Solved: question on native vlan for a particular switchport

John Blakley · ‎04-30-2009

I have an access point that currently runs over vlan 1, 150, and 151. I want to change the native vlan from 1 to 149. I can do this in the ap, but my question is this:

Let's say that my switchport is g3/0/5. On switchport g3/0/5, the config looks like:

int g3/0/5

switchport mode trunk

switchport trunk allowed vlan add 1,150,151

If I want to change my default native, I would want to do:

int g3/0/5

switchport trunk native vlan 149

Will this affect any trunks between switches that are still using vlan 1 as their native vlan? In other words, if on the same switch that the ap is connected to, I also have another port that connects to another switch, the default vlan is 1 for that port. How does the switch handle a native vlan 149 on a port that has to traverse vlan 1 to get to another switch? I'm assuming that it would just cross the switches with no problems as long as the vlan is added to the trunk.

Thanks,

John

HTH, John *** Please rate all useful posts ***

Jon Marshall · ‎04-30-2009

John

The native vlan as you know is the vlan that hs no tag attached to frames on a trunk. So it is only locally significant to both ends of a specific trunk ie.

SW1 -> trunk1 -> SW2 -> trunk2 -> SW3

trunk1 and trunk2 do not need to have the same native vlan and there would be no problem if each trunk had a different native vlan. Obviously both ends of the same trunk should agree on the native vlan.

Jon

View solution in original post

Jon Marshall · ‎04-30-2009

John

The native vlan as you know is the vlan that hs no tag attached to frames on a trunk. So it is only locally significant to both ends of a specific trunk ie.

SW1 -> trunk1 -> SW2 -> trunk2 -> SW3

trunk1 and trunk2 do not need to have the same native vlan and there would be no problem if each trunk had a different native vlan. Obviously both ends of the same trunk should agree on the native vlan.

Jon

John Blakley · ‎04-30-2009

Jon,

What I'll end up having is something like this: (native vlan is in ())

AP(149)->switch 1 port(149) -> sw 1 port uplink (1) -> sw2 port uplink(1)

The AP shouldn't have any problems getting to switch 2? (After I write it out like this, it seems that it wouldn't have any problems.) I think things should be okay.

Thanks,

John

HTH, John *** Please rate all useful posts ***

Jon Marshall · ‎04-30-2009

John

AP (149) -> int gi0/1 (149) SW1 int gi0/2 (1) -> int gi0/1 (1) SW2

If that is what you typed out then you will be fine. Sorry but just needed to clarify switch interfaces.

Jon

John Blakley · ‎04-30-2009

Yep, that's it :)

Thanks!

HTH, John *** Please rate all useful posts ***