[系统运维]华为设备配置IS-IS的负载分担

1. 配置各接口所属VLAN
   [LSW1]vlan batch 10 20 50
   [LSW1-GigabitEthernet0/0/1]port link-type trunk
   [LSW1-GigabitEthernet0/0/1]port trunk allow-pass vlan 50
   [LSW1-GigabitEthernet0/0/2]port link-type trunk
   [LSW1-GigabitEthernet0/0/2]port trunk allow-pass vlan 10
   [LSW1-GigabitEthernet0/0/3]port link-type trunk
   [LSW1-GigabitEthernet0/0/3]port trunk allow-pass vlan 20
   [LSW2]vlan batch 10 30
   [LSW2-GigabitEthernet0/0/1]port link-type trunk
   [LSW2-GigabitEthernet0/0/1]port trunk allow-pass vlan 10
   [LSW2-GigabitEthernet0/0/4]port link-type trunk
   [LSW2-GigabitEthernet0/0/4]port trunk allow-pass vlan 30
   [LSW3]vlan batch 20 40
   [LSW3-GigabitEthernet0/0/1]port link-type trunk
   [LSW3-GigabitEthernet0/0/1]port trunk allow-pass vlan 20
   [LSW3-GigabitEthernet0/0/4]port link-type trunk
   [LSW3-GigabitEthernet0/0/4]port trunk allow-pass vlan 40
   [LSW4]vlan batch 30 40 60
   [LSW4-GigabitEthernet0/0/2]port link-type trunk
   [LSW4-GigabitEthernet0/0/2]port trunk allow-pass vlan 20
   [LSW4-GigabitEthernet0/0/1]port link-type trunk
   [LSW4-GigabitEthernet0/0/1]port trunk allow-pass vlan 60
   [LSW4-GigabitEthernet0/0/3]port link-type trunk
   [LSW4-GigabitEthernet0/0/3]port trunk allow-pass vlan 40
2. 配置各VLANIF接口的IP地址
   [LSW1-Vlanif50]ip add 10.5.1.1 24
   [LSW1-Vlanif10]ip add 10.1.1.1 24
   [LSW1-Vlanif20]ip add 10.1.2.1 24
   [LSW2-Vlanif10]ip add 10.1.1.2 24
   [LSW2-Vlanif30]ip add 10.1.3.2 24
   [LSW3-Vlanif20]ip add 10.1.2.3 24
   [LSW3-Vlanif40]ip add 10.1.4.3 24
   [LSW4-Vlanif60]ip add 10.6.1.4 24
   [LSW4-Vlanif40]ip add 10.1.4.4 24
   [LSW4-Vlanif30]ip add 10.1.3.4 24
3. 配置IS-IS基本功能
   [LSW1]stp disable //stp会导致某个端口被阻塞，从而导致三层业务不能正常运行
   [LSW2]stp disable
   [LSW3]stp disable
   [LSW4]stp disable
   [LSW1]isis 1
   [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
   [LSW1-Vlanif50]isis enable 1
   [LSW2]isis 1
   [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
   [LSW3]isis 1
   [LSW3-isis-1]is-level level-2
   [LSW3-isis-1]network-entity 10.0000.0000.0003.00
   [LSW3-Vlanif20]isis enable 1
   [LSW3-Vlanif40]isis enable 1
   [LSW4]isis 1
   [LSW4-isis-1]is-level level-2
   [LSW4-isis-1]network-entity 10.0000.0000.0004.00
   [LSW4-Vlanif30]isis enable 1
   [LSW4-Vlanif40]isis enable 1
   [LSW4-Vlanif60]isis enable 1
4. 在LSW1配置负载分担数目为1
   [LSW1]isis 1
   [LSW1-isis-1]maximum load-balancing 1
   

当配置负载分担最大等价路由条数为1后，到达目标网段10.6.1.0的下一跳为10.1.1.2。这是由于LSW2 system ID较小，所以IS-IS优先选择下一跳为10.1.1.2为唯一最优路由
5. 在LSW1恢复负载分担路由的缺省数量
[LSW1]isis 1
[LSW1-isis-1]undo maximum load-balancing

当恢复负载分担的缺省值后，由于最大等价路由条数的缺省值为8，因此LSW1两个下一跳10.1.1.2（LSW2）和10.1.2.3（LSW3）均成为有效路由
6. 在LSW1配置等价路由优先级
[LSW1]isis
[LSW1-isis-1]nexthop 10.1.2.3 weight 1

从路由表中可以看出，当配置等价路由的优先级后，由于下一跳为10.1.2.3（LSW3）的优先级（权值为1）高于下一跳为10.1.1.2（LSW2）的优先级，所以IS-IS优先选择下一跳为10.1.2.3为唯一最优路由