General operating rules

  • IP routing (IPv4) or IPv6 unicast-routing (IPv6) must be enabled on the router before enabling VRRP.

  • IP must be enabled on a VLAN before creating a VR instance on the VLAN.

  • VIP:
    On an owner

    The VIP configured in a VR instance must match one of the IP addresses configured in the VLAN interface on which the VR is configured.

    On a backup

    The VIP configured in a VR instance cannot be a "real" IP address configured in a VLAN interface on that router.

NOTE:

The VIP configured for one VR cannot be configured on another VR.

  • Before

    changing a router from owner to backup, or the reverse, the VIP must be removed from the configuration.

  • The priority configuration on an owner can be only 255. The priority configuration on a backup must be 254 or lower, the default being 100.

  • Advertisement intervals:

    • If a VRRP router has a different advertisement interval than a VRRP packet it receives, the router drops the packet. For this reason, the advertisement interval must be the same for the owner and all backups in the same VR.

  • A VR exists within a single VLAN interface. If the VLAN is multinetted, a separate VR can be configured within the VLAN for each subnet. A VLAN allows up to 32 VRs (16 for the 2930F switch), and the switch allows up to 2048 VRs.

  • All routers in the same VR must belong to the same network or subnet.

  • The router supports the following maximums:

    • 32 VRs (16 for the 2930F switch) per VLAN in any combination of masters and backups

    • 512 (128 for the 2930F switch) IPv4 and IPv6 VRs in combination

    • 2046 Virtual IP addresses

    • 512 (128 for the 2930F switch) VR sessions on the switch

    • 512 (128 for the 2930F switch) VRRPv2 and VRRPv3 sessions, in any mix

    • 32 (16 for the 2930F switch) IP addresses per VR

  • Each VR uses one MAC address as described under Virtual router MAC address.

  • If an IP address is deleted on a VLAN interface, one of the following occurs:

    • VR owner: If the VR uses the same IP address as a VIP, that IP address is deleted from the VR.

    • VR backup: If the VR has a VIP in the same subnet as that of the deleted IP address, that VIP will be deleted from the VR.

    If the deleted VIP was the last VIP of an active VR, the VR will be deactivated. (For more on multiple, VIPs on a VR, see Associating more than one VIP with a VR.

  • The VRRP backup router can respond to ping requests when the virtual-ip-ping feature is enabled. For more information, see Pinging the virtual IP of a backup router.