Re: Native VLAN?

From: Nash Darukhanawalla (ndarukha@cisco.com)
Date: Thu Feb 07 2002 - 20:58:27 EST


Angelo,

A trunk port configured with 802.1Q tagging can receive both tagged and
untagged traffic. By default, the switch forwards untagged traffic with the
native VLAN configured for the port. The native VLAN is VLAN 1 by default
or is the vlan that the port was a member of before it was configured as a
trunk.

If a packet has a VLAN ID the same as the outgoing port native VLAN ID, the
packet is transmitted untagged; otherwise, the switch transmits the packet
with a dot1q tag.

"encapsulation isl 1 native" essentially configures VLAN 1 that is sending
and receiving untagged traffic on the trunk port.

We do not care about the native vlan when encapsulation is isl because all
packets are tagged. But that's not the case with dot1q encap and so native
vlan should match at both the ends of the link.

-- Nash

At 09:24 AM 2/8/2002 +0800, Angelo De Guzman wrote:
>Hi To All,
> I'm using 2948G-L3.
> interface port-channel 1.1
> encapsulation isl 1 native
> What does it mean when the native command is added? Please enlighten me on
>this matter!
>TIA,
>Angelo



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