配置如下：

实现需求：

如图所示，VLAN 30和VLAN 40报文走备份链路，其他报文走主链路。为了保证网络的可靠性，VLAN 30和VLAN 40报文走备份链路，其他报文走主链路。在主链路发生故障时，主链路报文能够快速切换到备份链路；备份链路发生故障后，VLAN 30和VLAN 40的报文能够快速切换到主链路，并且使业务中断时间控制在毫秒级。

步骤

1、配置vlan

交换机S4设置
[S4]vlan batch 10 20 30 40
[S4]int g0/0/1
[S4-GigabitEthernet0/0/1] port link-type trunk
[S4-GigabitEthernet0/0/1] port trunk allow-pass vlan 10 20 30 40
[S4-GigabitEthernet0/0/1]interface GigabitEthernet0/0/2
[S4-GigabitEthernet0/0/2] port link-type trunk
[S4-GigabitEthernet0/0/2] port trunk allow-pass vlan 10 20 30 40
[S4-GigabitEthernet0/0/2]int e0/0/1
[S4-Ethernet0/0/1]port hybrid pvid vlan 10
[S4-Ethernet0/0/1]port hybrid untagged vlan 10
[S4-Ethernet0/0/1]int e0/0/2
[S4-Ethernet0/0/2]port hybrid pvid vlan 20
[S4-Ethernet0/0/2]port hybrid untagged vlan 20
[S4-Ethernet0/0/2]int e0/0/3
[S4-Ethernet0/0/3]port hybrid pvid vlan 30
[S4-Ethernet0/0/3]port hybrid untagged vlan 30
[S4-Ethernet0/0/3]int e0/0/4
[S4-Ethernet0/0/4]port hybrid pvid vlan 40
[S4-Ethernet0/0/4]port hybrid untagged vlan 40

交换机S3设置
[S3]vlan batch 10 20 30 40
[S3]interface GigabitEthernet0/0/1
[S3-GigabitEthernet0/0/1] port link-type trunk
[S3-GigabitEthernet0/0/1] port trunk allow-pass vlan 10 20 30 40
[S3-GigabitEthernet0/0/1]interface GigabitEthernet0/0/2
[S3-GigabitEthernet0/0/2] port link-type trunk
[S3-GigabitEthernet0/0/2] port trunk allow-pass vlan 10 20 30 40

交换机S2设置同S3

交换机S1设置
[S1]vlan batch 10 20 30 40
[S1]interface GigabitEthernet0/0/1
[S1-GigabitEthernet0/0/1] port link-type trunk
[S1-GigabitEthernet0/0/1] port trunk allow-pass vlan 10 20 30 40
[S1-GigabitEthernet0/0/1]interface GigabitEthernet0/0/2
[S1-GigabitEthernet0/0/2] port link-type trunk
[S1-GigabitEthernet0/0/2] port trunk allow-pass vlan 10 20 30 40
[S1-GigabitEthernet0/0/2]int e0/0/1
[S1-Ethernet0/0/1]port hybrid pvid vlan 10
[S1-Ethernet0/0/1]port hybrid untagged vlan 10
[S1-Ethernet0/0/1]int e0/0/2
[S1-Ethernet0/0/2]port hybrid pvid vlan 40

2、创建实例将vlan30 vlan40划到instance10

[S4]stp region-configuration
[S4-mst-region]instance 10 vlan 30 40
[S4-mst-region]active region-configuration
Info: This operation may take a few seconds. Please wait for a moment…done.
[S4-mst-region]q

3、stp去能，配置smart-link

[S4]int g0/0/1
[S4-GigabitEthernet0/0/1]stp disable
[S4-GigabitEthernet0/0/1]int g0/0/2
[S4-GigabitEthernet0/0/2]stp disable
[S4-GigabitEthernet0/0/2]smart-link group 1
[S4-smlk-group1]port g0/0/1 master
[S4-smlk-group1]port g0/0/2 slave

4、配置monitor链路

[S2]monitor-link group 1
[S2-mtlk-group1]port g0/0/1 uplink
[S2-mtlk-group1]port g0/0/2 downlink
[S3]monitor-link group 1
[S3-mtlk-group1]port g0/0/1 uplink
[S3-mtlk-group1]port g0/0/2 downlink

5、负载分担，实例10走备用链路

[S4-smlk-group1]load-balance instance 10 slave

6、设置smart-link回切功能

[S4-smlk-group1]restore enable
[S4-smlk-group1]timer wtr 30

7、发送flush报文和接收flush报文

[S4-smlk-group1]flush send control-vlan 10 password simple 123
[S4-smlk-group1]smart-link enable

[S3-mtlk-group1]int g0/0/1
[S3-GigabitEthernet0/0/1]smart-link flush receive control-vlan 10 password simple 123
[S3-GigabitEthernet0/0/1]int g0/0/2
[S3-GigabitEthernet0/0/2]smart-link flush receive control-vlan 10 password simple 123

[S2-mtlk-group1]int g0/0/1
[S2-GigabitEthernet0/0/1]smart-link flush receive control-vlan 10 password simple 123
[S2-GigabitEthernet0/0/1]int g0/0/2
[S2-GigabitEthernet0/0/2]smart-link flush receive control-vlan 10 password simple 123

[S1-mtlk-group1]int g0/0/1
[S1-GigabitEthernet0/0/1]smart-link flush receive control-vlan 10 password simple 123
[S1-GigabitEthernet0/0/1]int g0/0/2
[S1-GigabitEthernet0/0/2]smart-link flush receive control-vlan 10 password simple 123