DELL N3000 User Manual

Configuring VRRP

be configured. A given port may appear as more than one virtual router to the 

network, also, more than one port on a switch may be configured as a virtual 

router.
With VRRP, a virtual router is associated with one or more IP addresses that 

serve as default gateways. In the event that the VRRP router controlling these 

IP addresses (formally known as the master) fails, the group of IP addresses 

and the default forwarding role is taken over by a Backup VRRP router.

The VRRP router priority is a value from 1–255 that determines which router 

is the master. The greater the number, the higher the priority. If the virtual IP 

address is the IP address of a VLAN routing interface on one of the routers in 

the VRRP group, the router with IP address that is the same as the virtual IP 

address is the interface owner and automatically has a priority of 255. By 

default, this router is the VRRP master in the group.
If no router in the group owns the VRRP virtual IP address, the router with 

the highest configured priority is the VRRP master. If multiple routers have 

the same priority, the router with the highest IP address becomes the VRRP 

master.
If the VRRP master fails, other members of the VRRP group will elect a 

master based on the configured router priority values. For example, router A is 

the interface owner and master, and it has a priority of 255. Router B is 

configured with a priority of 200, and Router C is configured with a priority of 

190. If Router A fails, Router B assumes the role of VRRP master because it 

has a higher priority.

If preempt mode is enabled and a router with a higher priority joins the VRRP 

group, it takes over the VRRP master role if the current VRRP master is not 

the owner of the virtual IP address. The preemption delay controls how long 

to wait to determine whether a higher priority Backup router preempts a 

lower priority master. In certain cases, for example, during periods of network 

congestion, a backup router might fail to receive advertisements from the 

master. This could cause members in the VRRP group to change their states 

frequently, i.e. flap. The problem can be resolved by setting the VRRP 

preemption delay timer to a non-zero value.