Virtual Router Redundancy Protocol VRRP settings

Virtual Router Redundancy Protocol (VRRP) is a redundancy protocol for routers. VRRP allows several routers on a subnet to use the same virtual IP address, with the physical routers representing a “virtual router.” Two or more physical routers are configured to stand for the virtual router, with only one doing the actual routing at any given time. The virtual router has a unique You can share IP address and MAC address with all routers in a VRRP group. Using a virtual router redundancy protocol allows you to configure systems with a single default gateway, rather than running an active routing protocol.

There are two roles in VRRP: master, and backup. The master represents the virtual router and forwards IP traffic. The physical router that is currently routing the data is known as the Master. If the Master router fails, another Backup router automatically replaces it. Backup routers monitor the health of the master router, and in the event that the master stops sending advertisements, backup routers stage an election to determine which one will be the next master, and take over the virtual router IP address. The time required to make the determination that the master is down and hold elections depends on configuration, but typically occurs in about 3 seconds.

You can configure a number of VRRP groups (up to 255) on a LAN. A router may participate in multiple groups. All routers must be within one hop of each other (does not route).

VRRP settings include:

• Virtual Router Identifier (VRID): The virtual router ID. All routers in the same VRID communicate with each other. Specify a VRID value between 1 and 255. All routers that are to communicate must have the same VRID.
• Priority: Determines which router is the master. The router with the highest priority is the master. The default priority is 100.
• Advertisement Interval: The amount of time in milliseconds between VRRP master advertisements. Set all routers in the virtual routing group to the same value. 3000 msec (3 seconds) is typically used.
• Enable Preempt: This settings controls whether a higher priority Backup router preempts a lower priority Master. Select the check box to enable preemption; clear the check box to prohibit preemption. The default setting is enabled.
• IP Address: The IP Address of the virtual router. All routers in the same VRID should use the same virtual IP address. Configure clients to use this value as their default gateway.