Sunday, May 29, 2011

Configuring a Trunk Port


          The Enterprise Edition Software, Cisco IOS Release 11.2(8)SA6, does not support trunk negotiation via the Dynamic   Trunk Protocol (DTP), formerly known as Dynamic ISL (DISL). If you are connecting a trunk port to a Catalyst 5000 switch or other DTP device, use the non-negotiate option on the DTP-capable device to configure the switch port to not generate DTP frames.

This example shows how to configure a port as a trunk, verify the trunk configuration, and save the change to the startup configuration file:
Switch# configure terminal

Enter configuration commands, one per line.  End with CNTL/Z.
Switch(config)# interface fa0/1

Switch(config-if)# switchport mode trunk

Switch(config-if)# switchport trunk encapsulation isl

Switch(config-if)# end

Switch# show interface fa0/1 switchport

Name: Fa0/1
Switchport: Enabled

Administrative mode: trunk

Operational Mode: trunk
Administrative Trunking Encapsulation: isl

Operational Trunking Encapsulation: isl

Negotiation of Trunking: Disabled
Access Mode VLAN: 0 ((Inactive))
Trunking Native Mode VLAN: 1 (default)
Trunking VLANs Enabled: 1-3,1002-1005
Trunking VLANs Active: 1-3
Pruning VLANs Enabled: NONE
Switch# copy running-config startup-config

Building configuration...
[OK]
Switch#