Netgear XSM4324FS Software Administration Manual Software Version 12.x - Page 165

M4300 Series and M4300-96X Fully Managed Switches Virtual Router Redundancy Protocol Concepts 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 acting as router 1 Port 1/0/2 192.150.2.1 Virtual router ID 20 Virtual addr. 192.150.2.1 Layer 3 switch acting as router 2 Port 1/0/4 VLAN 192.150.4.1 Virtual router ID 20 Virtual addr. 192.150.2.1 Layer 2 Switch Figure 20. VRRP Hosts 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 the switch can be configured as a virtual router. Either a physical port or a routed VLAN can participate. VRRP 165 Software Administration Manual