H3C Technologies H3C SR8800 - Manual (Page 131)

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VRRP Track Information:
Track Object : 1 State : Negative Pri Reduced : 30
# Display detailed information about VRRP group 1 on Router B when a fault is on the link between
Router A and Router C.
[RouterB-GigabitEthernet3/1/10] display vrrp verbose
IPv4 Standby Information:
Run Mode : Standard
Run Method : Virtual MAC
Total number of virtual routers : 1
Interface GigabitEthernet3/1/10
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 a fault is on the link between Router A and Router C, the priority of Router
A decreases to 80. Router A becomes the backup, and Router B becomes the master. Packets from Host
A to Host B are forwarded through Router B.
Configuring BFD for a vrrp backup to monitor the master
Network requirements
• As shown in Figure 34 , Router A and Router B belong to VRRP group 1, whose virtual IP address is
192.168.0.10.
• The default gateway of the hosts in the LAN is 192.168.0.10. When Router A works normally, the
hosts in the LAN access the external network through Router A. When Router A fails, the hosts in the
LAN access the external network through Router 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.