配置BGP与BFD联动
如下图所示，R1属于AS 1，R2和R3属于AS 2，路由器R1-R2、R3建立非直连EBGP连接，R1-R2为主链路，R1-R3-R2为备份链路；
配置接口IP地址：
[r1]int g0/0/0
[r1-GigabitEthernet0/0/0]ip address 12.1.1.1 24
配置类似，不做阐述；配置BGP：
[r1]bgp 1
[r1-bgp]router-id 1.1.1.1
[r1-bgp]peer 12.1.1.2 as-number 2
[r1-bgp]peer 13.1.1.2 as-number 2
[r2]bgp 2
[r2-bgp]router-id 2.2.2.2
[r2-bgp]peer 12.1.1.1 as-number 1
[r2-bgp]peer 23.1.1.2 as-number 2
[r2-bgp]ipv4-family unicast
[r2-bgp-af-ipv4]network 2.2.2.2 255.255.255.0
[r3]bgp 2
[r3-bgp]router-id 3.3.3.3
[r3-bgp]peer 23.1.1.1 as-number 2
[r3-bgp]peer 13.1.1.1 as-number 1查看BGP路由信息：
[r1]display bgp routing-table
BGP Local router ID is 1.1.1.1
Status codes: * - valid, > - best, d - damped,
h - history, i - internal, s - suppressed, S - Stale
Origin : i - IGP, e - EGP, ? - incomplete
Total Number of Routes: 2
Network NextHop MED LocPrf PrefVal Path/Ogn
*> 2.2.2.0/24 12.1.1.2 0 0 2i
* 13.1.1.2 0 2i配置BFD功能：
[r1]bfd
[r1-bfd]quit
[r1]bgp 1
[r1-bgp]peer 12.1.1.2 bfd enable
[r1-bgp]peer 12.1.1.2 bfd min-rx-interval 100 min-tx-interval 100 detect-multiplier 4
[r2]bfd
[r2-bfd]quit
[r2-bfd]bgp 2
[r2-bgp]peer 12.1.1.1 bfd enable
[r2-bgp]peer 12.1.1.1 bfd min-rx-interval 100 min-tx-interval 100 detect-multiplier 4查看BFD会话：
[r1]display bfd session all
--------------------------------------------------------------------------------
Local Remote PeerIpAddr State Type InterfaceName
--------------------------------------------------------------------------------
8192 8192 12.1.1.2 Up D_IP_IF GigabitEthernet0/0/0
--------------------------------------------------------------------------------
Total UP/DOWN Session Number : 1/0
[r1]display bgp bfd session all
Local_Address Peer_Address LD/RD Interface
12.1.1.1 12.1.1.2 8192/8192 GigabitEthernet0/0/0
Tx-interval(ms) Rx-interval(ms) Multiplier Session-State
100 100 4 Up
Wtr-interval(m)
0