202
Admin Status : Up State : Backup
Config Pri : 110 Running Pri : 80
Preempt Mode : Yes Delay Time : 5
Auth Type : Simple Key : hello
Virtual IP : 10.1.1.10
Master IP : 10.1.1.2
VRRP Track Information:
Track Object : 1 State : Negative Pri Reduced : 30
# Display detailed information about VRRP group 1 on Switch B when there is a fault on the link between
Switch A and Switch C.
[SwitchB-Vlan-interface2] display vrrp verbose
IPv4 Standby Information:
Run Mode : Standard
Run Method : Virtual MAC
Total number of virtual routers : 1
Interface Vlan-interface2
VRID : 1 Adver Timer : 5
Admin Status : Up State : Master
Config Pri : 100 Running Pri : 100
Preempt Mode : Yes Delay Time : 5
Auth Type : Simple Key : hello
Virtual IP : 10.1.1.10
Virtual MAC : 0000-5e00-0101
Master IP : 10.1.1.2
The output shows 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 the master. Packets from
Host A to Host B are forwarded through Switch B.
Configuring BFD for a VRRP backup to monitor the master
Network requirements
•
As shown in
, Switch A and Switch B belong to VRRP group 1, the virtual IP address of
which is 192.168.0.10.
•
The default gateway of the hosts in the LAN is 192.168.0.10. When Switch A works normally, the
hosts in the LAN access the external network through Switch A. When Switch A fails, the hosts in the
LAN access the external network through Switch B.
•
If BFD is not configured, when the master in a VRRP group fails, the backup cannot become the
master until the configured timeout timer expires. The timeout is generally three to four seconds,
which makes the switchover slow. To solve this problem, VRRP uses BFD to probe the state of the
master. Once the master fails, the backup can become the new master in milliseconds.