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Catalyst 6500 Series Switch Software Configuration Guide—Release 8.7
OL-8978-04
Chapter 5 Configuring Ethernet VLAN Trunks
Configuring a Trunk Link
Note
You can use a custom 802.1Q EtherType field on trunk ports, 802.1Q access ports, and 802.1Q/802.1p
multi-VLAN access ports. Additionally, you should configure the custom EtherType value the same on both
ends of a link.
By specifying a custom EtherType field, your network can support Cisco and non-Cisco switches that
do not use the standard 0x8100 EtherType to identify 802.1Q-tagged frames. When you specify a custom
EtherType field, you can identify 802.1Q tagged frames and switch the frames to a specified VLAN. The
two bytes immediately following the EtherType are interpreted as a standard 802.1Q tag. Specify the
value of the two-byte EtherType field in hexadecimal. The
default
value is 8100.
To specify a custom 802.1Q EtherType value in the 802.1Q tag, perform this task in privileged mode:
This example shows how to set the 802.1Q EtherType to 0x1234 on port 2/1 and verify the configuration:
Console> (enable)
set port dot1q-ethertype 2/1 1234
All the group ports 2/1-2 associated with port 2/1 will be modified.
Do you want to continue (y/n) [n]?
y
Dot1q Ethertype value set to 0x1234 on ports 2/1-2.
Console> (enable)
Console> (enable)
show port dot1q-ethertype 2/1
Port Dot1q ethertype value
---- ---------------------
2/1 1234
Console> (enable)
Returning a Custom 802.1Q EtherType Field to the Standard EtherType
The
set port dot1q-ethertype
mod/port
{
value
|
default
} command is the only command that is required
to return the custom 802.1Q EtherType field to the standard EtherType field (0x8100).
To return the custom EtherType field to the default value (0x8100), perform this task in privileged mode:
Task
Command
Step 1
Specify a custom EtherType field for a port.
set port dot1q-ethertype
mod/port
{
value
|
default
}
Step 2
Verify the configuration.
show port dot1q-ethertype
[
mod
|
mod/port
]
Task
Command
Step 1
Return the EtherType field to the standard value
(0x8100) for a port.
set port dot1q-ethertype
mod/port
default
Step 2
Verify the configuration.
show port dot1q-ethertype
[
mod
|
mod/port
]