Why can't I unassign this port from VLAN1?

Answered Question
May 19th, 2009

On my 3560G, I do 'no switchport access vlan 1'. Then I configure the trunk ports as shown below.

I can't understand why the g0/24 port still appears as part of Vlan1 though. My intention is to remove all ports from Vlan1.

Current configuration : 192 bytes

!

interface GigabitEthernet0/24

switchport trunk encapsulation dot1q

switchport trunk allowed vlan 99

switchport mode trunk

speed 100

duplex full

end

myswitch#show vlan

VLAN Name Status Ports

---- -------------------------------- --------- -------------------------------

1 default active Gi0/24, Gi0/25, Gi0/26

2 VLAN0002 active Gi0/1, Gi0/2, Gi0/3, Gi0/4

Gi0/5, Gi0/6, Gi0/7, Gi0/8

Gi0/9, Gi0/10, Gi0/11, Gi0/12

Gi0/13, Gi0/14, Gi0/15, Gi0/16

Gi0/17, Gi0/18, Gi0/19, Gi0/20

Gi0/21, Gi0/22, Gi0/23, Gi0/28

999 VLAN99 active

I have this problem too.
0 votes
Correct Answer by andrew.butterworth about 7 years 6 months ago

This is because the port is a trunk and by default the command 'switchport trunk native vlan 1' is configured (but not visible as its a default). If you want to change the Native VLAN on a trunk port issue the interface command:

'switchport trunk native vlan x'

where 'x' is the native VLAN you want to use.

The native VLAN must match on either end of the link or you could have STP issues and probably lots of Native VLAN mismatch errors.

HTH

Andy

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Correct Answer
andrew.butterworth Tue, 05/19/2009 - 13:56

This is because the port is a trunk and by default the command 'switchport trunk native vlan 1' is configured (but not visible as its a default). If you want to change the Native VLAN on a trunk port issue the interface command:

'switchport trunk native vlan x'

where 'x' is the native VLAN you want to use.

The native VLAN must match on either end of the link or you could have STP issues and probably lots of Native VLAN mismatch errors.

HTH

Andy

glen.grant Tue, 05/19/2009 - 16:54

I'm surprised it even shows up if the trunk is active . Seems whenever I have done a show vlan on a trunk port it does not show what vlan it is in . In order to get it to change I believe he may have to use "switchport access vlan 9 " . Are those trunk ports actually working ?

davy.timmermans Wed, 05/20/2009 - 10:24

I agree with Glen. I think that the trunk port is not up.

Andrew,

The fact the port shows as vlan 1 has nothing to deal with the "native" vlan but with the fact that the default access vlan is 1.

If you have

int gig0/1

switchport mode trunk

switchport access vlan 25

switchport native vlan 5

switchport trunk allowed vlan 9

if the trunk is not up, the port will be reported as an access port in vlan 25 and not 9

John Blakley Wed, 05/20/2009 - 10:36

My question is:

999 VLAN99 active

This is show vlan 999.....do you have your switchport in the right vlan? You show in the config that it's set to 99.

I agree with everyone else on the trunk. If it shows in the vlan command, then it's not configured as a trunk port. They disappear from the "sh vlan" when the port is configured as a trunk.

You can also do "sh int g0/24 trunk" and see if it shows that it's actually trunking.

HTH,

John

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