRRP hello messages is set to all zeros on transmit and ignored on receipt, provided the receiving router also has MD5 authentication enabled.

SUMMARY STEPS

1.    enable

2.    configure terminal

3.    terminal interface type number

4.    ip address ip-address mask [secondary]

5.    vrrp group authentication text text-string

6.    vrrp group ip ip-address

7.    Repeat Steps 1 through 6 on each router that will communicate.

8.    end

DETAILED STEPS

Command or Action

Purpose

Step 1

enable

Example:

Router> enable

Enables privileged EXEC mode.

- Enter your password if prompted.

Step 2

configure terminal

Example:

Router# configure terminal

Enters global configuration mode.

Step 3

terminal interface type number

Example:

Router(config)# interface Ethernet 0/1

Configures an interface type and enters interface configuration mode.

Step 4

ip address ip-address mask [secondary]

Example:

Router(config-if)# ip address 10.0.0.1 255.255.255.0

Specifies a primary or secondary IP address for an interface.

Step 5

vrrp group authentication text text-string

Example:

Router(config-if)# vrrp 1 authentication text textstring1

Authenticates VRRP packets received from other routers in the group.

- If you configure authentication, all routers within the VRRP group must use the same authentication string.

- The default string is cisco.

Note:
All routers within the VRRP group must be configured with the same authentication string. If the same authentication string is not configured, the routers in the VRRP group will not communicate with each other and any misconfigured router will change its state to master.

Step 6

vrrp group ip ip-address

Example:

Router(config-if)# vrrp 1 ip 10.0.1.20

Enables VRRP on an interface and identifies the IP address of the virtual router.

Step 7

Repeat Steps 1 through 6 on each router that will communicate.

—

Step 8

end

Example:

Router(config-if)# end

Returns to privileged EXEC mode.

Enabling the Router to Send SNMP VRRP Notifications

The VRRP MIB supports SNMP Get operations, which allow network devices to get reports about VRRP groups in a network from the network management station.

Enabling VRRP MIB trap support is performed through the CLI, and the MIB is used for getting the reports. A trap notifies the network management station when a router becomes a Master or backup router. When an entry is configured from the CLI, the RowStatus for that group in the MIB immediately goes to the active state.

SUMMARY STEPS

1.    enable

2.    configure terminal

3.    snmp-server enable traps vrrp

4.    snmp-server host host community-string vrrp

DETAILED STEPS

Command or Action

Purpose

Step 1

enable

Example:

Router> enable

Enables privileged EXEC mode.

- Enter your password if prompted.

Step 2

configure terminal

Example:

Router# configure terminal

Enters global configuration mode.

Step 3

snmp-server enable traps vrrp

Example:

Router(config)#
snmp-server enable traps vrrp

Enables the router to send SNMP VRRP notifications (traps and informs).

Step 4

snmp-server host host community-string vrrp

Example:

Router(config)#
snmp-server host myhost.comp.com public vrrp

Specifies the recipient of an SNMP notification operation.

Configuration Examples for VRRP

- Example: Configuring VRRP

- Example: VRRP Object Tracking

- Example: VRRP Object Tracking Verification

- Example: VRRP MD5 Authentication Configuration Using a Key String

- Example: VRRP MD5 Authentication Configuration Using a Key Chain

- Example: VRRP Text Authentication

- Example: Disabling a VRRP Group on an Interface

- Example: VRRP MIB Trap

Example: Configuring VRRP

In the following example, Router A and Router B each belong to three VRRP groups.

In the configuration, each group has the following properties:

- Group 1:

- Virtual IP address is 10.1.0.10.

- Router A will become the master for this group with priority 120.

- Advertising interval is 3 seconds.

- Preemption is enabled.

- Group 5:

- Router B will become the master for this group with priority 200.

- Advertising interval is 30 seconds.

- Preemption is enabled.

- Group 100:

- Router A will become the master for this group first because it has a higher IP address (10.1.0.2).

- Advertising interval is the default 1 second.

- Preemption is disabled.

Router A

Router(config)# interface GigabitEthernet 1/0/0
Router(config-if)# ip address 10.1.0.2 255.0.0.0
Router(config-if)# vrrp 1 priority 120
Router(config-if)# vrrp 1 authentication cisco
Router(config-if)# vrrp 1 timers advertise 3
Router(config-if)# vrrp 1 timers learn
Router(config-if)# vrrp 1 ip 10.1.0.10
Router(config-if)# vrrp 5 priority 100
Router(config-if)# vrrp 5 timers advertise 30
Router(config-if)# vrrp 5 timers learn
Router(config-if)# vrrp 5 ip 10.1.0.50
Router(config-if)# vrrp 100 timers learn
Router(config-if)# no vrrp 100 preempt
Router(config-if)# vrrp 100 ip 10.1.0.100
Router(config-if)# no shutdown

