Solved: native vlan

twissam · ‎02-24-2008

Hi,

this must be in the switching forum, but i guess i need to know its impact with the voice setup.

I read the following:

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In 802.1Q trunking, all VLAN packets are tagged on the trunk link, except the native VLAN. The native VLAN packets are sent untagged on the trunk link. Therefore, the native VLAN must be the same on both switches configured for trunking. This makes it easy to deduce to which VLAN a frame belongs when a frame is received with no tag. By default, VLAN 1 is the native VLAN on all switches.

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the above is very clear, my questions are:

1) How can i tell what is the native vlan on the router, if none is configured (would it be 1)

2) On the switch i can have a different native vlan on each port, i am confused, isn't it a global thing.

I would appreciate if you can get me with a document detailing the native vlan and possibly have answer to my questions :-)

Good day

vmoopeung · ‎02-29-2008

When you use an IEEE 802.1Q trunk port, all frames are tagged except those on the VLAN configured as the "native VLAN" for the port. Frames on the native VLAN are always transmitted untagged and are normally received untagged. The management traffic between switchs or router are untagged and use native Vlan get across. by default Vlan 1 is the native vlan Before a port has trunking turned on, it belongs to a single VLAN. When trunking is turned on, the port can carry traffic for many VLANs. The port still remembers the VLAN it was in before trunking was turned on, which is called the native VLAN. The native VLAN is central to 802.1q trunking. If the native VLAN on each end of the link does not match, a port goes into the errDisable state.

You do not have to configure native vlan on the router if the native vlan on the switch is vlan1.

http://www.cisco.com/en/US/tech/tk389/tk815/technologies_configuration_example09186a00800949fd.shtml

View solution in original post

vmoopeung · ‎02-29-2008

When you use an IEEE 802.1Q trunk port, all frames are tagged except those on the VLAN configured as the "native VLAN" for the port. Frames on the native VLAN are always transmitted untagged and are normally received untagged. The management traffic between switchs or router are untagged and use native Vlan get across. by default Vlan 1 is the native vlan Before a port has trunking turned on, it belongs to a single VLAN. When trunking is turned on, the port can carry traffic for many VLANs. The port still remembers the VLAN it was in before trunking was turned on, which is called the native VLAN. The native VLAN is central to 802.1q trunking. If the native VLAN on each end of the link does not match, a port goes into the errDisable state.

You do not have to configure native vlan on the router if the native vlan on the switch is vlan1.

http://www.cisco.com/en/US/tech/tk389/tk815/technologies_configuration_example09186a00800949fd.shtml

twissam · ‎02-29-2008

many thanks,

it was a good helpfull info.

Good day