Trunk only two vlans, cannot remove others

wilson_1234_2 · ‎07-30-2007

I have a 3550 switch that I am trying to set up a trunk port and only trunk two VLANs.

When I try to remove all VLANs other than what I want, I get this message:

"Command rejected: Bad VLAN allowed list.

VLANs 1,1002-1005 are required."

Do I have to allow these VLANs?

lamav · ‎07-30-2007

Yes. You can never disallow vlans 1002 through 1005. Those are native to the IOS.

All you have to do is type "switchport trunk allowed vlan x,y,z"

The rest will be pruned by default.

wilson_1234_2 · ‎07-30-2007

thanks everyone

sundar.palaniappan · ‎07-30-2007

Wilson,

Those are default VLANs that you couldn't remove in the past. But the newer IOS lets you remove the default VLANs from the trunk. Here's a small capture from my lab switch.

SW1-3550#show run int f0/24

Building configuration...

Current configuration : 154 bytes

!

interface FastEthernet0/24

switchport trunk encapsulation dot1q

switchport trunk allowed vlan 100

switchport mode trunk

switchport nonegotiate

end

SW1-3550#show int trunk

Port Mode Encapsulation Status Native vlan

Fa0/24 on 802.1q trunking 1

Port Vlans allowed on trunk

Fa0/24 100

Port Vlans allowed and active in management domain

Fa0/24 100

Port Vlans in spanning tree forwarding state and not pruned

Fa0/24 100

HTH

Sundar

lamav · ‎07-30-2007

Sundar, you can prune those vlans by default by not including them in the 'allowed vlan' statement. Correct?

sundar.palaniappan · ‎07-30-2007

Correct.