Implementing VRRP

The Virtual Router Redundancy Protocol (VRRP) feature allows for transparent failover at the first-hop IP router, enabling a group of routers to form a single virtual router.

Feature History for Implementing VRRP

Release

Modification

Release 5.0.0

This feature was introduced.

Prerequisites for Implementing VRRP on Cisco IOS XR Software

You must be in a user group associated with a task group that includes the proper task IDs. The command reference guides include the task IDs required for each command. If you suspect user group assignment is preventing you from using a command, contact your AAA administrator for assistance.

Information About Implementing VRRP

To implement VRRP on Cisco IOS XR software , you need to understand the following concepts:

VRRP Overview

A LAN client can use a dynamic process or static configuration to determine which router should be the first hop to a particular remote destination. The client 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 responds 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.

  • IRDP (ICMP Router Discovery Protocol) 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.

The Virtual Router Redundancy Protocol (VRRP) feature can solve the static configuration problem. VRRP is an IP routing redundancy protocol designed to allow for transparent failover at the first-hop IP router. 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.

For example, Figure 1 shows a LAN topology in which VRRP is configured. In this example, Routers A, B, and C are VRRP routers (routers running VRRP) that compose a virtual router. The IP address of the virtual router is the same as that configured for the interface of Router A (10.0.0.1).

Figure 1. Basic VRRP Topology

Because the virtual router uses the IP address of the physical interface of Router A, Router A assumes the role of the master virtual router and is also known as the IP address owner. As the master virtual router, 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 backup virtual routers. If the master virtual router fails, the router configured with the higher priority becomes the master virtual router and provides uninterrupted service for the LAN hosts. When Router A recovers, it becomes the master virtual router again.


Note

We recommend that you disable Spanning Tree Protocol (STP) on switch ports to which the virtual routers are connected. Enable RSTP or rapid-PVST on the switch interfaces if the switch supports these protocols.

Multiple Virtual Router Support

You can configure up to 255 virtual routers on a router physical interface. The actual number of virtual routers that a router interface can support depends on the following factors:

  • 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 or more virtual routers and as a backup for one or more virtual routers.

VRRP Router Priority

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 master virtual router fails.

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

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

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

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

VRRP Advertisements

The master virtual router sends VRRP advertisements to other VRRP routers in the same group. The advertisements communicate the priority and state of the master virtual router. 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.

Benefits of VRRP

The benefits of VRRP are as follows:

  • 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—VRRP supports up to virtual routers (VRRP groups) on a router interface, subject to the platform supporting multiple MAC addresses. Multiple virtual router support enables you to implement redundancy and load sharing in your LAN topology.

  • 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 backup virtual router that has taken over for a failing master virtual router with a higher-priority backup virtual router that has become available.

  • Text Authentication—You can ensure that VRRP messages received from VRRP routers that comprise a virtual router are authenticated by configuring a simple text password.

  • 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 assigns VRRP the IP protocol number 112.

How to Implement VRRP on Cisco IOS XR Software

This section contains instructions for the following tasks:


Note

The VRRP virtual router id (vrid) has to be different for different sub-interfaces, for a given physical interface.

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 master virtual router 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.

The sections that follow describe how to customize your VRRP configuration.

SUMMARY STEPS

    1.    configure

    2.    router vrrp

    3.    interface type interface-path-id

    4.    address-family {ipv4 | ipv6}

    5.    vrrp vrid version { 2 | 3 }

    6.    text-authentication

    7.    accept-mode{disable}

    8.    priority priority

    9.    preempt [delay seconds] [disable]

    10.    timer msec interval force

    11.    track interface type instance [priority-decrement]

    12.    commit


DETAILED STEPS
     Command or ActionPurpose
    Step 1 configure
          		 
    Step 2 router vrrp


    Example: 
    
RP/0/RP0/CPU0:router(config)# router vrrp
     

    Enables VRRP configuration mode.

