Configuring A Custom Ieee 802.1Q Ethertype Field Value - Cisco 6500 Series Software Configuration Manual

Configuring LAN Interfaces for Layer 2 Switching
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 12.1(20)E 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:
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A port that is configured with a custom EtherType field value considers frames that have any other
Caution
EtherType field value to be untagged frames. A trunk port with a custom EtherType field value places
frames with any other EtherType field value into the native VLAN. An access port or tunnel port with a
custom EtherType field value places frames that are tagged with any other EtherType field value into the
access VLAN. If you misconfigure a custom EtherType field value, frames might be placed into the
wrong VLAN.
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Catalyst 6500 Series Switch Cisco IOS Software Configuration Guide—Release 12.1 E
7-16
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.
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.
You can configure a custom EtherType field value on these modules:
Supervisor engines
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WS-X6516A-GBIC
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Chapter 7 Configuring LAN Ports 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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