1. 配置各接口所属VLAN
[LSW1]vlan batch 10 20
[LSW1-GigabitEthernet0/0/1]port link-type trunk
[LSW1-GigabitEthernet0/0/1]port trunk allow-pass vlan 10
[LSW1-GigabitEthernet0/0/2]port link-type trunk
[LSW1-GigabitEthernet0/0/2]port trunk allow-pass vlan 20
[LSW2]vlan batch 10 30 40
[LSW2-GigabitEthernet0/0/1]port link-type trunk
[LSW2-GigabitEthernet0/0/1]port trunk allow-pass vlan 10
[LSW2-GigabitEthernet0/0/2]port link-type trunk
[LSW2-GigabitEthernet0/0/2]port trunk allow-pass vlan 30
[LSW2-GigabitEthernet0/0/3]port link-type trunk
[LSW2-GigabitEthernet0/0/3]port trunk allow-pass vlan 40
[LSW3]vlan batch 20 30
[LSW3-GigabitEthernet0/0/2]port link-type trunk
[LSW3-GigabitEthernet0/0/2]port trunk allow-pass vlan 20
[LSW3-GigabitEthernet0/0/1]port link-type trunk
[LSW3-GigabitEthernet0/0/1]port trunk allow-pass vlan 30
[LSW4]vlan 10
[LSW4-Ethernet0/0/1]port link-type trunk
[LSW4-Ethernet0/0/1]port trunk allow-pass vlan 10
[LSW4-Ethernet0/0/2]port link-type trunk
[LSW4-Ethernet0/0/2]port trunk allow-pass vlan 10
2. 配置各交换机VLANIF接口的IP地址
[LSW1-Vlanif10]ip add 10.1.1.1 24
[LSW1-Vlanif20]ip add 10.2.1.1 24
[LSW2-Vlanif10]ip add 10.1.1.2 24
[LSW2-Vlanif30]ip add 10.3.1.2 24
[LSW2-Vlanif40]ip add 10.4.1.2 24
[LSW3-Vlanif20]ip add 10.2.1.3 24
[LSW3-Vlanif30]ip add 10.3.1.3 24
3.关闭STP：在使能STP的环形网络中，如果用交换机的VLANIF接口构建三层网络，会导致某个端口被阻塞，从而导致三层业务不能正常运行
[LSW1]stp disable
[LSW2]stp disable
[LSW3]stp disable
[LSW4]stp disable
4. 配置IS-IS基本功能
[LSW1]isis
[LSW1-isis-1]is-level level-2
[LSW1-isis-1]network-entity 10.0000.0000.0001.00
[LSW1-Vlanif10]isis enable 1
[LSW1-Vlanif20]isis enable 1
[LSW2]isis
[LSW2-isis-1]is-level level-2
[LSW2-isis-1]network-entity 10.0000.0000.0002.00
[LSW2-Vlanif10]isis enable 1
[LSW2-Vlanif30]isis enable 1
[LSW2-Vlanif40]isis enable 1
[LSW3]isis
[LSW3-isis-1]is-level level-2
[LSW3-isis-1]network-entity 10.0000.0000.0003.00
[LSW3-Vlanif20]isis enable 1
[LSW3-Vlanif30]isis enable 1
可以看到去往10.4.1.0/24网段的下一跳时10.1.1.2
5. 配置接口开销值，缺省为10
[LSW1-Vlanif10]isis cost 5
[LSW2-Vlanif10]isis cost 5
6. 配置IS-IS进程的BFD特性
[LSW1]bfd
[LSW1]isis
[LSW1-isis-1]bfd all-interfaces enable
[LSW2]bfd
[LSW2]isis
[LSW2-isis-1]bfd all-interfaces enable
[LSW3]bfd
[LSW3]isis
[LSW3-isis-1]bfd all-interfaces enable
7. 配置接口的BFD特性：指定最小发送和接收间隔为100ms，本地检测时间倍数为4
[LSW1-Vlanif10]isis bfd enable
[LSW1-Vlanif10]isis bfd min-tx-interval 100 min-rx-interval 100 detect-multiplir 4
[LSW2-Vlanif10]isis bfd enable
[LSW2-Vlanif10]isis bfd min-tx-interval 100 min-rx-interval 100 detect-multiplier 4
8. 检查配置：shutdown LSW2的g0/0/1接口，模拟链路故障
[LSW2-GigabitEthernet0/0/1]shutdown
可以看出备份链路生效
可以看出只有备份链路之间的BFD生效
