配置trunk

SW1

Switch>en
Switch#conf t
Enter configuration commands, one per line.  End with CNTL/Z.

Switch(config)#hostname SW1
SW1(config)#no ip domain-lo

SW1(config)#line console 0

SW1(config-line)#exec-timeout 

SW1(config-line)#exit

SW1(config)#vlan 

SW1(config-vlan)#name caiwu

SW1(config-vlan)#vlan 

SW1(config-vlan)#name it

SW1(config-vlan)#exit

SW1(config)#interface range fastEthernet /-

SW1(config-if-range)#switchport mode access 

SW1(config-if-range)#switchport access vlan
SW1(config-if-range)#exit

SW1(config)#interface range fa0/-

SW1(config-if-range)#switchport mode access 

SW1(config-if-range)#switchport access vlan
SW1(config-if-range)#end
SW1#
%SYS--CONFIG_I: Configured from console by console

SW1#show vlan b
SW1#show vlan brief 

VLAN Name                             Status    Ports
---- -------------------------------- --------- -------------------------------
    default                          active    Fa0/, Fa0/, Fa0/, Fa0/
                                                Fa0/, Fa0/, Fa0/, Fa0/
                                                Fa0/, Fa0/, Fa0/, Fa0/
                                                Fa0/, Fa0/, Fa0/, Fa0/
                                                Fa0/, Fa0/, Fa0/, Gig0/
                                                Gig0/
    caiwu                            active    Fa0/, Fa0/
    it                               active    Fa0/, Fa0/, Fa0/
 fddi-default                     active
 token-ring-default               active
 fddinet-default                  active
 trnet-default                    active
SW1#conf t
Enter configuration commands, one per line.  End with CNTL/Z.

SW1(config)#interface gigabitEthernet /
SW1(config-if)#switchport mode trunk 

SW1(config-if)#end
SW1#

#修改native VLAN为VLAN 

Switch(config)#interface gigabitEthernet /

SW1(config-if)#switchport trunk native vlan
SW1(config-if)#
%CDP--NATIVE_VLAN_MISMATCH: Native VLAN mismatch discovered on GigabitEthernet0/ (), with Switch GigabitEthernet0/ ().

SW1(config-if)

SW2

Switch>en
Switch#conf t
Enter configuration commands, one per line.  End with CNTL/Z.

Switch(config)#no ip domain-lo

Switch(config)#line console 0

Switch(config-line)#logging synchronous 

Switch(config-line)#exec-timeout
Switch(config-line)#exit

Switch(config)#vlan 

Switch(config-vlan)#name caiwu

Switch(config-vlan)#vlan 

Switch(config-vlan)#name it

Switch(config-vlan)#exit

Switch(config)#interface fa0/

Switch(config-if)#switchport mode access 

Switch(config-if)#switchport access vlan 

Switch(config-if)#int fa0/

Switch(config-if)#switchport mode access 

Switch(config-if)#switchport access vlan
Switch(config-if)#end

Switch#
%SYS--CONFIG_I: Configured from console by console

Switch#show vlan brief 

VLAN Name                             Status    Ports
---- -------------------------------- --------- -------------------------------
    default                          active    Fa0/, Fa0/, Fa0/, Fa0/
                                                Fa0/, Fa0/, Fa0/, Fa0/
                                                Fa0/, Fa0/, Fa0/, Fa0/
                                                Fa0/, Fa0/, Fa0/, Fa0/
                                                Fa0/, Fa0/, Fa0/, Fa0/
                                                Fa0/, Fa0/, Gig0/, Gig0/
    caiwu                            active    Fa0/
    it                               active    Fa0/
 fddi-default                     active
 token-ring-default               active
 fddinet-default                  active
 trnet-default                    active
Switch#
%LINEPROTO--UPDOWN: Line protocol on Interface GigabitEthernet0/, changed state to down

%LINEPROTO--UPDOWN: Line protocol on Interface GigabitEthernet0/, changed state to up

Switch#conf t
Enter configuration commands, one per line.  End with CNTL/Z.

Switch(config)#interface gigabitEthernet /

Switch(config-if)#switchport mode trunk 

Switch(config-if)#end

Switch#conf t
Enter configuration commands, one per line.  End with CNTL/Z.

#在trunk上移除VLAN3的流量，使得SW1、SW2的VLAN3之间不能够通信
Switch(config)#interface gigabitEthernet /
Switch(config-if)#switchport trunk allowed vlan remove 

#在trunk上允许VLAN3的流量，使得SW1、SW2的VLAN3之间能够通信
Switch(config-if)#switchport trunk allowed vlan add 

#修改native VLAN为VLAN 

Switch(config)#interface gigabitEthernet /

Switch(config-if)#switchport trunk native vlan 

Switch#show interfaces trunk
Port        Mode         Encapsulation  Status        Native vlan
Gig0/      on           .1q         trunking      

Port        Vlans allowed on trunk
Gig0/      -

Port        Vlans allowed and active in management domain
Gig0/      ,,

Port        Vlans in spanning tree forwarding state and not pruned
Gig0/      ,,