NETGEAR M4100, M7100 manual Vrrp, Virtual Router Redundancy Protocol

9. VRRP	9
Virtual Router Redundancy Protocol

This chapter provides the following examples:

•VRRP on a Master Router on page 130

•VRRP on a Backup Router on page 132

When an end station is statically configured with the address of the router that will handle its routed traffic, a single point of failure is introduced into the network. If the router goes down, the end station is unable to communicate. Since static configuration is a convenient way to assign router addresses, Virtual Router Redundancy Protocol (VRRP) was developed to provide a backup mechanism.

Layer 3 switch	Layer 3 switch
acting as router 1	acting as router 2
Port 1/0/2	Port 1/0/4 VLAN
192.150.2.1	192.150.4.1
Virtual router ID 20	Virtual router ID 20
Virtual addr. 192.150.2.1	Virtual addr. 192.150.2.1
	Layer 2 Switch

Hosts

Figure 15. VRRP

VRRP eliminates the single point of failure associated with static default routes by enabling a backup router to take over from a master router without affecting the end stations using the route. The end stations use a virtual IP address that is recognized by the backup router if the master router fails. Participating routers use an election protocol to determine which router is the master router at any given time. A given port could appear as more than one virtual router to the network. Also, more than one port on a M4100 and M7100 Managed Switch can be configured as a virtual router. Either a physical port or a routed VLAN can participate.

Chapter 9. VRRP 129