Configuring A Layer 2 Switching Port As A Trunk - Cisco 6500 Series Software Configuration Manual

Configuring LAN Interfaces for Layer 2 Switching
When using the switchport command, if a port configured for Layer 3 is now configured for Layer 2,
Note
the configuration for Layer 3 is retained in the memory but not in the running configuration and is
applied to the port whenever the port switches back to Layer 3. Also, if a port configured for Layer 2 is
now configured for Layer 3, the configuration for Layer 2 is retained in the memory but not in the
running configuration and is applied to the port whenever the port switches back to Layer 2. To restore
the default configuration of the port in the memory and in the running configuration, use the default
interface command. To avoid potential issues while changing the role of a port using the switchport
command, shut down the interface before applying the switchport command.

Configuring a Layer 2 Switching Port as a Trunk

These sections describe configuring a Layer 2 switching port as a trunk:
•
•
•
•
•
•
•
•
•
•
•
Preparing a Layer 2 Switching Port for Configuration as a Trunk
To prepare a Layer 2 switching port for configuration as a trunk, perform this task:
Command
Step 1
Router(config)# interface type
Step 2
Router(config-if)# shutdown
Step 3
Router(config-if)# switchport
1. type = ethernet, fastethernet, gigabitethernet, or tengigabitethernet
Catalyst 6500 Series Switch Cisco IOS Software Configuration Guide—Release 12.1 E
7-8
Preparing a Layer 2 Switching Port for Configuration as a Trunk, page 7-8
Configuring the Layer 2 Switching Port as an ISL or 802.1Q Trunk, page 7-9
Configuring the Layer 2 Trunk to Use DTP, page 7-9
Configuring the Layer 2 Trunk Not to Use DTP, page 7-10
Configuring the Default VLAN, page 7-10
Configuring the 802.1Q Native VLAN, page 7-11
Configuring the List of VLANs Allowed on a Trunk, page 7-11
Configuring the List of Prune-Eligible VLANs, page 7-12
Completing Trunk Configuration, page 7-13
Verifying Layer 2 Trunk Configuration, page 7-13
Configuration and Verification Examples, page 7-13
1
slot/port
Chapter 7 Configuring LAN Ports for Layer 2 Switching
Purpose
Selects the LAN port to configure.
(Optional) Shuts down the interface to prevent traffic flow
until configuration is complete.
(Optional) Configures the LAN port for Layer 2
switching (required only if the LAN port is not already
configured for Layer 2 switching; see the
LAN Port for Layer 2 Switching" section on page
"Configuring a
7-7).
78-14099-04