Configuring BFD for RIP (single-hop echo detection for a directly connected neighbor)

As shown in Figure 11, VLAN-interface 100 of Switch A and Switch C runs RIP process 1. VLAN-interface 200 of Switch A runs RIP process 2. VLAN-interface 300 of Switch C and VLAN-interface 200 and VLAN-interface 300 of Switch B run RIP process 1.

Configure a static route destined for 100.1.1.1/24 and enable static route redistribution into RIP on Switch C so Switch A can learn two routes destined for 100.1.1.1/24 through VLAN-interface 100 and VLAN-interface 200 respectively, and uses the one through VLAN-interface 100.

Enable BFD for RIP on VLAN-interface 100 of Switch A. When the link over VLAN-interface 100 fails, BFD can quickly detect the failure and notify it to RIP so RIP deletes the neighbor relationship and route information learned on VLAN-interface 100, and uses the route destined for 100.1.1.1 24 through VLAN-interface 200.

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

2. Configure basic RIP:

   # 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] 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 192.168.2.0
   [SwitchA-rip-2] quit
   

   # Configure Switch B.

   <SwitchB> system-view
   [SwitchB] rip 1
   [SwitchB-rip-1] version 2
   [SwitchB-rip-1] undo summary
   [SwitchB-rip-1] network 192.168.2.0
   [SwitchB-rip-1] network 192.168.3.0
   [SwitchB-rip-1] quit
   

   # Configure Switch C.

   <SwitchC> system-view
   [SwitchC] rip 1
   [SwitchC-rip-1] version 2
   [SwitchC-rip-1] undo summary
   [SwitchC-rip-1] network 192.168.1.0
   [SwitchC-rip-1] network 192.168.3.0
   [SwitchC-rip-1] import-route static
   [SwitchC-rip-1] quit
   

3. Configure BFD parameters on VLAN-interface 100 of Switch A.

   [SwitchA] bfd session init-mode active
   [SwitchA] bfd echo-source-ip 11.11.11.11
   [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
   [SwitchA] quit
   

4. Configure a static route on Switch C.

   [SwitchC] ip route-static 120.1.1.1 24 null 0
   

# 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 Echo Mode:

 LD          SourceAddr      DestAddr        State    Holdtime    Interface
 4            192.168.1.1     192.168.1.2     Up       2000ms      Vlan100

# Display RIP routes destined for 120.1.1.0/24 on Switch A.

<SwitchA> display ip routing-table 120.1.1.0 24 verbose

Summary Count : 1

Destination: 120.1.1.0/24
   Protocol: RIP             Process ID: 1
  SubProtID: 0x1                    Age: 04h20m37s
       Cost: 1               Preference: 100
        Tag: 0                    State: Active Adv
  OrigTblID: 0x0                OrigVrf: default-vrf
    TableID: 0x2                 OrigAs: 0
      NBRID: 0x26000002          LastAs: 0
     AttrID: 0xffffffff        Neighbor: 192.168.1.2
      Flags: 0x1008c        OrigNextHop: 192.168.1.2
      Label: NULL           RealNextHop: 192.168.1.2
    BkLabel: NULL             BkNextHop: N/A
  Tunnel ID: Invalid          Interface: Vlan-interface100
BkTunnel ID: Invalid        BkInterface: N/A

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 120.1.1.0/24 on Switch A.

<SwitchA> display ip routing-table 120.1.1.0 24 verbose

Summary Count : 1

Destination: 120.1.1.0/24
   Protocol: RIP             Process ID: 2
  SubProtID: 0x1                    Age: 04h20m37s
       Cost: 1               Preference: 100
        Tag: 0                    State: Active Adv
  OrigTblID: 0x0                OrigVrf: default-vrf
    TableID: 0x2                 OrigAs: 0
      NBRID: 0x26000002          LastAs: 0
     AttrID: 0xffffffff        Neighbor: 192.168.2.2
      Flags: 0x1008c        OrigNextHop: 192.168.2.2
      Label: NULL           RealNextHop: 192.168.2.2
    BkLabel: NULL             BkNextHop: N/A
  Tunnel ID: Invalid          Interface: Vlan-interface200
BkTunnel ID: Invalid        BkInterface: N/A

The output shows that Switch A communicates with Switch C through VLAN-interface 200.