Router B

Router(config)# interface GigabitEthernet 1/0/0
Router(config-if)# ip address 10.1.0.1 255.0.0.0
Router(config-if)# vrrp 1 priority 100
Router(config-if)# vrrp 1 authentication cisco
Router(config-if)# vrrp 1 timers advertise 3
Router(config-if)# vrrp 1 timers learn
Router(config-if)# vrrp 1 ip 10.1.0.10
Router(config-if)# vrrp 5 priority 200
Router(config-if)# vrrp 5 timers advertise 30
Router(config-if)# vrrp 5 timers learn
Router(config-if)# vrrp 5 ip 10.1.0.50
Router(config-if)# vrrp 100 timers learn
Router(config-if)# no vrrp 100 preempt
Router(config-if)# vrrp 100 ip 10.1.0.100
Router(config-if)# no shutdown

Example: VRRP Object Tracking

In the following example, the tracking process is configured to track the state of the line protocol on serial interface 0/1. VRRP on Ethernet interface 1/0 then registers with the tracking process to be informed of any changes to the line protocol state of serial interface 0/1. If the line protocol state on serial interface 0/1 goes down, then the priority of the VRRP group is reduced by 15.

Router(config)# track 1 interface Serial 0/1 line-protocol
Router(config-track)# exit
Router(config)# interface Ethernet 1/0
Router(config-if)# ip address 10.0.0.2 255.0.0.0
Router(config-if)# vrrp 1 ip 10.0.0.3
Router(config-if)# vrrp 1 priority 120
Router(config-if)# vrrp 1 track 1 decrement 15

Example: VRRP Object Tracking Verification

The following examples verify the configuration shown in the Example: VRRP Object Tracking section:

Router# show vrrp

Ethernet1/0 - Group 1
State is Master
Virtual IP address is 10.0.0.3
Virtual MAC address is 0000.5e00.0101
Advertisement interval is 1.000 sec
Preemption is enabled
min delay is 0.000 sec
Priority is 105
Track object 1 state Down decrement 15
Master Router is 10.0.0.2 (local), priority is 105
Master Advertisement interval is 1.000 sec
Master Down interval is 3.531 sec
Router# show track

Track 1
Interface Serial0/1 line-protocol
Line protocol is Down (hw down)
1 change, last change 00:06:53
Tracked by:
VRRP Ethernet1/0 1

Example: VRRP MD5 Authentication Configuration Using a Key String

The following example shows how to configure MD5 authentication using a key string and timeout of 30 seconds:

Router(config)# interface Ethernet0/1
Router(config-if)# description ed1-cat5a-7/10
Router(config-if)# vrrp 1 ip 10.21.0.10
Router(config-if)# vrrp 1 priority 110
Router(config-if)# vrrp 1 authentication md5 key-string f00c4s timeout 30
Router(config-if)# exit

Example: VRRP MD5 Authentication Configuration Using a Key Chain

The following example shows how to configure MD5 authentication using a key chain:

Router(config)# key chain vrrp1
Router(config-keychain)# key 1
Router(config-keychain-key)# key-string f00c4s
Router(config-keychain-key)# exit
Router(config)#interface ethernet0/1
Router(config-if)# description ed1-cat5a-7/10
Router(config-if)# vrrp 1 priority 110
Router(config-if)# vrrp 1 authentication md5 key-chain vrrp1
Router(config-if)# vrrp 1 ip 10.21.0.10

In this example, VRRP queries the key chain to obtain the current live key and key ID for the specified key chain.

Example: VRRP Text Authentication

The following example shows how to configure VRRP text authentication using a text string:

Router(config)# interface GigabitEthernet 0/0/0
Router(config)# ip address 10.21.8.32 255.255.255.0
Router(config-if)# vrrp 10 authentication text stringxyz
Router(config-if)# vrrp 10 ip 10.21.8.10

Example: Disabling a VRRP Group on an Interface

The following example shows how to disable one VRRP group on GigabitEthernet interface 0/0/0 while retaining VRRP for group 2 on GigabitEthernet interface 1/0/0:

Router(config)# interface GigabitEthernet 0/0/0
Router(config-if)# ip address 10.24.1.1 255.255.255.0
Router(config-if)# vrrp 1 ip 10.24.1.254
Router(config-if)# vrrp 1 shutdown
Router(config-if)# exit
Router(config)# interface GigabitEthernet 1/0/0
Router(config-if)# ip address 10.168.42.1 255.255.255.0
Router(config-if)# vrrp 2 ip 10.168.42.254

Example: VRRP MIB Trap

Router(config)# snmp-server enable traps vrrp
Router(config)# snmp-server host 10.1.1.0 community abc vrrp

Additional References for Configuring VRRP

Related Documents

Related Topic

Document Title

Cisco IOS commands

Cisco IOS Master Commands List, All Releases

VRRP commands

Cisco IOS IP Application Services Command Reference

Object tracking

Configuring Enhanced Object Tracking

Hot Standby Routing Protocol (HSRP)

Configuring HSRP

In Service Software Upgrace (ISSU)

"Cisco IOS In Service Software Upgrade Process" in the Cisco IOSHigh Availability Configuration Guide

Gateway Load Balancing Protocol (GLBP)

Configuring GLBP

Stateful Switchover

The Stateful Switchover section in the Cisco IOS High Availability Configuration Guide

MIBs

MIBs

MIBs Link

VRRP MIB

To locate and download MIBs for selected platforms, Cisco software releases, and feature sets, use Cisco MIB Locator found at the following URL:

Click Here

Standards and RFCs

Standard/RFC

Title

RFC 2338

Virtual Router Redundancy Protocol

RFC 2787

Definitions of Managed Objects for the Virtual Router Redundancy Protocol

RFC 3768

Virtual Router Redundancy Protocol (VRRP)

Technical Assistance

Description

Link

The Cisco Support and Documentation website provides online resources to download documentation, software, and tools. Use these resources to install and configure the software and to troubleshoot and resolve technical issues with Cisco products and technologies. Access to most tools on the Cisco Support and Documentation website requires a Cisco.com user ID and password.

