1972 CHAPTER 107: VRRP C ONFIGURATIONFigure 583 LAN networkingApparently, this approach to enabling hosts on a network to communicate withexternal networks is easy to configure but it imposes a very high requirement ofperformance stability on the device acting as the gateway. A common way toimprove system reliability is to use more egress gateways, introducing the problemof routing among the multiple egresses.Virtual Router Redundancy Protocol (VRRP) is an error-tolerant protocol designedto address this problem through separating physical devices from logical devices.Deploying VRRP on multicast and broadcast LANs such as Ethernet, you canensure that the system can still provide highly reliable default links withoutchanging configurations (such as dynamic routing protocols, route discoveryprotocols) when a device fails and prevent network interruption due to a singlelink failure.There are two VRRP versions: VRRPv2 and VRRPv3. VRRPv2 is based on IPv4, whileVRRPv3 is based on IPv6. The two versions implement the same functions butprovide different commands.VRRP Standby GroupOverviewVRRP combines a group of routers (including a master and multiple backups) on aLAN into a virtual router called standby group.The VRRP standby group has the following features:■ A virtual router has an IP address. A host on the LAN only needs to know the IPaddress of the virtual router and uses the IP address as the next hop of thedefault route.■ Every host on the LAN communicates with external networks through thevirtual router.■ Routers in the standby group elect the gateway according to their priorities.Once the master router acting as the gateway fails, the other routers in thestandby group elect a new gateway to undertake the responsibility of the failedrouter, thus ensuring that the hosts in the network segment can communicatewith the external networks uninterruptedly.GatewayNetworkHost AHost BHost C