     
    Step 3 interface type interface-path-id


    Example: 
    
RP/0/RP0/CPU0:router(config-vrrp)# interface HundredGigE 0/2/0/1
     

    Enables VRRP interface configuration mode on a specific interface.

     
    Step 4address-family {ipv4 | ipv6}


    Example: 
    
RP/0/RP0/CPU0:routerconfig-vrrp-if)# address-family ipv6
     

    Enters the IPv4 or IPv6 address family submode.

     
    Step 5vrrp vrid version { 2 | 3 }


    Example: 
    
RP/0/RP0/CPU0:router(config-vrrp-virtual-router)# vrrp 3 version 3
RP/0/RP0/CPU0:router(config-vrrp-virtual-router)#
     

    Enters the virtual router configuration submode.

    Note   

    The version keyword is available only for the ipv4 address family.

     
    Step 6 text-authentication


    Example: 
    
RP/0/RP0/CPU0:router(config-vrrp-virtual-router)# text-authentication
     

    (Optional) Configures the simple text authentication used for Virtual Router Redundancy Protocol (VRRP) packets received from other routers running VRRP.

    • When a VRRP packet arrives from another router in the VRRP group, its authentication string is compared to the string configured on the local system. If the strings match, the message is accepted. If they do not match, the packet is discarded.

    • All routers within the group must be configured with the same authentication string.

    • To disable VRRP authentication, use the no command.

    Note   

    Plain text authentication is not meant to be used for security. It simply provides a way to prevent a misconfigured router from participating in VRRP.

     
    Step 7 accept-mode{disable}


    Example: 
    
RP/0/RP0/CPU0:router# (config-vrrp-virtual-router)# accept-mode disable
     

    Enters the IPv4 or IPv6 address family submode.

     
    Step 8 priority priority


    Example: 
    
RP/0/RP0/CPU0:router# (config-vrrp-virtual-router)# priority 254
     

    (Optional) Sets the priority of the virtual router.

    • Use the priority command to control which router becomes the master router.

    • The priority command is ignored while the router is the virtual IP address owner.

    • To remove the priority of the virtual router, use the no priority command.

     
    Step 9 preempt [delay seconds] [disable]


    Example: 
    
RP/0/RP0/CPU0:router# (config-vrrp-virtual-router)# preempt delay 15
     

    (Optional) Sets the the virtual router.

    • Use the preempt command to control which router becomes the master router.

    • The preempt command is ignored while the router is the virtual IP address owner.

    • disable preemption, use the no preempt command.

     
    Step 10 timer msec interval force


    Example: 
    
RP/0/RP0/CPU0:router# (config-vrrp-virtual-router)# timer 4
     

    (Optional) Configures the interval between successive advertisements by the master router in a virtual router.

    • To restore the default value, use the no timer command.

    Note   

    We recommend configuring the same VRRPv3 timers on all VRRP routers when interoperating with other vendors.

     
    Step 11 track interface type instance [priority-decrement]


    Example: 
    
RP/0/RP0/CPU0:router# (config-vrrp-virtual-router)# track interface HundredGigE 0/0/CPU0/1 30
     

    (Optional) Configures the to track an interface.

    • Enter the no track interface type instance interface-path-id [priority-decrement] command to disable tracking.

    • Only IP interfaces are tracked.

    • A tracked interface is up if IP on that interface is up. Otherwise, the tracked interface is down.

    • You can configure VRRP to track an interface that can alter the priority level of a virtual router for a VRRP virtual router. When the IP protocol state of an interface goes down or the interface has been removed from the router, the priority of the backup virtual router is decremented by the value specified in the priority-decrement argument. When the IP protocol state on the interface returns to the up state, the priority is restored.

     
    Step 12 commit
          		 

    Enabling VRRP

    Use the address command to enable VRRP on an interface, as described in the sections that follow.

    SUMMARY STEPS

      1.    configure

      2.    router vrrp

      3.    interface type interface-path-id

      4.    address-family ipv4

      5.    vrrp vrid version { 2 | 3 }

      6.    address address

      7.    commit


    DETAILED STEPS
       Command or ActionPurpose
      Step 1 configure
              		 
      Step 2 router vrrp


      Example: 
      
RP/0/RP0/CPU0:router(config)# router vrrp
       

      Enables VRRP configuration mode.