Click Here

Feature Information for VRRP

The following table provides release information about the feature or features described in this module. This table lists only the software release that introduced support for a given feature in a given software release train. Unless noted otherwise, subsequent releases of that software release train also support that feature.

Use Cisco Feature Navigator to find information about platform support and Cisco software image support. To access Cisco Feature Navigator, go to Click Here . An account on Cisco.com is not required.

Feature Information for VRRP

Feature Name

Releases

Feature Configuration Information

FHRP—VRRP Support for BVI

12.3(14)T

The FHRP—VRRP Support for BVI feature adds the capability to configure VRRP on Bridged Virtual Interfaces (BVIs). This functionality is similar to the existing HSRP support for BVIs.

ISSU—VRRP

12.2(33)SRC

VRRP supports In Service Software Upgrade (ISSU). ISSU allows a high-availability (HA) system to run in Stateful Switchover (SSO) mode even when different versions of Cisco IOS software are running on the active and standby Route Processors (RPs) or line cards.

This feature provides customers with the same level of HA functionality for planned outages due to software upgrades as is available with SSO for unplanned outages. That is, the system can switch over to a secondary RP and continue forwarding packets without session loss and with minimal or no packet loss.

This feature is enabled by default.

There are no new or modified commands for this feature.

SSO—VRRP

12.2(33)SRC 12.2(33)SXI

VRRP is now SSO aware. VRRP can detect when a router is failing over to the secondary RP and continue in its current VRRP group state.

This feature is enabled by default.

The following commands were introduced or modified by this feature: debug vrrp ha,vrrp sso, show vrrp.

Virtual Router Redundancy Protocol

Cisco IOS XE 3.1.0SG 12.2(13)T 12.2(14)S 15.0(1)S

VRRP enables a group of routers to form a single virtual router to provide redundancy. The LAN clients can then be configured with the virtual router as their default gateway. The virtual router, representing a group of routers, is also known as a VRRP group.

The following commands were introduced by this feature: debug vrrp all, debug vrrp error, debug vrrp events, debug vrrp packets, debug vrrp state, show vrrp, show vrrp interface, vrrp authentication, vrrp description, vrrp ip, vrrp preempt, vrrp priority, vrrp timers advertise, vrrp timers learn.

VRRP MD5 Authentication

12.3(14)T

The VRRP MD5 Authentication feature provides a method of authenticating peers using a more simple method than the method in RFC 2338.

The following command was introduced by this feature: debug vrrp authentication.

The following commands were modified by this feature: vrrp authentication and show vrrp.

VRRP MIB—RFC 2787

12.3(11)T

The VRRP MIB--RFC 2787 feature enables an enhancement to the MIB for use with SNMP-based network management. The feature adds support for configuring, monitoring, and controlling routers that use VRRP.

The following command was introduced by this feature: vrrp shutdown.

The following commands were modified by this feature: snmp-server enable trapsandsnmp-server host.

VRRP Object Tracking

12.3(2)T 12.2(25)S

The VRRP Object Tracking feature extends the capabilities of the VRRP to allow tracking of specific objects within the router that can alter the priority level of a virtual router for a VRRP group.

The following command was introduced by this feature: vrrp track.

The following command was modified by this feature: show track.

Glossary

virtual IP address owner —The VRRP router that owns the IP address of the virtual router. The owner is the router that has the virtual router address as its physical interface address.

virtual router —One or more VRRP routers that form a group. The virtual router acts as the default gateway router for LAN clients. Also known as a VRRP group.

virtual router backup —One or more VRRP routers that are available to assume the role of forwarding packets if the virtual router master fails.

virtual router master —The VRRP router that is currently responsible for forwarding packets sent to the IP addresses of the virtual router. Usually the virtual router master also functions as the IP address owner.

VRRP router --A router that is running VRRP.

Chapter 12. VRRPv3 Protocol Support

Virtual Router Redundancy Protocol (VRRP) enables a group of devices to form a single virtual device to provide redundancy. The LAN clients can then be configured with the virtual device as their default gateway. The virtual device, representing a group of devices, is also known as a VRRP group. The VRRP version 3 (v3) Protocol Support feature provides the capability to support IPv4 and IPv6 addresses while VRRP version 2 (v2) only supports IPv4 addresses. This module explains concepts related to VRRPv3 and describes how to create and customize a VRRP group in a network. Benefits of using VRRPv3 Protocol Support include the following:

- Interoperability in multi-vendor environments.

