Chapter 10
Configuring LAN Ports for Layer 2 Switching
This example shows how to verify the configuration:
Router# show running-config interface fastethernet 5/6
Building configuration...
!
Current configuration:
interface FastEthernet5/6
no ip address
switchport access vlan 200
switchport mode access
end
Router# show interfaces fastethernet 5/6 switchport
Name: Fa5/6
Switchport: Enabled
Administrative Mode: static access
Operational Mode: static access
Administrative Trunking Encapsulation: negotiate
Operational Trunking Encapsulation: native
Negotiation of Trunking: Enabled
Access Mode VLAN: 200 (VLAN0200)
Trunking Native Mode VLAN: 1 (default)
Trunking VLANs Enabled: ALL
Pruning VLANs Enabled: ALL
Router#
Configuring a Custom IEEE 802.1Q EtherType Field Value
With Release 12.2(17a)SX and later releases, you can configure a custom EtherType field value on a port
to support network devices that do not use the standard 0x8100 EtherType field value on 802.1Q-tagged
or 802.1p-tagged frames.
To configure a custom value for the EtherType field, perform this task:
Command
Router(config-if)# switchport dot1q ethertype value
Router(config-if)# no switchport dot1q ethertype
When configuring a custom EtherType field value, note the following information:
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OL-4266-08
To use a custom EtherType field value, all network devices in the traffic path across the network
must support the custom EtherType field value.
You can configure a custom EtherType field value on trunk ports, access ports, and tunnel ports.
You can configure a custom EtherType field value on the member ports of an EtherChannel.
You cannot configure a custom EtherType field value on a port-channel interface.
Each port supports only one EtherType field value. A port that is configured with a custom
EtherType field value does not recognize frames that have any other EtherType field value as tagged
frames. For example, a trunk port that is configured with a custom EtherType field value does not
recognize the standard 0x8100 EtherType field value on 802.1Q-tagged frames and cannot put the
frames into the VLAN to which they belong.
Cisco 7600 Series Router Cisco IOS Software Configuration Guide, Release 12.2SX
Configuring LAN Interfaces for Layer 2 Switching
Purpose
Configures the 802.1Q EtherType field value for the port.
Reverts to the default 802.1Q EtherType field value (0x8100).
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