       
      Step 3 interface type interface-path-id


      Example: 
      
RP/0/RP0/CPU0:router(config-vrrp)# interface HundredGigE 0/2/0/1
RP/0/RP0/CPU0:router(config-vrrp-if)#
       

      Enables VRRP interface configuration mode on a specific interface.

       
      Step 4address-family ipv4


      Example: 
      
RP/0/RP0/CPU0:routerconfig-vrrp-if)# address-family ipv4
       

      Enters the IPv4 or IPv6 address family submode.

       
      Step 5vrrp vrid version { 2 | 3 }


      Example: 
      
RP/0/RP0/CPU0:router(config-vrrp-virtual-router)# vrrp 3 version 3
RP/0/RP0/CPU0:router(config-vrrp-virtual-router)#
       

      Enters the virtual router configuration submode.

      Note   

      The version keyword is available only for the ipv4 address family.

       
      Step 6 address address


      Example: 
      
RP/0/RP0/CPU0:router(config-vrrp-virtual-router)# address 2001:db8::/32
       

      Enables the Virtual Router Redundancy Protocol (VRRP) on an interface and specifies the IP address of the virtual router.

      • We recommend that you do not remove the VRRP configuration from the IP address owner and leave the IP address of the interface active, because duplicate IP addresses on the LAN will result.

      • To disable VRRP on the interface and remove the IP address of the virtual router, use the no address address command.

       
      Step 7 commit
              		 

      Verifying VRRP

      Use the show vrrp command to display a brief or detailed status of one or all VRRP virtual routers.

      SUMMARY STEPS

        1.    show vrrp [ ipv4 | ipv6 ] [ interface type instance interface-path-id [vrid]] [brief | detail | statistics [all]]


      DETAILED STEPS
         Command or ActionPurpose
        Step 1 show vrrp [ ipv4 | ipv6 ] [ interface type instance interface-path-id [vrid]] [brief | detail | statistics [all]]


        Example: 
        
RP/0/RP0/CPU0:router # show vrrp
         

        Displays a brief or detailed status of one or all Virtual Router Redundancy Protocol (VRRP) virtual routers.

        • If no interface is specified, all virtual routers are displayed.

         

        Clearing VRRP Statistics

        Use the clear vrrp statistics command to clear all the software counters for the specified virtual router.

        SUMMARY STEPS

          1.    clear vrrp statistics [ ipv4 | ipv6 ] [interfacetype interface-path-id [vrid]]


        DETAILED STEPS
           Command or ActionPurpose
          Step 1 clear vrrp statistics [ ipv4 | ipv6 ] [interfacetype interface-path-id [vrid]]


          Example: 
          
RP/0/RP0/CPU0:router# clear vrrp statistics
           

          Clears all software counters for the specified virtual router.

          • If no interface is specified, statistics of all virtual routers are removed.

           

          Configuration Examples for VRRP Implementation on Cisco IOS XR Software

          This section provides the following VRRP configuration examples:

          Configuring accept-mode

          Perform this task to disable the installation of routes for the VRRP virtual addresses.

          SUMMARY STEPS

            1.    configure

            2.    router vrrp

            3.    interface type interface-path-id

            4.    address-family {ipv4 | ipv6}

            5.    vrrp vrid version { 2 | 3 }

            6.    accept-mode disable

            7.    commit


          DETAILED STEPS
             Command or ActionPurpose
            Step 1 configure
                          		 
            Step 2router vrrp


            Example: 
            
RP/0/RP0/CPU0:router(config)# router vrrp
             

            Enables the VRRP configuration mode.

             
            Step 3interface type interface-path-id


            Example: 
            
RP/0/RP0/CPU0:router(config-vrrp)# interface HundredGigE 0/2/0/1
RP/0/RP0/CPU0:router
             

            Enables the VRRP interface configuration mode on a specific interface.