- VRRPv3 supports usage of IPv4 and IPv6 addresses while VRRPv2 only supports IPv4 addresses.

- Improved scalability through the use of VRRS Pathways.

Note

In this module, VRRP and VRRPv3 are used interchangeably.

- Finding Feature Information

- Restrictions for VRRPv3 Protocol Support

- Information About VRRPv3 Protocol Support

- How to Configure VRRPv3 Protocol Support

- Configuration Examples for VRRPv3 Protocol Support

- Additional References for VRRPv3 Protocol Support

- Feature Information for VRRPv3 Protocol Support

- Glossary

Finding Feature Information

Your software release may not support all the features documented in this module. For the latest caveats and feature information, see Bug Search Tool and the release notes for your platform and software release. To find information about the features documented in this module, and to see a list of the releases in which each feature is supported, see the feature information table.

Use Cisco Feature Navigator to find information about platform support and Cisco software image support. To access Cisco Feature Navigator, go to Click Here . An account on Cisco.com is not required.

Restrictions for VRRPv3 Protocol Support

- VRRPv3 is not intended as a replacement for existing dynamic protocols. VRRPv3 is designed for use over multi-access, multicast, or broadcast capable Ethernet LANs.

- VRRPv3 is supported on Ethernet, Fast Ethernet, Bridge Group Virtual Interface (BVI), and Gigabit Ethernet interfaces, and on Multiprotocol Label Switching (MPLS) Virtual Private Networks (VPNs), VRF-aware MPLS VPNs, and VLANs.

- Because of the forwarding delay that is associated with the initialization of a BVI interface, you must not configure the VRRPv3 advertise timer to a value lesser than the forwarding delay on the BVI interface. If you configure the VRRPv3 advertise timer to a value equal to or greater than the forwarding delay on the BVI interface, the setting prevents a VRRP device on a recently initialized BVI interface from unconditionally taking over the master role. Use the bridge forward-time command to set the forwarding delay on the BVI interface. Use the vrrp timers advertise command to set the VRRP advertisement timer.

- VRRPv3 does not support Stateful Switchover (SSO).

- VRRPv3 protocol does not support authentication.

- Full network redundancy can only be achieved if VRRP operates over the same network path as the VRRS Pathway redundant interfaces. For full redundancy, the following restrictions apply:

- VRRS pathways should not share a different physical interface as the parent VRRP group or be configured on a sub-interface having a different physical interface as the parent VRRP group.

- VRRS pathways should not be configured on Switch Virtual Interface (SVI) interfaces as long as the associated VLAN does not share the same trunk as the VLAN on which the parent VRRP group is configured.

Information About VRRPv3 Protocol Support

- VRRPv3 Benefits

- VRRP Device Priority and Preemption

- VRRP Advertisements

VRRPv3 Benefits

Support for IPv4 and IPv6

VRRPv3 supports IPv4 and IPv6 address families while VRRPv2 only supports IPv4 addresses.

Note

When VRRPv3 is in use, VRRPv2 is unavailable. For VRRPv3 to be configurable, the fhrp version vrrp v3 command must be used in global configuration mode

Redundancy

VRRP enables you to configure multiple devices as the default gateway device, which reduces the possibility of a single point of failure in a network.

Load Sharing

You can configure VRRP in such a way that traffic to and from LAN clients can be shared by multiple devices, thereby sharing the traffic load more equitably between available devices.

Multiple Virtual Devices

VRRP supports up to 255 virtual devices (VRRP groups) on a device physical interface, subject to restrictions in scaling. Multiple virtual device support enables you to implement redundancy and load sharing in your LAN topology. In scaled environments, VRRS Pathways should be used in combination with VRRP control groups.

Multiple IP Addresses

The virtual device can manage multiple IP addresses, including secondary IP addresses. Therefore, if you have multiple subnets configured on an Ethernet interface, you can configure VRRP on each subnet.

Note

To utilize secondary IP addresses in a VRRP group, a primary address must be configured on the same group.

Preemption

The redundancy scheme of VRRP enables you to preempt a virtual device backup that has taken over for a failing virtual device master with a higher priority virtual device backup that has become available.

Note

Preemption of a lower priority master device is enabled with an optional delay.

Advertisement Protocol

VRRP uses a dedicated Internet Assigned Numbers Authority (IANA) standard multicast address for VRRP advertisements. For IPv4, the multicast address is 224.0.0.18. For IPv6, the multicast address is FF02:0:0:0:0:0:0:12. This addressing scheme minimizes the number of devices that must service the multicasts and allows test equipment to accurately identify VRRP packets on a segment. The IANA has assigned VRRP the IP protocol number 112.

VRRP Device Priority and Preemption

An important aspect of the VRRP redundancy scheme is VRRP device priority. Priority determines the role that each VRRP device plays and what happens if the virtual device master fails.

If a VRRP device owns the IP address of the virtual device and the IP address of the physical interface, this device will function as a virtual device master.

Priority also determines if a VRRP device functions as a virtual device backup and the order of ascendancy to becoming a virtual device master if the virtual device master fails. You can configure the priority of each virtual device backup with a value of 1 through 254 using the priority command (use the vrrp address-family command to enter the VRRP configuration mode and access the priority option).

