1-11Master IP : 10.1.1.2The output information indicates that when there is a fault on the link between Switch A and Switch C,the priority of Switch A decreases to 80. Switch A becomes the backup, and Switch B becomes themaster. Packets from Host A to Host B are forwarded through Switch B.Configuring BFD for a VRRP Backup to Monitor the MasterNetwork requirementsz As shown in Figure 1-3, Switch A and Switch B belong to VRRP group 1, the virtual IP address ofwhich is 192.168.0.10.z The default gateway of the hosts in the LAN is 192.168.0.10. When Switch A works normally, thehosts in the LAN access the external network through Switch A. When Switch A fails, the hosts inthe LAN access the external network through Switch B.z If BFD is not configured, when the master in a VRRP group fails, the backup cannot become themaster until the configured timeout timer expires. The timeout is generally three to four secondsand therefore the switchover is slow. To solve this problem, VRRP uses BFD to probe the state ofthe master. Once the master fails, the backup can become the new master within 1 second.Figure 1-3 Network diagram for monitoring the master on the backupInternetVirtual routerVirtual IP address:192.168.0.10Vlan-int2192.168.0.101/24Vlan-int2192.168.0.102/24Switch AMasterSwitch BBackupL2 switchVRRP packetsBFD probe packetsConfiguration procedure1) Configure VRRP on Switch A system-view[SwitchA] interface vlan-interface 2# Create VRRP group 1, and configure the virtual IP address 192.168.0.10 for the group. Set the priorityof Switch A in VRRP group 1 to 110.[SwitchA-Vlan-interface2] vrrp vrid 1 virtual-ip 192.168.0.10
