Native VLAN

Answered Question
Apr 29th, 2009
User Badges:

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 8 years 2 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.



  • 1
  • 2
  • 3
  • 4
  • 5
Overall Rating: 5 (1 ratings)
Loading.
Edison Ortiz Wed, 04/29/2009 - 12:30
User Badges:
  • Super Bronze, 10000 points or more
  • Hall of Fame,

    Founding Member

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
User Badges:

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
User Badges:
  • Super Bronze, 10000 points or more
  • Hall of Fame,

    Founding Member

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
User Badges:
  • Super Blue, 32500 points or more
  • Hall of Fame,

    Founding Member

  • Cisco Designated VIP,

    2017 LAN, WAN

"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

Actions

This Discussion