For example, if device A, the virtual device master in a LAN topology, fails, an election process takes place to determine if virtual device backups B or C should take over. If devices B and C are configured with the priorities of 101 and 100, respectively, device B is elected to become virtual device master because it has the higher priority. If devices B and C are both configured with the priority of 100, the virtual device backup with the higher IP address is elected to become the virtual device master.

By default, a preemptive scheme is enabled whereby a higher priority virtual device backup that becomes available takes over from the virtual device backup that was elected to become virtual device master. You can disable this preemptive scheme using the no preempt command (use the vrrp address-family command to enter the VRRP configuration mode, and enter the no preempt command). If preemption is disabled, the virtual device backup that is elected to become virtual device master remains the master until the original virtual device master recovers and becomes master again.

Note

Preemption of a lower priority master device is enabled with an optional delay.

VRRP Advertisements

The virtual device master sends VRRP advertisements to other VRRP devices in the same group. The advertisements communicate the priority and state of the virtual device master. The VRRP advertisements are encapsulated into either IPv4 or IPv6 packets (based on the VRRP group configuration) and sent to the appropriate multicast address assigned to the VRRP group. For IPv4, the multicast address is 224.0.0.18. For IPv6, the multicast address is FF02:0:0:0:0:0:0:12. The advertisements are sent every second by default and the interval is configurable.

Cisco devices allow you to configure millisecond timers, which is a change from VRRPv2. You need to manually configure the millisecond timer values on both the primary and the backup devices. The master advertisement value displayed in the show vrrp command output on the backup devices is always 1 second because the packets on the backup devices do not accept millisecond values.

You must use millisecond timers where absolutely necessary and with careful consideration and testing. Millisecond values work only under favorable circumstances. The use of the millisecond timer values is compatible with third party vendors, as long as they also support VRRPv3. You can specify a timer value between 100 milliseconds and 40000 milliseconds.

How to Configure VRRPv3 Protocol Support

- Enabling VRRPv3 on a Device

- Creating and Customizing a VRRP Group

- Configuring the Delay Period Before FHRP Client Initialization

Enabling VRRPv3 on a Device

To enable VRRPv3 on a device, perform the following task:

SUMMARY STEPS

1.    enable

2.    configure terminal

3.    fhrp version vrrp v3

4.    end

DETAILED STEPS

Command or Action

Purpose

Step 1

enable

Example:

Device> enable

Enables privileged EXEC mode.

- Enter your password if prompted.

Step 2

configure terminal

Example:

Device# configure terminal

Enters global configuration mode.

Step 3

fhrp version vrrp v3

Example:

Device(config)# fhrp version vrrp v3

Enables the ability to configure VRRPv3 and VRRS.

Note:
When VRRPv3 is in use, VRRPv2 is unavailable.

Step 4

end

Example:

Device(config)# end

Returns to privileged EXEC mode.

Creating and Customizing a VRRP Group

To create a VRRP group, perform the following task. Steps 6 to 14 denote customizing options for the group, and they are optional:

SUMMARY STEPS

1.    enable

2.    configure terminal

3.    fhrp version vrrp v3

4.    interface type number

5.    vrrp group-id address-family {ipv4 | ipv6}

6.    address ip-address [primary | secondary]

7.    description group-description

8.    match-address

9.    preempt delay minimum seconds

10.    priority priority-level

11.    timers advertise interval

12.    vrrpv2

13.    vrrs leader vrrs-leader-name

14.    shutdown

15.    end

DETAILED STEPS

Command or Action

Purpose

Step 1

enable

Example:

Device> enable

Enables privileged EXEC mode.

- Enter your password if prompted.

Step 2

configure terminal

Example:

Device# configure terminal

Enters global configuration mode.

Step 3

fhrp version vrrp v3

Example:

Device(config)# fhrp version vrrp v3

Enables the ability to configure VRRPv3 and VRRS.

Note:
When VRRPv3 is in use, VRRPv2 is unavailable.

Step 4

interface type number

Example:

Device(config)# interface GigabitEthernet 0/0/0

Enters interface configuration mode.

Step 5

vrrp group-id address-family {ipv4 | ipv6}

Example:

Device(config-if)# vrrp 3 address-family ipv4

Creates a VRRP group and enters VRRP configuration mode.

Step 6

address ip-address [primary | secondary]

Example:

Device(config-if-vrrp)# address 100.0.1.10 primary

Specifies a primary or secondary address for the VRRP group.

Note:   VRRPv3 for IPv6 requires that a primary virtual link-local IPv6 address is configured to allow the group to operate. After the primary link-local IPv6 address is established on the group, you can add the secondary global addresses.

Step 7

description group-description

Example:

Device(config-if-vrrp)# description group 3

(Optional) Specifies a description for the VRRP group.

Step 8

match-address

Example:

Device(config-if-vrrp)# match-address

(Optional) Matches secondary address in the advertisement packet against the configured address.

- Secondary address matching is enabled by default.

Step 9

preempt delay minimum seconds

Example:

Device(config-if-vrrp)# preempt delay minimum 30

(Optional) Enables preemption of lower priority master device with an optional delay.

