Configure Additional VRRP Parameters for an Interface

Configure VRRP to provide fast failover of a default router for IPv6 LAN hosts. VRRP supports a virtual IPv6 address shared between two or more routers that connect the common subnet to the enterprise network. VRRP for IPv6 provides a faster switchover to an alternate default router than is possible using the ND protocol.

Configure the parameters in this procedure if the default values do not meet your requirements.

Before you begin

  • Assign an IPv6 address to the interface.

  • Enable routing globally.

  • Do not configure RSMLT on the VLAN.

About this task

A switch that acts as a VRRP master does not reply to SNMP get requests to the VRRP virtual interface address. The switch will, however, respond to SNMP get requests to the physical IP address.

Procedure

  1. Enter Interface Configuration mode:

    enable

    configure terminal

    interface GigabitEthernet {slot/port[/sub-port][-slot/port[/sub-port]][,...]} or interface vlan <1–4059>

    Note

    Note

    If the platform supports channelization and the port is channelized, you must also specify the sub-port in the format slot/port/sub-port.

  2. Configure the accept mode of the master router:

    ipv6 vrrp <1-255> accept-mode enable

  3. Determine if the router overrides the holddown timer:

    ipv6 vrrp <1-255> action <none|preempt>

  4. Configure the interval between advertisement messages:

    ipv6 vrrp <1-255> adver-int <1-40>

  5. Enable the backup VRRP switch for traffic forwarding:

    ipv6 vrrp <1-255> backup-master enable

  6. Configure the IP interface on the local router:

    ipv6 vrrp <1-255> critical-ipv6-addr WORD<0-46> [critical-ipv6 enable]

  7. Configure the fast advertisement interval:

    ipv6 vrrp <1-255> fast-adv enable [fast-adv-int <200-1000>]

  8. Configure the holddown timer:

    ipv6 vrrp <1-255> holddown-timer <0-21600>

  9. Configure the priority for the VRRP router:

    ipv6 vrrp <1-255> priority <1-255>

Example

Configure the fast advertisement interval:

Switch:1(config-if)#ipv6 vrrp 12 fast-adv enable fast-adv-int 400

Configure the holddown timer:

Switch:1(config-if)#ipv6 vrrp 12 holddown-timer 30

Variable Definitions

Use the data in the following table to use the ipv6 vrrp command.

Variable

Value

<1-255>

Specifies a number that uniquely identifies a virtual router on a VRRP router. The virtual router acts as the default router for one or more assigned addresses.

accept-mode enable

Controls whether the VRRP master or backup master accepts packets (other than neighbor discovery packets) destined to the IPv6 address associated with the virtual router. The default value is disable.

action <none|preempt>

Lists options to override the holddown timer manually and force preemption:

  • none does not override the timer.

  • preempt preempts the timer.

This parameter applies only if the holddown timer is active.

adver-int <1-40>

Specifies the time interval, in seconds, between sending advertisement messages. The default is 1 second. Only the master router sends advertisements.

backup-master enable

Uses the backup VRRP switch for traffic forwarding. This option reduces the traffic on the vIST. The default is disabled.

critical-ipv6 enable

Enables or disables the use of critical IP. When disabled, the VRRP ignores the availability of the address configured as critical IP. This address must be a local address. The default is disabled.

critical-ipv6-addr WORD<0-46>

Specifies an IP interface on the local router configured so that a change in its state causes a role switch in the virtual router (for example, from master to backup) in case the interface stops responding.

fast-adv enable

Enables or disables the fast advertisement interval. When disabled, the regular advertisement interval is used. The default is disable.

fast-adv-int <200-1000>

Configures the interval between VRRP advertisement messages. You must configure the same value on all participating routers.

This unit of measure must be in multiples of 200 milliseconds. The default is 200.

holddown-timer <0-21600>

Configures the amount of time, in seconds, to wait before preempting the current VRRP master. The default is 0.

priority <1-255>

Specifies the priority value used by this VRRP router. The value 255 is reserved for the router that owns the IP addresses associated with the virtual router. The default is 100.
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