实验四 配置primary VLAN和secondary VLAN
主附vlan一般用于一个网络段的情况，主vlan和子vlan间可以访问，而子vlan之间是不能访问的。
[SwitchA]vlan 2[SwitchA-vlan2]port ethernet 0/5 to ethernet 0/6
[SwitchA]vlan 3[SwitchA-vlan3]port ethernet 0/7 to ethernet 0/8
[SwitchA]vlan 5[SwitchA-vlan5]port ethernet 0/1 to ethernet 0/4[SwitchA-vlan5]isolate-user-vlan enable ;vlan5是主vlan[SwitchA-vlan5]quit
[SwitchA]isolate-user-vlan 5 secondary 2,3 ;vlan2,3是子vlan
[SwitchB]vlan 2[SwitchB-vlan2]port ethernet 0/5 to ethernet 0/6
[SwitchB]vlan 3[SwitchB-vlan3]port ethernet 0/7 to ethernet 0/8
[SwitchA]vlan 4[SwitchB-vlan4]port ethernet 0/1 to ethernet 0/4[SwitchB-vlan4]isolate-user-vlan enable ;vlan4是主vlan[SwitchB-vlan4]quit
[SwitchB]isolate-user-vlan 4 secondary 2,3 ;vlan2,3是子vlan
