VRRP Configuration

VRRP is configured on a per-interface basis from within config-interface mode. To define a new VR address, use ip vrrp-virtual-router <vrid> for IPv4 or ipv6 vrrp-virtual-router <vrid> for IPv6 when configuring an interface.

The <vrid> must be an integer from 1-255. This identifier must be identical for all nodes in the same cluster using a specific VR address. The VR ID must also be different from VR IDs used for other VR addresses on any other VRRP router on the network segment connected to this interface.

Note

The VR ID must only be unique on a single layer 2 network segment. The same VR ID may be used on different segments.

Note

In situations where it is unclear whether or not there is other VRRP traffic on a segment, run packet captures looking for VRRP to see if any turns up. There would typically be at least one VRRP advertisement per second from other nodes on the network. A packet capture would also show which VR IDs are active on the segment and thus should be avoided.

Tip

Though it is common to use the last octet of the VR address as the VR ID, this is not required.

Example which creates a new virtual router address:

tnsr(config)# int TenGigabitEthernet6/0/0
tnsr(config-interface)# ip vrrp-virtual-router 220
tnsr(config-vrrp4)#

This command enters config-vrrp4 (IPv4) or config-vrrp6 (IPv6) mode to configure the properties of the VR address. This mode includes the following commands:

virtual-address <ip-address>

The IPv4 or IPv6 address which will be shared by the virtual router. Also referred to as the “Virtual Router Address” or “VR Address”.

For the primary node, or owner, for this address (priority 255), the same IP address must be configured on an interface.

accept-mode (true|false)

Controls whether TNSR will accept packets delivered to this virtual address while in master state if it is not the IP address owner. The default is ‘false’.

Deployments that rely on pinging the virtual address or using it for services such as DNS or IPsec should enable this feature.

Note

IPv6 Neighbor Solicitations and Neighbor Advertisements MUST NOT be dropped when accept-mode is ‘false’.

preempt (true|false)

Instructs TNSR whether or not to preempt a lower priority peer to become master. The default value is true, and the owner of a VR address will always preempt other nodes, no matter how this value is set. When set to false, a failed node will not take back over from the current mater when it recovers, but would wait until a new election occurs.

priority <priority>

The priority for the VR address on this host. Higher values are preferred during the master election process, with the highest priority router currently operating winning the election.

The primary node, which is the owner of the VR address, must use a priority of 255 and no other node should have that priority. Lower priority nodes should use unique priority values, evenly distributed throughout the 1-254 range, depending on the number of nodes. The default value is 100.

v3-advertisement-interval <interval>

The interval, specified in centiseconds (hundredths of a second), at which VRRP advertisements will be sent by this node. The default value is 100, or one second. The value may be in the range of 1-4095.