配置DTP

拓扑一  结果：NO

默认auto（被动）模式

Switch>show interfaces fastEthernet / switchPort
Name: Fa0/
Switchport: Enabled
Administrative Mode: dynamic auto
Operational Mode: static access
Administrative Trunking Encapsulation: dot1q
Operational Trunking Encapsulation: native
Negotiation of Trunking: On
Access Mode VLAN:  (default)
Trunking Native Mode VLAN:  (default)
Voice VLAN: none
Administrative private-vlan host-association: none
Administrative private-vlan mapping: none
Administrative private-vlan trunk native VLAN: none
Administrative private-vlan trunk encapsulation: dot1q
Administrative private-vlan trunk normal VLANs: none
Administrative private-vlan trunk private VLANs: none
Operational private-vlan: none
Trunking VLANs Enabled: ALL
Pruning VLANs Enabled: -
Capture Mode Disabled
Capture VLANs Allowed: ALL
Protected: false

Switch>show interfaces trunk

Switch>

拓扑二   结果：YES

修改2端主动模式（desirable）

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

Switch(config)#interface fastEthernet /

Switch(config-if)#switchport mode dynamic desirable 

Switch(config-if)#
%LINEPROTO--UPDOWN: Line protocol on Interface FastEthernet0/, changed state to up

%LINEPROTO--UPDOWN: Line protocol on Interface FastEthernet0/, changed state to down

%LINEPROTO--UPDOWN: Line protocol on Interface FastEthernet0/, changed state to up

Switch#show interfaces trunk

Port Mode Encapsulation Status Native vlan

Fa0/1 desirable n-802.1q trunking 1

Port Vlans allowed on trunk

Fa0/1 1-1005

Port Vlans allowed and active in management domain

Fa0/1 1

Port Vlans in spanning tree forwarding state and not pruned

Fa0/1 1

拓扑三  结果：YES

修改一端主动模式（desirable）

Switch>en
Switch#conf t

Switch(config)#interface fastEthernet /

Switch(config-if)#switchport mode dynamic desirable 

%LINEPROTO--UPDOWN: Line protocol on Interface FastEthernet0/, changed state to up

%LINEPROTO--UPDOWN: Line protocol on Interface FastEthernet0/, changed state to down

%LINEPROTO--UPDOWN: Line protocol on Interface FastEthernet0/, changed state to up

Switch#show interfaces trunk

Port Mode Encapsulation Status Native vlan

Fa0/1 desirable n-802.1q trunking 1

Port Vlans allowed on trunk

Fa0/1 1-1005

Port Vlans allowed and active in management domain

Fa0/1 1

Port Vlans in spanning tree forwarding state and not pruned

Fa0/1 1

拓扑四 结果：YES

修改一端 trunk

Switch>en
Switch#conf
Configuring from terminal, memory, or network [terminal]? conf t
?Must be "terminal", "memory" or "network"
Switch#conf t
Enter configuration commands, one per line.  End with CNTL/Z.

Switch(config)#interface  fastEthernet /

Switch(config-if)#switchport mode trunk 

Switch(config-if)#
%LINEPROTO--UPDOWN: Line protocol on Interface FastEthernet0/, changed state to down

%LINEPROTO--UPDOWN: Line protocol on Interface FastEthernet0/, changed state to up

Switch#show interfaces trunk
Port        Mode         Encapsulation  Status        Native vlan
Fa0/       on           .1q         trunking      

Port        Vlans allowed on trunk
Fa0/       -

Port        Vlans allowed and active in management domain
Fa0/       

Port        Vlans in spanning tree forwarding state and not pruned
Fa0/       

默认auto，修改desirable

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

Switch(config)#interface fastEthernet /

Switch(config-if)#switchport mode dynamic desirable 

Switch(config-if)#
%LINEPROTO--UPDOWN: Line protocol on Interface FastEthernet0/, changed state to up

Switch(config-if)#end
Switch#
%SYS--CONFIG_I: Configured from console by console

Switch#show interfaces  trunk
Port        Mode         Encapsulation  Status        Native vlan
Fa0/       desirable    n-.1q       trunking      

Port        Vlans allowed on trunk
Fa0/       -

Port        Vlans allowed and active in management domain
Fa0/       

Port        Vlans in spanning tree forwarding state and not 

拓扑五  结果：NO

修改一端 access

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

Switch(config)#interface fastEthernet /

Switch(config-if)#switchport mode access 

Switch(config-if)#end

%SYS--CONFIG_I: Configured from console by console
s
% Ambiguous command: "s"

Switch#show interfaces trunk 

默认auto，修改desirable

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

Switch(config)#interface fastEthernet /

Switch(config-if)#switchport mode dynamic desirable 

Switch(config-if)#
%LINEPROTO--UPDOWN: Line protocol on Interface FastEthernet0/, changed state to up

Switch(config-if)#end
Switch#
%SYS--CONFIG_I: Configured from console by console

Switch#show interfaces trunk 

拓扑六  结果：YES