- Preemption is enabled by default.

Step 10

priority priority-level

Example:

Device(config-if-vrrp)# priority 3

(Optional) Specifies the priority value of the VRRP group.

- The priority of a VRRP group is 100 by default.

Step 11

timers advertise interval

Example:

Device(config-if-vrrp)# timers advertise 1000

(Optional) Sets the advertisement timer in milliseconds.

- The advertisement timer is set to 1000 milliseconds by default.

Step 12

vrrpv2

Example:

Device(config-if-vrrp)# vrrpv2

(Optional) Enables support for VRRPv2 simultaneously, so as to interoperate with devices which only support VRRP v2.

- VRRPv2 is disabled by default.

Step 13

vrrs leader vrrs-leader-name

Example:

Device(config-if-vrrp)# vrrs leader leader-1

(Optional) Specifies a leader's name to be registered with VRRS and to be used by followers.

- A registered VRRS name is unavailable by default.

Step 14

shutdown

Example:

Device(config-if-vrrp)# shutdown

(Optional) Disables VRRP configuration for the VRRP group.

- VRRP configuration is enabled for a VRRP group by default.

Step 15

end

Example:

Device(config)# end

Returns to privileged EXEC mode.

Configuring the Delay Period Before FHRP Client Initialization

To configure the delay period before the initialization of all FHRP clients on an interface, perform the following task:

SUMMARY STEPS

1.    enable

2.    configure terminal

3.    fhrp version vrrp v3

4.    interface type number

5.    fhrp delay {[minimum] [reload] seconds}

6.    end

DETAILED STEPS

Command or Action

Purpose

Step 1

enable

Example:

Device> enable

Enables privileged EXEC mode.

- Enter your password if prompted.

Step 2

configure terminal

Example:

Device# configure terminal

Enters global configuration mode.

Step 3

fhrp version vrrp v3

Example:

Device(config)# fhrp version vrrp v3

Enables the ability to configure VRRPv3 and VRRS.

Note:
When VRRPv3 is in use, VRRPv2 is unavailable.

Step 4

interface type number

Example:

Device(config)# interface GigabitEthernet 0/0/0

Enters interface configuration mode.

Step 5

fhrp delay {[minimum] [reload] seconds}

Example:

Device(config-if)# fhrp delay minimum 5

Specifies the delay period for the initialization of FHRP clients after an interface comes up.

- The range is 0-3600 seconds.

Step 6

end

Example:

Device(config)# end

Returns to privileged EXEC mode.

Configuration Examples for VRRPv3 Protocol Support

- Example: Enabling VRRPv3 on a Device

- Example: Creating and Customizing a VRRP Group

- Example: Configuring the Delay Period Before FHRP Client Initialization

- Example: VRRP Status, Configuration, and Statistics Details

Example: Enabling VRRPv3 on a Device

The following example shows how to enable VRRPv3 on a device:

Device> enable
Device# configure terminal
Device(config)# fhrp version vrrp v3
Device(config-if-vrrp)# end

Example: Creating and Customizing a VRRP Group

The following example shows how to create and customize a VRRP group:

Device> enable
Device# configure terminal
Device(config)# fhrp version vrrp v3
Device(config)# interface gigabitethernet0/0
Device(config-if)# vrrp 3 address-family ipv4
Device(config-if-vrrp)# address 100.0.1.10 primary
Device(config-if-vrrp)# description group 3
Device(config-if-vrrp)# match-address
Device(config-if-vrrp)# preempt delay minimum 30
Device(config-if-vrrp)# end

Note

In the above example, the fhrp version vrrp v3 command is used in the global configuration mode.

Example: Configuring the Delay Period Before FHRP Client Initialization

The following example shows how to configure the delay period before FHRP client initialization :

Device> enable
Device# configure terminal
Device(config)# fhrp version vrrp v3
Device(config)# interface gigabitethernet0/0
Device(config-if)# fhrp delay minimum 5
Device(config-if-vrrp)# end

Note

In the above example, a five-second delay period is specified for the initialization of FHRP clients after the interface comes up. You can specify a delay period between 0 and 3600 seconds.

Example: VRRP Status, Configuration, and Statistics Details

The following is a sample output of the status, configuration and statistics details for a VRRP group:

Device> enable
Device# show vrrp detail

Ethernet0/0 - Group 1 - Address-Family IPv4

State is MASTER
State duration 3.707 secs
Virtual IP address is 1.0.0.10
Virtual MAC address is 0000.5E00.0101
Advertisement interval is 1000 msec
Preemption enabled
Priority is 100
Master Router is 1.0.0.1 (local), priority is 100
Master Advertisement interval is 1000 msec (expires in 686 msec)
Master Down interval is unknown
State is MASTER
State duration 3.707 secs
VRRPv3 Advertisements: sent 5 (errors 0) - rcvd 0
VRRPv2 Advertisements: sent 0 (errors 0) - rcvd 0
Group Discarded Packets: 0
VRRPv2 incompatibility: 0
IP Address Owner conflicts: 0
Invalid address count: 0
IP address configuration mismatch : 0
Invalid Advert Interval: 0
Adverts received in Init state: 0
Invalid group other reason: 0
Group State transition:
Init to master: 0
Init to backup: 1 (Last change Mon Jul 30 16:42:01.856)
Backup to master: 1 (Last change Mon Jul 30 16:42:05.469)
Master to backup: 0
Master to init: 0
Backup to init: 0

