1-2establishing backup links without modifying the configuration of dynamic routing protocols and routerdiscovery protocols.Introduction to VRRP GroupVRRP allows you to combine a group of LAN switches (including a master and several backups) into aVRRP group. The VRRP group functions as a virtual router, forwarding packets as a gateway.Figure 1-2 VRRP network diagramHost 1EthernetMasterNetworkHost 2 Host 3Backup10.100.10.7/24 10.100.10.9/2410.100.10.8/24Actual IP address10.100.10.2/24Actual IP address10.100.10.3/24Virtual IP address10.100.10.1/24Virtual IP address10.100.10.1/24As shown in Figure 1-2, a VRRP group has the following features:z The virtual router (the VRRP group) has its own IP address (10.100.10.1 in the above figure).z The switches within the VRRP group must have their own IP addresses (such as 10.100.10.2 forthe master and 10.100.10.3 for the backup).z Hosts in the LAN use the IP address of the virtual router (that is, 10.100.10.1) as their defaultgateway.z Hosts in the LAN only know the IP address of this virtual router, that is, 10.100.10.1, but not thespecific IP addresses 10.100.10.2 of the master and 10.100.10.3 of the backup.If the master in the VRRP group goes down, the backups in the VRRP group will reelect a master bypriority. The backup with the highest priority functions as the new master to guarantee normalcommunication between the hosts and the external networks.Priority of a switch in a VRRP groupYou can configure the priority of a switch in a VRRP group. A master is elected from theseVRRP-enabled switches by priority and the remaining switches are backups. The master in a VRRPgroup is the one currently with the highest priority.Switch priority ranges from 0 to 255 (a larger number indicates a higher switch priority). Note that only 1through 254 are available to users. Switch priorities 0 and 255 are reserved for special uses and the IPaddress owner respectively.When a switch acts as the IP address owner, its priority is always 255. That is, if there is an IP addressowner in a VRRP group, it acts as the master as long as it works properly.