             
            Step 4address-family {ipv4 | ipv6}


            Example: 
            
RP/0/RP0/CPU0:routerconfig-vrrp-if)# address-family ipv6
RP/0/RP0/CPU0:router(config-vrrp-virtual-router)#
             

            Enters the IPv4 or IPv6 address family submode.

             
            Step 5vrrp vrid version { 2 | 3 }


            Example: 
            
RP/0/RP0/CPU0:router(config-vrrp-virtual-router)# vrrp 3 version 3
RP/0/RP0/CPU0:router(config-vrrp-virtual-router)#
             

            Enters the virtual router configuration submode.

            Note   

            The version keyword is available only for the ipv4 address family.

             
            Step 6accept-mode disable


            Example: 
            
RP/0/RP0/CPU0:router(config-vrrp-virtual-router)# accept-mode disable
             

            Disables the installation of routes for the VRRP virtual addresses.

             
            Step 7 commit
                          		 

            Configuring a Global Virtual IPv6 Address

            Perform this task to configure the global virtual IPv6 address for a virtual router.

            SUMMARY STEPS

              1.    configure

              2.    router vrrp

              3.    interface type interface-path-id

              4.    address-family ipv6

              5.    vrrp vrid version 3

              6.    address global address

              7.    commit


            DETAILED STEPS
               Command or ActionPurpose
              Step 1 configure
                              		 
              Step 2router vrrp


              Example: 
              
RP/0/RP0/CPU0:router(config)# router vrrp
               

              Enables the VRRP configuration mode.

               
              Step 3interface type interface-path-id


              Example: 
              
RP/0/RP0/CPU0:router(config-vrrp)# interface HundredGigE 0/2/0/1
               

              Enables the VRRP interface configuration mode on a specific interface.

               
              Step 4address-family ipv6


              Example: 
              
RP/0/RP0/CPU0:routerconfig-vrrp-if)# address-family ipv6
               

              Enters the IPv4 or IPv6 address family submode.

               
              Step 5vrrp vrid version 3


              Example: 
              
RP/0/RP0/CPU0:router(config-vrrp-address-family)# vrrp 3 version 3
               

              Enters the virtual router configuration submode.

              Note   

              The version keyword is available only for the ipv4 address family.

               
              Step 6address global address


              Example: 
              
RP/0/RP0/CPU0:routerconfig-vrrp-virtual-router)# address global 2001:db8::/32
               

              Configures the global virtual IPv6 address for a virtual router.

              Note   

              VRRP packet sizes are limited by the corresponding interface's Maximum Transmission Unit (MTU). This limits the maximum number of global virtual IPv6 addresses that can be supported in a single VRRP session. For example, the default MTU on gigabitEthernet interfaces would allow for a maximum of 90 VRRP global virtual IPv6 addresses in a single session. In order to have more such addresses, you need to increase the interface's MTU accordingly.

               
              Step 7 commit
                              		 

              Configuring a Primary Virtual IPv4 Address

              Perform this task to configure the primary virtual IPv4 address for a virtual router.

              SUMMARY STEPS

                1.    configure

                2.    router vrrp

                3.    interface type interface-path-id

                4.    address-family ipv4

                5.    vrrp vrid version { 2 | 3 }

                6.    address address

                7.    commit


              DETAILED STEPS
                 Command or ActionPurpose
                Step 1 configure
                                  		 
                Step 2router vrrp


                Example: 
                
RP/0/RP0/CPU0:router(config)# router vrrp
                 

                Enables the VRRP configuration mode.

                 
                Step 3interface type interface-path-id


                Example: 
                
RP/0/RP0/CPU0:router(config-vrrp)# interface HundredGigE 0/2/0/1
RP/0/RP0/CPU0:router
                 

                Enables the VRRP interface configuration mode on a specific interface.

                 
                Step 4address-family ipv4


                Example: 
                
RP/0/RP0/CPU0:routerconfig-vrrp-if)# address-family ipv4
RP/0/RP0/CPU0:router(config-vrrp-address-family)#
                 

                Enters the IPv4 address family submode.

