Configuring A Lan Port For Layer 2 Switching - Cisco 7604 Configuration Manual

Chapter 10 Configuring LAN Ports for Layer 2 Switching
Use the default interface {ethernet | fastethernet | gigabitethernet | tengigabitethernet} slot/port
Note
command to revert an interface to its default configuration.

Configuring a LAN Port for Layer 2 Switching

To configure a LAN port for Layer 2 switching, perform this task:
Command
Step 1
Router(config)# interface type
Step 2
Router(config-if)# shutdown
Step 3
Router(config-if)# switchport
Router(config-if)# no switchport
Step 4
Router(config-if)# no shutdown
Step 5
Router(config-if)# end
Step 6
Router# show running-config interface
1
[ type slot/port ]
Step 7
Router# show interfaces [ type
switchport
Step 8
Router# show interfaces [ type
1. type = ethernet, fastethernet, gigabitethernet, or tengigabitethernet
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).
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.
OL-4266-08
Purpose
1
Selects the LAN port to configure.
slot/port
(Optional) Shuts down the interface to prevent traffic flow
until configuration is complete.
Configures the LAN port for Layer 2 switching.
Note
Clears Layer 2 LAN port configuration.
Activates the interface. (Required only if you shut down
the interface.)
Exits configuration mode.
Displays the running configuration of the interface.
1
Displays the switch port configuration of the interface.
slot/port ]
1
slot/port ] trunk Displays the trunk configuration of the interface.
Cisco 7600 Series Router Cisco IOS Software Configuration Guide, Release 12.2SX
Configuring LAN Interfaces for Layer 2 Switching
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.
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