VRRP Configuration Command Reference
408 Router Configuration Guide
Non-owner virtual router instances actually create a routable IP interface address that is operationally
dependent on the virtual router instance mode (master or backup). The backup command in owner
virtual router instances does not create a routable IP interface address; it simply defines the existing
parental IP interface IP addresses that are advertised by the virtual router instance.
For owner virtual router instances, the backup command defines the IP addresses that are advertised
within VRRP advertisement messages. This communicates the IP addresses that the master is
representing to backup virtual routers receiving the messages. Advertising a correct list is important.
The specified ip-addr must be equal to one of the existing parental IP interface IP addresses (primary
or secondary) or the backup command will fail.
For non-owner virtual router instances, the backup command actually creates an IP interface IP
address used for routing IP packets and communicating with the system when the access commands
are defined (ping-reply, telnet-reply, and ssh-reply). The specified ip-addr must be an IP address that
is within one of the parental IP interface local subnets created with the address or secondary
commands. If a local subnet does not exist that includes the specified ip-addr or if ip-addr is the same
IP address as the parental IP interface IP address, the backup command will fail.
The new interface IP address created with the backup command assumes the mask and parameters of
the corresponding parent IP interface IP address. The ip-addr is only active when the virtual router
instance is operating in the master state. When not operating as master, the virtual router instance acts
as if it is operationally down. It will not respond to ARP requests to ip-addr, nor will it route packets
received with its vrid derived source MAC address. A non-master virtual router instance always
silently discards packets destined to ip-addr. A single virtual router instance may only have a single
virtual router IP address from a given parental local subnet. Multiple virtual router instances can define
a virtual router IP address from the same local subnet as long as each is a different IP address.
In IPv4, up to sixteen backup ip-addr commands can be executed within the same virtual router
instance. Executing
backup multiple times with the same ip-addr results in no operation performed
and no error generated. At least one successful backup ip-addr command must be executed before the
virtual router instance can enter the operational state.
When operating as (non-owner) master, the default functionality associated with ip-addr is ARP
response to ARP requests to ip-addr, routing of packets destined to the virtual router instance source
MAC address and silently discarding packets destined to ip-addr. Enabling the non-owner-access
parameters selectively allows ping, Telnet and SSH connectivity to ip-addr when the virtual router
instance is operating as master.
The no form of the command removes the specified virtual router IP address from the virtual router
instance. For non-owner virtual router instances, this causes all routing and local access associated
with the ip-addr to cease. For owner virtual router instances, the no backup command only removes
ip-addr from the list of advertised IP addresses. If the last ip-addr is removed from the virtual router
instance, the virtual router instance will enter the operationally down state
Default no backup — No virtual router IP address is assigned.
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