Device# exit

Additional References for VRRPv3 Protocol Support

Related Documents

Related Topic

Document Title

Cisco IOS commands

Master Commands List, All Releases

FHRP commands

First Hop Redundancy Protocols Command Reference

Configuring VRRPv2

Configuring VRRP

Standards and RFCs

Standard/RFC

Title

RFC5798

Virtual Router Redundancy Protocol

RFC 6527

Definitions of Managed Objects for the Virtual Router Redundancy Protocol Version 3 (VRRPv3)

MIBs

MIB

MIBs Link

VRRPv3 MIB

To locate and download MIBs for selected platforms, Cisco software releases, and feature sets, use Cisco MIB Locator found at the following URL:

Click Here

Technical Assistance

Description

Link

The Cisco Support and Documentation website provides online resources to download documentation, software, and tools. Use these resources to install and configure the software and to troubleshoot and resolve technical issues with Cisco products and technologies. Access to most tools on the Cisco Support and Documentation website requires a Cisco.com user ID and password.

Click Here

Feature Information for VRRPv3 Protocol Support

The following table provides release information about the feature or features described in this module. This table lists only the software release that introduced support for a given feature in a given software release train. Unless noted otherwise, subsequent releases of that software release train also support that feature.

Use Cisco Feature Navigator to find information about platform support and Cisco software image support. To access Cisco Feature Navigator, go to Click Here . An account on Cisco.com is not required.

Feature Information for VRRPv3 Protocol Support

Feature Name

Releases

Feature Information

VRRPv3 MIB based on RFC 6527

15.7(3)M1

This feature enables you to define objects for configuring, monitoring, and controlling routers that employ the Virtual Router Redundancy Protocol Version 3 (VRRPv3) for both IPv4 and IPv6 networks.

VRRPv3 Protocol Support

15.2(4)M

VRRP enables a group of devices to form a single virtual device to provide redundancy. The LAN clients can then be configured with the virtual device as their default gateway. The virtual device, representing a group of devices, is also known as a VRRP group. The VRRPv3 Protocol Support feature provides the capability to support IPv4 and IPv6 addresses.

The following commands were introduced or modified: fhrp delay, show vrrp, vrrp address-family.

Glossary

Virtual IP address owner—The VRRP device that owns the IP address of the virtual device. The owner is the device that has the virtual device address as its physical interface address.

Virtual device—One or more VRRP devices that form a group. The virtual device acts as the default gateway device for LAN clients. The virtual device is also known as a VRRP group.

Virtual device backup—One or more VRRP devices that are available to assume the role of forwarding packets if the virtual device master fails.

Virtual device master—The VRRP device that is currently responsible for forwarding packets sent to the IP addresses of the virtual device. Usually, the virtual device master also functions as the IP address owner.

VRRP device—A device that is running VRRP.

Chapter 13. VRRPv3: Object Tracking Integration

Virtual Router Redundancy Protocol (VRRP) enables a group of devices to form a single virtual device to provide redundancy. The LAN clients then can be configured with the virtual device as the default gateway. The virtual device, representing a group of devices, is also known as a VRRP group. The VRRPv3: Object Tracking Integration feature allows you to track the behavior of an object and receive notifications of changes. This module explains how object tracking, in particular the tracking of IPv6 objects, is integrated into VRRP version 3 (VRRPv3) and describes how to track an IPv6 object using a VRRPv3 group. See the “VRRP Object Tracking” section for more information on object tracking.

- Finding Feature Information

- Additional References for VRRPv3: Object Tracking Integration

- Feature Information for VRRPv3: Object Tracking Integration

Finding Feature Information

Your software release may not support all the features documented in this module. For the latest caveats and feature information, see Bug Search Tool and the release notes for your platform and software release. To find information about the features documented in this module, and to see a list of the releases in which each feature is supported, see the feature information table.

Use Cisco Feature Navigator to find information about platform support and Cisco software image support. To access Cisco Feature Navigator, go to Click Here . An account on Cisco.com is not required.

VRRP Object Tracking

Object tracking is an independent process that manages creating, monitoring, and removing tracked objects such as the state of the line protocol of an interface. Clients such as the Hot Standby Router Protocol (HSRP), Gateway Load Balancing Protocol (GLBP), and VRRP register their interest with specific tracked objects and act when the state of an object changes.

Each tracked object is identified by a unique number that is specified on the tracking CLI. Client processes such as VRRP use this number to track a specific object.

The tracking process periodically polls the tracked objects and notes any change of value. The changes in the tracked object are communicated to interested client processes, either immediately or after a specified delay. The object values are reported as either up or down.

VRRP object tracking gives VRRP access to all the objects available through the tracking process. The tracking process allows you to track individual objects such as a the state of an interface line protocol, state of an IP route, or the reachability of a route.

