Configuring Bfd For A Vrrp Backup To Monitor The Master - 3Com S7906E Configuration Manual

Master IP
The 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 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
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
and therefore the switchover is 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 within 1 second.
Figure 1-3 Network diagram for monitoring the master on the backup
Switch A
Master
Vlan-int2
192.168.0.101/24
Configuration procedure
1) Configure VRRP on Switch A
<SwitchA> 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 priority
of Switch A in VRRP group 1 to 110.
[SwitchA-Vlan-interface2] vrrp vrid 1 virtual-ip 192.168.0.10
: 10.1.1.2
Figure 1-3, Switch A and Switch B belong to VRRP group 1, the virtual IP address of
Internet
Virtual router
Virtual IP address:
192.168.0.10
L2 switch
Switch B
Backup
Vlan-int2
192.168.0.102/24
BFD probe packets
VRRP packets
1-11