Native VLAN

Answered Question
Apr 29th, 2009

When using Native vlan 99 on both switches, should I prune or allow this vlan on the do1q trunk link?

The Native vlan carried untagged traffic over the trunk link?

Thanks

SW1

int G0/1

switchport

switchport mode trunk

switchport trunk encapsulation dot1q

switchport trunk native vlan 99

switchport trunk allow vlan 10,20,99

SW2

int G0/1

switchport

switchport mode trunk

switchport trunk encapsulation dot1q

switchport trunk native vlan 99

switchport trunk allow vlan 10,20,99

Correct Answer by Edison Ortiz about 7 years 10 months ago

Best Practice is NOT to use Vlan1 at all. It should be left for control packets.

All packets are untagged on the native Vlan.

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Edison Ortiz Wed, 04/29/2009 - 12:30

If you manually prune this Vlan, it will stop sending traffic over it and break the native vlan connectivity.

Yes, the native vlan carries untagged traffic but it is still part of the trunk.

The command 'show int trunk' will display the Vlans that are in forwarding state and not pruned.

__

Edison.

colmgrier Wed, 04/29/2009 - 12:42

Thanks for the reply.

Is it Cisco best pratice to use any vlan rather than vlan 1 for the Native vlan?

What packets are untagged on a switch that use this native vlan?

Correct Answer
Edison Ortiz Wed, 04/29/2009 - 12:53

Best Practice is NOT to use Vlan1 at all. It should be left for control packets.

All packets are untagged on the native Vlan.

Jon Marshall Wed, 04/29/2009 - 13:37

"Is it Cisco best pratice to use any vlan rather than vlan 1 for the Native vlan?"

Yes and in addition it also best practice to choose a vlan for your native vlan that

1) does not have any ports allocated into it for user machines/servers etc.

2) does not have a L3 vlan interface. There is no need to route the native vlan.

Jon

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