1. 配置各接口所属VLAN
[LSW1]vlan batch 12 13
[LSW1-GigabitEthernet0/0/2]port link-type trunk
[LSW1-GigabitEthernet0/0/2]port trunk allow-pass vlan 12
[LSW1-GigabitEthernet0/0/3]port link-type trunk
[LSW1-GigabitEthernet0/0/3]port trunk allow-pass vlan 13
[LSW2]vlan batch 10 12 23
[LSW2-GigabitEthernet0/0/1]port link-type trunk
[LSW2-GigabitEthernet0/0/1]port trunk allow-pass vlan 12
[LSW2-GigabitEthernet0/0/3]port link-type trunk
[LSW2-GigabitEthernet0/0/3]port trunk allow-pass vlan 23
[LSW2-GigabitEthernet0/0/2]port link-type trunk
[LSW2-GigabitEthernet0/0/2]port trunk allow-pass vlan 10
[LSW3]vlan batch 13 23
[LSW3-GigabitEthernet0/0/1]port link-type trunk
[LSW3-GigabitEthernet0/0/1]port trunk allow-pass vlan 13
[LSW3-GigabitEthernet0/0/2]port link-type trunk
[LSW3-GigabitEthernet0/0/2]port trunk allow-pass vlan 23
2. 配置各VLANIF接口的IP地址
[LSW1-Vlanif12]ip add 10.1.12.1 24
[LSW1-Vlanif13]ip add 10.1.13.1 24
[LSW2-Vlanif10]ip add 192.168.1.2 24
[LSW2-Vlanif12]ip add 10.1.12.2 24
[LSW2-Vlanif23]ip add 10.1.23.2 24
[LSW3-Vlanif13]ip add 10.1.13.3 24
[LSW3-Vlanif23]ip add 10.1.23.3 24
[LSW1]stp disable
[LSW2]stp disable
[LSW3]stp disable
3. 配置BGP基本功能，在LSW1和LSW2，LSW1和LSW3之间建立EBGP连接，LSW2和LSW3之间建立IBGP连接
[LSW1]bgp 100
[LSW1-bgp]router-id 1.1.1.1
[LSW1-bgp]peer 10.1.12.2 as-number 200
[LSW1-bgp]peer 10.1.12.2 ebgp-max-hop
[LSW1-bgp]peer 10.1.13.3 as-number 200
[LSW1-bgp]peer 10.1.13.3 ebgp-max-hop
[LSW2]bgp 200
[LSW2-bgp]router-id 2.2.2.2
[LSW2-bgp]peer 10.1.12.1 as-number 100
[LSW2-bgp]peer 10.1.12.1 ebgp-max-hop
[LSW2-bgp]peer 10.1.23.3 as-number 200
[LSW2-bgp]network 192.168.1.0 24
[LSW3]bgp 200
[LSW3-bgp]router-id 3.3.3.3
[LSW3-bgp]peer 10.1.13.1 as-number 100
[LSW3-bgp]peer 10.1.13.1 ebgp-max-hop
[LSW3-bgp]peer 10.1.23.2 as-number 200
4. 配置MED属性：通过策略配置LSW2和LSW3送给LSW1的MED值
[LSW2]route-policy 12 permit node 12
[LSW2-route-policy]apply cost 100
[LSW2-bgp]peer 10.1.12.1 route-policy 12 export
[LSW3]route-policy 13 permit node 13
[LSW3-route-policy]apply cost 150
[LSW3]bgp 200
[LSW3-bgp]peer 10.1.13.1 route-policy 13 export
可以看出，去往192.168.1.0/24的路由下一跳地址为10.1.12.2，流量在主链路LSW1、LSW2上传输
5. 配置BFD检测功能、发送和接收间隔、本地检测时间倍数
[LSW1]bfd
[LSW1]bgp 100
[LSW1-bgp]peer 10.1.12.2 bfd enable
[LSW1-bgp]peer 10.1.12.2 bfd min-tx-interval 100 min-rx-interval 100 detect-multiplier 4
[LSW2]bfd
[LSW2]bgp 200
[LSW2-bgp]peer 10.1.12.1 bfd enable
[LSW2-bgp]peer 10.1.12.1 bfd min-tx-interval 100 min-rx-interval 100 detect-multiplier 4
6. 验证配置
对LSW2的VLANIF12接口执行shutdown命令，模拟主链路故障
[LSW2-Vlanif12]shutdown
可以看出，在主链路失效后，备份链路LSW1→LSW3→LSW2生效，去往192.168.10/24的路由下一跳地址为10.1.13.3