Example for Configuring BFD for BGP

Procedure

1. Configure the VLAN to which each interface belongs.

   <HUAWEI> system-view
   [~HUAWEI] sysname SwitchA
   [*HUAWEI] commit
   [~SwitchA] vlan batch 10 20
   [*SwitchA] interface 10ge 1/0/1
   [*SwitchA-10GE1/0/1] port link-type trunk
   [*SwitchA-10GE1/0/1] port trunk allow-pass vlan 10
   [*SwitchA-10GE1/0/1] quit
   [*SwitchA] interface 10ge 1/0/2
   [*SwitchA-10GE1/0/2] port link-type trunk
   [*SwitchA-10GE1/0/2] port trunk allow-pass vlan 20
   [*SwitchA-10GE1/0/2] quit
   [*SwitchA] commit

   The configurations of SwitchB and SwitchC are similar to the configuration of SwitchA, and are not provided here.

2. Configure VLANIF interfaces and assign IP addresses to the VLANIF interfaces.

   [~SwitchA] interface vlanif 10
   [*SwitchA-Vlanif10] ip address 192.168.2.1 24
   [*SwitchA-Vlanif10] quit
   [*SwitchA] interface vlanif 20
   [*SwitchA-Vlanif20] ip address 192.168.1.1 24
   [*SwitchA-Vlanif20] quit
   [*SwitchA] commit

   The configurations of SwitchB and SwitchC are similar to the configuration of SwitchA, and are not provided here.

3. Configure basic BGP functions, establish EBGP connections between SwitchA and SwitchB and between SwitchA and SwitchC, and establish an IBGP connection between SwitchB and SwitchC.