                 
                Step 5vrrp vrid version { 2 | 3 }


                Example: 
                
RP/0/RP0/CPU0:router(config-vrrp-address-family)# vrrp 3 version 2
RP/0/RP0/CPU0:router(config-vrrp-virtual-router)
                 

                Enters the virtual router configuration submode.

                Note   

                The version keyword is available only for the ipv4 address family.

                 
                Step 6address address


                Example: 
                
RP/0/RP0/CPU0:router(config-vrrp-virtual-router)# address 10.20.30.1
                 

                Configures the primary virtual IPv4 address for a virtual router.

                 
                Step 7 commit
                                  		 

                Configuring a Secondary Virtual IPv4 Address

                Perform this task to configure the secondary virtual IPv4 address for a virtual router.

                SUMMARY STEPS

                  1.    configure

                  2.    router vrrp

                  3.    interface type interface-path-id

                  4.    address-family ipv4

                  5.    vrrp vrid version { 2 | 3 }

                  6.    address address secondary

                  7.    commit


                DETAILED STEPS
                   Command or ActionPurpose
                  Step 1 configure
                                      		 
                  Step 2router vrrp


                  Example: 
                  
RP/0/RP0/CPU0:router(config)# router vrrp
                   

                  Enables the VRRP configuration mode.

                   
                  Step 3interface type interface-path-id


                  Example: 
                  
RP/0/RP0/CPU0:router(config-vrrp)# interface HundredGigE 0/2/0/1
RP/0/RP0/CPU0:router
                   

                  Enables the VRRP interface configuration mode on a specific interface.

                   
                  Step 4address-family ipv4


                  Example: 
                  
RP/0/RP0/CPU0:routerconfig-vrrp-if)# address-family ipv4
RP/0/RP0/CPU0:router(config-vrrp-virtual-router)#
                   

                  Enters the IPv4 address family submode.

                   
                  Step 5vrrp vrid version { 2 | 3 }


                  Example: 
                  
RP/0/RP0/CPU0:router(config-vrrp-virtual-router)# vrrp 3 version 3
RP/0/RP0/CPU0:router(config-vrrp-virtual-router)#
                   

                  Enters the virtual router configuration submode.

                  Note   

                  The version keyword is available only for the ipv4 address family.

                   
                  Step 6address address secondary


                  Example: 
                  
RP/0/RP0/CPU0:router(config-vrrp-virtual-router)# address 10.20.30.1 secondary
                   

                  Configures the secondary virtual IPv4 address for a virtual router.

                   
                  Step 7 commit
                                      		 

                  Configuring a Virtual Link-Local IPv6 Address

                  Perform this task to either configure the virtual link-local IPv6 address for a virtual router or to specify that the virtual link-local IPv6 address should be enabled and calculated automatically from the virtual router virtual Media Access Control (MAC) address.

                  The IPv6 address space is structured differently compared to IPv4. Link-local addresses are used to identify each interface on the local network. These addresses may either be configured or determined automatically in a standard way using the link-layer (hardware) address of the interface (MAC address for Ethernet interfaces). Link-local addresses have a standard format and are valid only on the local network (they cannot be routed to, from multiple hops away).

                  Global unicast IPv6 addresses occupy a disjoint subset of the IPv6 address space from link-local addresses. They can be routed to, from multiple hops away and have an associated prefix length (between 0 and 128 bits).

                  Each VRRP virtual router has an associated virtual link-local address. This may be configured or determined automatically from the virtual router's virtual MAC address. The virtual MAC address must be unique on the local network. The virtual link-local address is analogous to an IPv4 virtual router's primary virtual IPv4 address, except that its virtual IP (VIP) state is always considered to be up, since duplicate address detection is not required for addresses whose scope is local.

