Packet type: Echo
The output shows that when the status of the track entry becomes Positive, Switch A is the master, and
Switch B the backup.
# Enable VRRP state debugging and BFD event debugging on Switch B.
<SwitchB> terminal debugging
<SwitchB> terminal monitor
<SwitchB> debugging vrrp state
<SwitchB> debugging bfd event
# When Switch A fails, the following output is displayed on Switch B.
[Src:192.168.0.102,Dst:192.168.0.101,Vlan-interface2,Echo], instance:0, protocol:Track
*Dec 17 14:44:34:144 2008 SwitchB VRRP/7/DebugState: IPv4 Vlan-interface2 | Virtual
Router 1 : Backup --> Master
# Display the detailed information of the VRRP group on Switch B.
<SwitchB> display vrrp verbose
IPv4 Standby Information:
Total number of virtual routers : 1
VRRP Track Information:
The output shows that when BFD detects that Switch A fails, it notifies VRRP through the track module to
change the status of Switch B to master without waiting for a period three times the advertisement
interval, so that a backup can quickly preempt as the master.
Configuring BFD for the VRRP master to monitor the uplinks
As shown in
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 detects that the uplink is down through BFD, it decreases its priority so that Switch
reason: The status of the tracked object changed
: Virtual MAC
47, Switch A and Switch B belong to VRRP group 1, whose virtual IP address is
State : Negative