Configuring BFD for RIP (bidirectional detection in BFD control packet mode)

As shown in Figure 15, VLAN-interface 100 of Switch A and VLAN-interface 200 of Switch C run RIP process 1.

VLAN-interface 300 of Switch A runs RIP process 2. VLAN-interface 400 of Switch C, and VLAN-interface 300 and VLAN-interface 400 of Switch D run RIP process 1.

• Configure a static route destined for 100.1.1.0/24 on Switch A.

• Configure a static route destined for 101.1.1.0/24 on Switch C.

• Enable static route redistribution into RIP on Switch A and Switch C. This allows Switch A to learn two routes destined for 100.1.1.0/24 through VLAN-interface 100 and VLAN-interface 300. It uses the route through VLAN-interface 100.

• Enable BFD on VLAN-interface 100 of Switch A and VLAN-interface 200 of Switch C.

When the link over VLAN-interface 100 fails, BFD can quickly detect the link failure and notify RIP. RIP deletes the neighbor relationship and the route information received learned on VLAN-interface 100. It uses the route destined for 100.1.1.0/24 through VLAN-interface 300.

1. Configure IP addresses for interfaces. (Details not shown.)

2. Configure basic RIP and enable static route redistribution into RIP so Switch A and Switch C have routes to send to each other:

   # Configure Switch A.

   <SwitchA> system-view
   [SwitchA] rip 1
   [SwitchA-rip-1] version 2
   [SwitchA-rip-1] undo summary
   [SwitchA-rip-1] network 192.168.1.0
   [SwitchA-rip-1] network 101.1.1.0
   [SwitchA-rip-1] peer 192.168.2.2
   [SwitchA-rip-1] undo validate-source-address
   [SwitchA-rip-1] import-route static
   [SwitchA-rip-1] quit
   [SwitchA] interface vlan-interface 100
   [SwitchA-Vlan-interface100] rip bfd enable
   [SwitchA-Vlan-interface100] quit
   [SwitchA] rip 2
   [SwitchA-rip-2] version 2
   [SwitchA-rip-2] undo summary
   [SwitchA-rip-2] network 192.168.3.0
   [SwitchA-rip-2] quit
   

   # Configure Switch C.

   <SwitchC> system-view
   [SwitchC] rip 1
   [SwitchC-rip-1] version 2
   [SwitchC-rip-1] undo summary
   [SwitchC-rip-1] network 192.168.2.0
   [SwitchC-rip-1] network 192.168.4.0
   [SwitchC-rip-1] network 100.1.1.0
   [SwitchC-rip-1] peer 192.168.1.1
   [SwitchC-rip-1] undo validate-source-address
   [SwitchC-rip-1] import-route static
   [SwitchC-rip-1] quit
   [SwitchC] interface vlan-interface 200
   [SwitchC-Vlan-interface200] rip bfd enable
   [SwitchC-Vlan-interface200] quit
   

   # Configure Switch D.

   <SwitchD> system-view
   [SwitchD] rip 1
   [SwitchD-rip-1] version 2
   [SwitchD-rip-1] undo summary
   [SwitchD-rip-1] network 192.168.3.0
   [SwitchD-rip-1] network 192.168.4.0
   

3. Configure BFD parameters:

   # Configure Switch A.

   [SwitchA] bfd session init-mode active
   [SwitchA] interface vlan-interface 100
   [SwitchA-Vlan-interface100] bfd min-transmit-interval 500
   [SwitchA-Vlan-interface100] bfd min-receive-interval 500
   [SwitchA-Vlan-interface100] bfd detect-multiplier 7
   [SwitchA-Vlan-interface100] quit
   

   # Configure Switch C.

   [SwitchC] bfd session init-mode active
   [SwitchC] interface vlan-interface 200
   [SwitchC-Vlan-interface200] bfd min-transmit-interval 500
   [SwitchC-Vlan-interface200] bfd min-receive-interval 500
   [SwitchC-Vlan-interface200] bfd detect-multiplier 7
   [SwitchC-Vlan-interface200] quit
   

4. Configure static routes:

   # Configure a static route to Switch C on Switch A.

   [SwitchA] ip route-static 192.168.2.0 24 vlan-interface 100 192.168.1.2
   [SwitchA] quit
   

   # Configure a static route to Switch A on Switch C.

   [SwitchC] ip route-static 192.168.1.0 24 vlan-interface 200 192.168.2.1
   

# Display the BFD session information on Switch A.

<SwitchA> display bfd session

 Total Session Num: 1     Up Session Num: 1     Init Mode: Active

 IPv4 session working under Ctrl mode:

 LD/RD             SourceAddr      DestAddr        State    Holdtime    Interface
 513/513           192.168.1.1     192.168.2.2     Up       1700ms      vlan100

# Display RIP routes destined for 100.1.1.0/24 on Switch A.

<SwitchA> display ip routing-table 100.1.1.0 24

Summary count : 1

Destination/Mask   Proto   Pre Cost        NextHop         Interface
100.1.1.0/24       RIP     100 1           192.168.2.2     vlan-interface 100

The output shows that Switch A communicates with Switch C through VLAN-interface 100. Then the link over VLAN-interface 100 fails.

# Display RIP routes destined for 100.1.1.0/24 on Switch A.

<SwitchA> display ip routing-table 100.1.1.0 24

Summary count : 1

Destination/Mask   Proto   Pre Cost        NextHop         Interface
100.1.1.0/24       RIP     100 2           192.168.3.2     vlan-interface 300

The output shows that Switch A communicates with Switch C through VLAN-interface 300.