                  SUMMARY STEPS

                    1.    configure

                    2.    router vrrp

                    3.    interface type interface-path-id

                    4.    address-family ipv6

                    5.    vrrp vrid version 3 address linklocal {address | autoconfigure}

                    6.    commit


                  DETAILED STEPS
                     Command or ActionPurpose
                    Step 1 configure
                                          		 
                    Step 2router vrrp


                    Example: 
                    RP/0/RP0/CPU0:router(config)# router vrrp
                     

                    Enables the VRRP configuration mode.

                     
                    Step 3interface type interface-path-id


                    Example: 
                    
RP/0/RP0/CPU0:router(config-vrrp)# interface HundredGigE 0/2/0/1
                     

                    Enables the VRRP interface configuration mode on a specific interface.

                     
                    Step 4address-family ipv6


                    Example: 
                    
RP/0/RP0/CPU0:routerconfig-vrrp-if)# address-family ipv6
                     

                    Enters the IPv6 address family submode.

                     
                    Step 5vrrp vrid version 3 address linklocal {address | autoconfigure}


                    Example: 
                    RP/0/RP0/CPU0:routerconfig-vrrp-address-family)# vrrp 1 version 3 address linklocal FE80::260:3EFF:FE11:6770
RP/0/RP0/CPU0:router(config-vrrp-virtual-router)#

RP/0/RP0/CPU0:router(config-vrrp-address-family)# vrrp 1 version 3 address linklocal autoconfigure
RP/0/RP0/CPU0:router(config-vrrp-virtual-router)#
                     

                    • Configures the virtual link-local IPv6 address for the virtual router.

                    • Specifies that the virtual link-local IPv6 address should be enabled and calculated automatically from the virtual router virtual MAC address.

                    Note   

                    • You must disable IPv6 Duplicate Address Detection (DAD) on an interface when the VRRP router's virtual link-local address is the same as the interface's link-local address. When DAD is disabled, duplicate packets are not flagged as duplicates.

                    • The version keyword is available only for the ipv4 address family.

                     
                    Step 6 commit
                                          		 

                    Disabling State Change Logging

                    Perform this task to disable the task of logging the VRRP state change events via syslog.

                    SUMMARY STEPS

                      1.    configure

                      2.    router vrrp

                      3.    message state disable

                      4.    commit


                    DETAILED STEPS
                       Command or ActionPurpose
                      Step 1 configure
                                              		 
                      Step 2router vrrp


                      Example:
                      
RP/0/RP0/CPU0:router(config)# router vrrp
                       

                      Enables the VRRP configuration mode.

                       
                      Step 3message state disable


                      Example:
                      
RP/0/RP0/CPU0:router(config-vrrp)# message state disable
RP/0/RP0/CPU0:router(config-vrrp)#
                       

                      Disables the task of logging the VRRP state change events via syslog.

                       
                      Step 4 commit
                                              		 

                      MIB support for VRRP

                      VRRP enables one or more IP addresses to be assumed by a router when a failure occurs. For example, when IP traffic from a host reaches a failed router because the failed router is the default gateway, the traffic is transparently forwarded by the VRRP router that has assumed control. VRRP does not require configuration of dynamic routing or router discovery protocols on every end host. The VRRP router controlling the IP address(es) associated with a virtual router is called the master, and forwards packets sent to these IP addresses. The election process provides dynamic fail over(standby) in the forwarding responsibility should the master become unavailable. This allows any of the virtual router IP addresses on the LAN to be used as the default first hop router by end-hosts.The advantage gained from using VRRP is a higher availability default path without requiring configuration of dynamic routing or router discovery protocols on every end-host. SNMP traps provide information of the state changes, when the virtual routers(in standby) are moved to master state or if the standby router is made master.

                      Configuring SNMP server notifications for VRRP events

                      The snmp-server traps vrrp events command enables the Simple Network Management Protocol (SNMP) server notifications (traps) for VRRP.

