1-2Virtual Router Redundancy Protocol (VRRP) is designed to address this problem. VRRP adds routersthat can act as network gateways to a VRRP group, which forms a virtual router. Routers in the VRRPgroup elect a master through the VRRP election mechanism to take the responsibility of a gateway, andhosts on a LAN only need to configure the virtual router as their default network gateway.VRRP is an error-tolerant protocol, which improves the network reliability and simplifies configurationson hosts. Deploying VRRP on multicast and broadcast LANs such as Ethernet, you can ensure that thesystem can still provide highly reliable default links without changing configurations (such as dynamicrouting protocols, route discovery protocols) when a device fails, and prevent network interruption dueto failure of a single link.The S5810 series Switches support VRRPv2 that works in Standard protocol mode based on RFCs.VRRPv2 is based on IPv4.VRRP Standard Protocol ModeIntroduction to VRRP GroupVRRP combines a group of routers (including a master and multiple backups) on a LAN into a virtualrouter called VRRP group.A VRRP group has the following features:z A virtual router has an IP address. A host on the LAN only needs to know the IP address of thevirtual router and uses the IP address as the next hop of the default route.z Every host on the LAN communicates with external networks through the virtual router.z Routers in the VRRP group elect the master acting as the gateway according to their priorities. Theother routers function as the backups. When the master fails, to ensure that the hosts in thenetwork segment can communicate with the external networks uninterruptedly, the backups in theVRRP group elect a new gateway to undertake the responsibility of the failed master.Figure 1-2 Network diagram for VRRPHost AHost BHost CRouter ARouter BRouter CVirtual routerNetworkAs shown in Figure 1-2, Router A, Router B, and Router C form a virtual router, which has its own IPaddress. Hosts on the Ethernet use the virtual router as the default gateway.The router with the highest priority of the three routers is elected as the master to act as the gateway,and the other two are backups.
