Cisco 7609 - Configuring a Layer 2 Switching Port as a Trunk

7-8
Cisco 7600 Series Router Cisco IOS Software Configuration Guide—12.1E
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Chapter 7 Configuring LAN Ports for Layer 2 Switching
Configuring LAN Interfaces for Layer 2 Switching
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, page 7-8
• Configuring the Layer 2 Switching Port as an ISL or 802.1Q Trunk, page 7-8
• Configuring the Layer 2 Trunk to Use DTP, page 7-9
• Configuring the Layer 2 Trunk Not to Use DTP, page 7-9
• 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
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:
Configuring the Layer 2 Switching Port as an ISL or 802.1Q Trunk
Note Complete the steps in the “Preparing a Layer 2 Switching Port for Configuration as a Trunk” section on
page 7-8 before performing the tasks in this section.
Command Purpose
Step 1
Router(config)# interface type
1
slot/port
1. type = ethernet, fastethernet, gigabitethernet, or tengigabitethernet
Selects the LAN port to configure.
Step 2
Router(config-if)# shutdown
(Optional) Shuts down the interface to prevent traffic flow
until configuration is complete.
Step 3
Router(config-if)# switchport
(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 “Configuring a
LAN Port for Layer 2 Switching” section on page 7-7).