7-7
Cisco 7600 Series Router Cisco IOS Software Configuration Guide—12.1E
78-14064-04
Chapter 7 Configuring LAN Ports for Layer 2 Switching
Configuring LAN Interfaces for Layer 2 Switching
Configuring LAN Interfaces for Layer 2 Switching
These sections describe how to configure Layer 2 switching on the Cisco 7600 series routers:
• Configuring a LAN Port for Layer 2 Switching, page 7-7
• Configuring a Layer 2 Switching Port as a Trunk, page 7-8
• Configuring a LAN Interface as a Layer 2 Access Port, page 7-14
Note • Use the default interface {ethernet | fastethernet | gigabitethernet | tengigabitethernet}
slot/port command to revert an interface to its default configuration.
• With Release 12.1(11b)E and later, when you are in configuration mode you can enter EXEC
mode-level commands by entering the do keyword before the EXEC mode-level command.
Configuring a LAN Port for Layer 2 Switching
To configure a LAN port for Layer 2 switching, perform this task:
After you enter the switchport command, the default mode is switchport mode dynamic desirable. If
the neighboring port supports trunking and is configured to allow trunking, the link becomes a Layer 2
trunk when you enter the switchport command. By default, LAN trunk ports negotiate encapsulation. If
the neighboring port supports ISL and 802.1Q encapsulation and both ports are set to negotiate the
encapsulation type, the trunk uses ISL encapsulation (10-Gigabit Ethernet ports do not support ISL
encapsulation).
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
Configures the LAN port for Layer 2 switching.
Note You must enter the switchport command once
without any keywords to configure the LAN port
as a Layer 2 port before you can enter additional
switchport commands with keywords.
Router(config-if)# no switchport
Clears Layer 2 LAN port configuration.
Step 4
Router(config-if)# no shutdown
Activates the interface. (Required only if you shut down
the interface.)
Step 5
Router(config-if)# end
Exits configuration mode.
Step 6
Router# show running-config interface
[type
1
slot/port]
Displays the running configuration of the interface.
Step 7
Router# show interfaces [type
1
slot/port]
switchport
Displays the switch port configuration of the interface.
Step 8
Router# show interfaces [type
1
slot/port] trunk
Displays the trunk configuration of the interface.
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