VRRP provides an interface to the tracking process. Each VRRP group can track multiple objects that may affect the priority of the VRRP device. You specify the object number to be tracked and VRRP is notified of any change to the object. VRRP increments (or decrements) the priority of the virtual device based on the state of the object being tracked.

How VRRP Object Tracking Affects the Priority of a Device

The priority of a device can change dynamically if it has been configured for object tracking and the object that is being tracked goes down. The tracking process periodically polls the tracked objects and notes any change of value. The changes in the tracked object are communicated to VRRP, either immediately or after a specified delay. The object values are reported as either up or down. Examples of objects that can be tracked are the line protocol state of an interface or the reachability of an IP route. If the specified object goes down, the VRRP priority is reduced. The VRRP device with the higher priority can now become the virtual device master if it has the vrrp preempt command configured. See the “VRRP Object Tracking” section for more information on object tracking.

Tracking an IPv6 Object using VRRPv3

SUMMARY STEPS

1.    fhrp version vrrp v3

2.    interface type number

3.    vrrp group-id address-family ipv6

4.    track object-number decrement number

5.    end

DETAILED STEPS

Command or Action

Purpose

Step 1

fhrp version vrrp v3

Example:

Device(config)# fhrp version vrrp v3

Enables you to configure Virtual Router Redundancy Protocol version 3 (VRRPv3) and Virtual Router Redundancy Service (VRRS) on a device.

Note:
When VRRPv3 is in use, VRRPv2 is unavailable.

Step 2

interface type number

Example:

Device(config)# interface GigabitEthernet 0/0/0

Specifies an interface and enters interface configuration mode.

Step 3

vrrp group-id address-family ipv6

Example:

Device(config-if)# vrrp 1 address-family ipv6

Creates a VRRP group for IPv6 and enters VRRP configuration mode.

Step 4

track object-number decrement number

Example:

Device(config-if-vrrp)# track 1 decrement 20

Configures the tracking process to track the state of the IPv6 object using the VRRPv3 group. VRRP on Ethernet interface 0/0 then registers with the tracking process to be informed of any changes to the IPv6 object on the VRRPv3 group. If the IPv6 object state on serial interface VRRPv3 goes down, then the priority of the VRRP group is reduced by 20.

Step 5

end

Example:

Device(config-if-vrrp)# end

Returns to privileged EXEC mode.

Example: Tracking an IPv6 Object using VRRPv3

In the following example, the tracking process is configured to track the state of the IPv6 object using the VRRPv3 group. VRRP on GigabitEthernet interface 0/0/0 then registers with the tracking process to be informed of any changes to the IPv6 object on the VRRPv3 group. If the IPv6 object state on serial interface VRRPv3 goes down, then the priority of the VRRP group is reduced by 20:

Device(config)# fhrp version vrrp v3
Device(config)# interface GigabitEthernet 0/0/0
Device(config-if)# vrrp 1 address-family ipv6
Device(config-if-vrrp)# track 1 decrement 20

Example: Verifying VRRP IPv6 Object Tracking

Device# show vrrp

Ethernet0/0 - Group 1 - Address-Family IPv4
State is BACKUP
State duration 1 mins 41.856 secs
Virtual IP address is 172.24.1.253
Virtual MAC address is 0000.5E00.0101
Advertisement interval is 1000 msec
Preemption enabled
Priority is 80 (configured 100)
Track object 1 state Down decrement 20
Master Router is 172.24.1.2, priority is 100
Master Advertisement interval is 1000 msec (learned)
Master Down interval is 3609 msec (expires in 3297 msec)

Device# show track ipv6 route brief

Track Type        Instance                   Parameter        State Last Change
601   ipv6 route  3172::1/32                 metric threshold Down  00:08:55
602   ipv6 route  3192:ABCD::1/64            metric threshold Down  00:08:55
603   ipv6 route  3108:ABCD::CDEF:1/96       metric threshold Down  00:08:55
604   ipv6 route  3162::EF01/16              metric threshold Down  00:08:55
605   ipv6 route  3289::2/64                 metric threshold Down  00:08:55
606   ipv6 route  3888::1200/64              metric threshold Down  00:08:55
607   ipv6 route  7001::AAAA/64              metric threshold Down  00:08:55
608   ipv6 route  9999::BBBB/64              metric threshold Down  00:08:55
611   ipv6 route  1111::1111/64              reachability     Down  00:08:55
612   ipv6 route  2222:3333::4444/64         reachability     Down  00:08:55
613   ipv6 route  5555::5555/64              reachability     Down  00:08:55
614   ipv6 route  3192::1/128                reachability     Down  00:08:55

Additional References for VRRPv3: Object Tracking Integration

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Feature Information for VRRPv3: Object Tracking Integration

Feature Information for VRRPv3: Object Tracking Integration

Feature Name

Releases

Feature Information

VRRPv3: Object Tracking Integration

15.3(3)M

The VRRPv3: Object Tracking Integration feature allows you to use a VRRPv3 group to track an object.

The following commands were introduced or modified: fhrp version vrrp v3, show vrrp, track (VRRP).