   # Configure SwitchA.

   [~SwitchA] bgp 100

   [*SwitchA-bgp] router-id 172.17.1.1

   [*SwitchA-bgp] peer 192.168.1.2 as-number 200

   [*SwitchA-bgp] peer 192.168.2.2 as-number 200

   [*SwitchA-bgp] commit

   [~SwitchA-bgp] quit

   # Configure SwitchB.

   [~SwitchB] bgp 200

   [*SwitchB-bgp] router-id 172.17.2.2

   [*SwitchB-bgp] peer 192.168.1.1 as-number 100

   [*SwitchB-bgp] peer 10.1.1.2 as-number 200

   [*SwitchB-bgp] import-route direct

   [*SwitchB-bgp] commit

   [~SwitchB-bgp] quit

   # Configure SwitchC.

   [~SwitchC] bgp 200

   [*SwitchC-bgp] router-id 172.17.3.3

   [*SwitchC-bgp] peer 192.168.2.1 as-number 100

   [*SwitchC-bgp] peer 10.1.1.1 as-number 200

   [*SwitchC-bgp] commit

   [~SwitchC-bgp] quit

   # View the BGP peer status on SwitchA, finding that BGP peers have been established.

   <SwitchA> display bgp peer

    BGP local router ID : 172.17.1.1

    Local AS number : 100

    Total number of peers : 2                

    Peers in established state : 2

     Peer            V    AS  MsgRcvd  MsgSent  OutQ  Up/Down       State PrefRcv

     192.168.1.2     4   200        2        5     0 00:01:25 Established       0

     192.168.2.2     4   200        2        4     0 00:00:55 Established       0

4. Configure the MED attribute.

   # Set the MED values for the routes sent from SwitchB and SwitchC to SwitchA using a route-policy.

   # Configure SwitchB.

   [~SwitchB] route-policy 10 permit node 10

   [*SwitchB-route-policy] apply cost 100

   [*SwitchB-route-policy] commit

   [~SwitchB-route-policy] quit

   [~SwitchB] bgp 200

   [~SwitchB-bgp] peer 192.168.1.1 route-policy 10 export

   [*SwitchB-bgp] commit

   # Configure SwitchC.

   [~SwitchC] route-policy 10 permit node 10

   [*SwitchC-route-policy] apply cost 150

   [*SwitchC-route-policy] commit

   [~SwitchC-route-policy] quit

   [~SwitchC] bgp 200

   [~SwitchC-bgp] peer 192.168.2.1 route-policy 10 export

   [*SwitchC-bgp] commit

   # View all BGP routing information on SwitchA.

   <SwitchA> display bgp routing-table

    BGP Local router ID is 172.17.1.1

    Status codes: * - valid, > - best, d - damped, h - history,

                  i - internal, s - suppressed, S - Stale

    Origin      : i - IGP, e - EGP, ? - incomplete

    Total Number of Routes: 5

         Network            NextHop        MED        LocPrf    PrefVal Path/Ogn

    *>  10.1.1.0/24        192.168.2.2     150                   0      200?

    *>  172.16.1.0/24      192.168.1.2     100                   0      200i

    *                      192.168.2.2     150                   0      200i

    *>   192.168.2.0       192.168.1.2     100                   0      200?

                           192.168.2.2     150                   0      200?

   In the BGP routing table, you can view that the next-hop address of the route to 172.16.1.0/24 is 192.168.1.2, and traffic is transmitted on the primary link SwitchA→SwitchB.

5. Configure BFD, and set the interval for sending BFD packets, the interval for receiving BFD packets, and the local detection multiplier.

   # Enable BFD on SwitchA, and set the minimum intervals for sending and receiving BFD packets to 300 ms and the local detection multiplier to 5.

   [~SwitchA] bfd

   [*SwitchA-bfd] quit

   [*SwitchA] bgp 100

   [*SwitchA-bgp] peer 192.168.1.2 bfd enable

   [*SwitchA-bgp] peer 192.168.1.2 bfd min-tx-interval 300 min-rx-interval 300 detect-multiplier 5

   [*SwitchA-bgp] commit

   # Enable BFD on SwitchB, and set the minimum intervals for sending and receiving BFD packets to 300 ms and the local detection multiplier to 5.

   [~SwitchB] bfd

   [*SwitchB-bfd] quit

   [*SwitchB] bgp 200

   [*SwitchB-bgp] peer 192.168.1.1 bfd enable

   [*SwitchB-bgp] peer 192.168.1.1 bfd min-tx-interval 300 min-rx-interval 300 detect-multiplier 5

   [*SwitchB-bgp] commit

   # View all the BFD sessions set up by BGP on SwitchA.

   <SwitchA> display bgp bfd session all

   --------------------------------------------------------------------------------

     Local_Address      Peer_Address       Interface

     192.168.1.1        192.168.1.2        Vlanif20

     Tx-interval(ms)    Rx-interval(ms)    Multiplier  Session-State

     300                300                5           Up

   --------------------------------------------------------------------------------

6. Verify the configuration.

   # Run the shutdown command on 10GE1/0/2 of SwitchB to simulate a primary link fault.

   [~SwitchB] interface 10ge 1/0/2

   [~SwitchB-10GE1/0/2] shutdown

   [*SwitchB-10GE1/0/2] commit

   # View the BGP routing table of SwitchA.

   <SwitchA> display bgp routing-table

    BGP Local router ID is 172.17.1.1

    Status codes: * - valid, > - best, d - damped, h - history,

                  i - internal, s - suppressed, S - Stale

    Origin      : i - IGP, e - EGP, ? - incomplete

    Total Number of Routes: 3

         Network            NextHop        MED        LocPrf    PrefVal Path/Ogn

    *>  10.1.1.0/24         192.168.2.2    150                   0      200?

    *>  172.16.1.0/24       192.168.2.2    150                   0      200i

        192.168.2.0         192.168.2.2    150                   0      200?

   In the BGP routing table, you can view that the backup link SwitchA→SwitchC→SwitchB takes effect after the primary link fails, and the next-hop address of the route to 172.16.1.0/24 becomes 192.168.2.2.