Restrictions for HSRP BFD Peering
Hot Standby Router Protocol (HSRP) support for Bidirectional Forwarding Detection (BFD) is not available for all platforms and interfaces.
The documentation set for this product strives to use bias-free language. For the purposes of this documentation set, bias-free is defined as language that does not imply discrimination based on age, disability, gender, racial identity, ethnic identity, sexual orientation, socioeconomic status, and intersectionality. Exceptions may be present in the documentation due to language that is hardcoded in the user interfaces of the product software, language used based on RFP documentation, or language that is used by a referenced third-party product. Learn more about how Cisco is using Inclusive Language.
Hot Standby Router Protocol (HSRP) support for Bidirectional Forwarding Detection (BFD) is not available for all platforms and interfaces.
The following section provides an overiew of 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.
The following sections provide information about configuring HSRP BFD Peering:
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.
Command or Action | Purpose | |
---|---|---|
Step 1 |
enable Example:
|
Enables privileged EXEC mode.
|
Step 2 |
configure terminal Example:
|
Enters global configuration mode. |
Step 3 |
interface type number Example:
|
Enters interface configuration mode. |
Step 4 |
bfd interval milliseconds min_rx milliseconds multiplier interval-multiplier Example:
|
Enables BFD on the interface. |
Step 5 |
end Example:
|
Exits interface configuration mode. |
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 proceed with this task:
HSRP must be running on all participating devices.
Cisco Express Forwarding must be enabled.
Command or Action | Purpose | |
---|---|---|
Step 1 |
enable Example:
|
Enables privileged EXEC mode.
|
Step 2 |
configure terminal Example:
|
Enters global configuration mode. |
Step 3 |
ip cef [distributed ] Example:
|
Enables Cisco Express Forwarding or distributed Cisco Express Forwarding. |
Step 4 |
interface type number Example:
|
Enters interface configuration mode. |
Step 5 |
ip address ip-address mask Example:
|
Configures an IP address for the interface. |
Step 6 |
standby [group-number ] ip [ip-address [secondary ]] Example:
|
Activates HSRP. |
Step 7 |
standby bfd Example:
|
(Optional) Enables HSRP support for BFD on the interface. |
Step 8 |
exit Example:
|
Exits interface configuration mode. |
Step 9 |
standby bfd all-interfaces Example:
|
(Optional) Enables HSRP support for BFD on all interfaces. |
Step 10 |
exit Example:
|
Exits global configuration mode. |
Step 11 |
show standby [neighbors ] Example:
|
(Optional) Displays information about HSRP support for BFD. |
To verify Hot Standby Router Protocol (HSRP) Bidirectional Forwarding Detection (BFD) peering, use any of the following optional commands.
Step 1 |
show standby Use the show standby command to display HSRP information. Example:
|
Step 2 |
show standby brief Use the show standby brief command to display HSRP standby device information in brief. Example:
|
Step 3 |
show standby neighbors [type number ] Use the show standby neighbors command to display information about HSRP peer devices on an interface. Example:
|
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:
|
Step 5 |
show bfd neighbors details Use the details keyword to display BFD protocol parameters and timers for each neighbor. Example:
|
This section shows an example of configuring 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.
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
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
This table provides release and related information for the features explained in this module.
These features are available in all the releases subsequent to the one they were introduced in, unless noted otherwise.
Release |
Feature |
Feature Information |
---|---|---|
Cisco IOS XE Gibraltar 16.11.1 |
HSRP BFD Peering |
The HSRP BFD Peering feature introduces BFD in the HSRP group member health monitoring system. HSRP supports BFD as a part of the HSRP group member health monitoring system. |
Use the Cisco Feature Navigator to find information about platform and software image support. To access Cisco Feature Navigator, go to http://www.cisco.com/go/cfn.