                      SUMMARY STEPS

                        1.    configure

                        2.    snmp-server traps vrrp events

                        3.    commit


                      DETAILED STEPS
                         Command or ActionPurpose
                        Step 1 configure
                                                  		 
                        Step 2 snmp-server traps vrrp events


                        Example: 
                        
RP/0/RP0/CPU0:router(config)snmp-server traps vrrp events
                         

                        Enables the SNMP server notifications for VRRP.

                         
                        Step 3 commit
                                                  		 

                        Hot Restartability for VRRP

                        In the event of failure of a VRRP process in one group, forced failovers in peer VRRP master router groups should be prevented. Hot restartability supports warm RP failover without incurring forced failovers to peer VRRP routers.

                        Configuration Examples for VRRP Implementation on Cisco IOS XR Software

                        This section provides the following VRRP configuration examples:

                        Configuring a VRRP Group: Example

                        This section provides the following configuration example of Router A and Router B, each belonging to three VRRP groups:

                        Router A: 

                        
config
interface HundredGigE 0/4/0/4
ipv4 address 10.1.0.1/24
exit
router vrrp
interface HundredGigE 0/4/0/4
address-family ipv4
vrrp 1 version 2
priority 120
text-authentication cisco
timer 3
address 10..0.
vrrp 5 version 2
timer 30
address 10..0.

preempt disable
address 10..0.
commit

                        Router B: 

                        
config
interface HundredGigE 0/4/0/4
ipv4 address 10.1.0.2/24
exit
router vrrp
interface HundredGigE 0/4/0/4
address-family ipv4
vrrp 1 version 2
priority 100
text-authentication cisco
timer 3
address 10..0.
vrrp 5 version 2
priority 200
timer 30
address 10..0.

preempt disable
address 10..0.
commit

                        In the configuration example, each group has the following properties:

                        • Virtual Router 1:

                          • Virtual IP address is 10. .0. .

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

                          • Advertising interval is 3 seconds.

                          • is .

                          • is enabled.

                        • Virtual Router 5:

                          • is .

                          • is .

                        • Virtual Router 100:

                          • Advertising interval is the default 1 second.

                          • Preemption is .

                          • is disabled.

                        Clearing VRRP Statistics: Example

                        The clear vrrp statistics command produces no output of its own. The command modifies the statistics given by show vrrp statistics command so that all the statistics are reset to zero.

                        The following section provides examples of the output of the show vrrp statistics command followed by the clear vrrp statistics command: 

                        
RP/0/RP0/CPU0:router# show vrrp statistics
show vrrp statistics
Invalid packets:
 Invalid checksum:              0
 Unknown/unsupported versions:  0
 Invalid vrID:                  10
 Too short:                     0
Protocol:
 Transitions to Master          6
Packets:
 Total received:                155
 Bad TTL:                       0
 Failed authentication:         0
 Unknown authentication:        0
 Conflicting authentication:    0
 Unknown Type field:            0
 Conflicting Advertise time:    0
 Conflicting Addresses:         0
 Received with zero priority:   3
 Sent with zero priority:       3
 

RP/0/RP0/CPU0:router# clear vrrp statistics
RP/0/RP0/CPU0:router

                        Additional References

                        The following sections provide references related to VRRP.

                        Related Documents

                        Related Topic

                        Document Title

                        QoS commands: complete command syntax, command modes, command history, defaults, usage guidelines, and examples

                        Quality of Service Commands on Modular Quality of Service Command Reference for Cisco NCS 6000 Series Routers

                        Class-based traffic shaping, traffic policing, low-latency queuing, and Modified Deficit Round Robin (MDRR)

                        Configuring Modular Quality of Service Congestion Management on Modular Quality of Service Configuration Guide for Cisco NCS 6000 Series Routers

                        WRED, RED, and tail drop

                        Configuring Modular QoS Congestion Avoidance on Modular Quality of Service Configuration Guide for Cisco NCS 6000 Series Routers

                        VRRP commands

                        VRRP Commands on IP Addresses and Services Command Reference for Cisco NCS 6000 Series Routers

                        Information about user groups and task IDs

                        Configuring AAA Services on System Security Configuration Guide for Cisco NCS 6000 Series Routers

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