Configuring BFD for a VRRP backup to monitor the master

As shown in Figure 36:

• Router A and Router B belong to VRRP group 1. The virtual IP address of VRRP group 1 is 192.168.0.10.

• The default gateway of the hosts in the LAN is 192.168.0.10.

Configure VRRP-Track-BFD collaboration to monitor the master on the backup and meet the following requirements:

• When Router A operates correctly, the hosts in the LAN access the Internet through Router A.

• When Router A fails, the backup (Router B) can detect the state change of the master through BFD and become the new master. The hosts in the LAN access the Internet through Router B.

1. Configure Router A:

   # Create VRRP group 1, and configure virtual IP address 192.168.0.10 for the group.

   <RouterA> system-view
   [RouterA] interface gigabitethernet 1/0/1
   [RouterA-GigabitEthernet1/0/1] vrrp vrid 1 virtual-ip 192.168.0.10
   

   # Set the priority of Router A to 110 in VRRP group 1.

   [RouterA-GigabitEthernet1/0/1] vrrp vrid 1 priority 110
   [RouterA-GigabitEthernet1/0/1] return
   

2. Configure Router B:

   # Specify 10.10.10.10 as the source address of BFD echo packets.

   <RouterB> system-view
   [RouterB] bfd echo-source-ip 10.10.10.10
   

   # Create track entry 1, and associate it with the BFD session to verify the reachability of Router A.

   [RouterB] track 1 bfd echo interface gigabitethernet 1/0/1 remote ip 192.168.0.101 local ip 192.168.0.102
   [RouterB-track-1] quit
   

   # Create VRRP group 1, and configure virtual IP address 192.168.0.10 for the group.

   [RouterB] interface gigabitethernet 1/0/1
   [RouterB-GigabitEthernet1/0/1] vrrp vrid 1 virtual-ip 192.168.0.10
   

   # Configure VRRP group 1 to monitor the status of track entry 1.

   [RouterB-GigabitEthernet1/0/1] vrrp vrid 1 track 1 switchover
   [RouterB-GigabitEthernet1/0/1] return
   

# Display detailed information about VRRP group 1 on Router A.

<RouterA> display vrrp verbose
IPv4 Virtual Router Information:
 Running Mode      : Standard
 Total number of virtual routers : 1
   Interface GigabitEthernet1/0/1
     VRID           : 1               Adver Timer  : 100
     Admin Status   : Up              State        : Master
     Config Pri     : 110             Running Pri  : 110
     Preempt Mode   : Yes             Delay Time   : 0
     Auth Type      : None
     Virtual IP     : 192.168.0.10
     Virtual MAC    : 0000-5e00-0101
     Master IP      : 192.168.0.101

# Display detailed information about VRRP group 1 on Router B.

<RouterB> display vrrp verbose
IPv4 Virtual Router Information:
 Running Mode       : Standard
 Total number of virtual routers : 1
   Interface GigabitEthernet1/0/1
     VRID           : 1               Adver Timer  : 100
     Admin Status   : Up              State        : Backup
     Config Pri     : 100             Running Pri  : 100
     Preempt Mode   : Yes             Delay Time   : 0
     Become Master  : 2200ms left
     Auth Type      : None
     Virtual IP     : 192.168.0.10
     Master IP      : 192.168.0.101
   VRRP Track Information:
     Track Object   : 1              State : Positive          Switchover

# Display information about track entry 1 on Router B.

<RouterB> display track 1
Track ID: 1
  State: Positive
  Duration: 0 days 0 hours 0 minutes 32 seconds
  Tracked object type: BFD
  Notification delay: Positive 0, Negative 0 (in seconds)
  Tracked object:
    BFD session mode: Echo
    Outgoing Interface: GigabitEthernet1/0/1
    VPN instance name: --
    Remote IP: 192.168.0.101
    Local IP: 192.168.0.102

The output shows that when the status of the track entry becomes Positive, Router A is the master, and Router B the backup.

# Enable VRRP state debugging and BFD event notification debugging on Router B.

<RouterB> terminal debugging
<RouterB> terminal monitor
<RouterB> debugging vrrp fsm
<RouterB> debugging bfd ntfy

# When Router A fails, the following output is displayed on Router B.

*Dec 17 14:44:34:142 2008 RouterB BFD/7/DEBUG: Notify application:TRACK State:DOWN
*Dec 17 14:44:34:144 2008 RouterB VRRP4/7/FSM
 IPv4 GigabitEthernet1/0/1 | Virtual Router 1 : Backup --> Master   reason: The status of the tracked object changed

# Display detailed information about the VRRP group on Router B.

<RouterB> display vrrp verbose
IPv4 Virtual Router Information:
 Running Mode      : Standard
 Total number of virtual routers : 1
   Interface GigabitEthernet1/0/1
     VRID           : 1               Adver Timer  : 100
     Admin Status   : Up              State        : Master
     Config Pri     : 100             Running Pri  : 100
     Preempt Mode   : Yes             Delay Time   : 0
     Auth Type      : None
     Virtual IP     : 192.168.0.10
     Virtual MAC    : 0000-5e00-0101
     Master IP      : 192.168.0.102
   VRRP Track Information:
     Track Object   : 1                    State : Negative   Switchover

The output shows that when BFD detects that Router A fails, the Track module notifies VRRP to change the status of Router B to master. The backup can quickly preempt as the master without waiting for a period three times the advertisement interval plus the Skew_Time.