Single Switch, Multiple Trunks - Different Native VLAN's?

[Ian Moore]

Hi, I am using a 3750 switch and have a question regarding the native VLAN.  Are there any issues with creating multiple trunk ports on a switch that are assigned different native VLAN's?

I know the native VLAN of both sides of the trunk link  must match, but does the native VLAN need to match on all trunk ports on a switch or can any VLAN defined on a switch be assigned as the native VLAN on a trunk port?

Thanks

[Hari Vishnu · Accepted solution]

Hi,

Technically I could not see any issue. But can be please brief the business reason that prompted you for this ?

Thanks,

H

[Ian Moore]

Thanks Hari,

I have a inter site link connecting two sites.  The link is to be upgraded to a dot1q link so I need to change the connecting ports (switch ports currently in access mode) to trunk ports to pass tagged packets over the link.

The native vlans for the exiting trunk links on the switch are different on either side of the link.  Side A trunk ports have a native VLAN of 100.  Side B trunk ports have a native VLAN of 101.  The exiting trunks are used to connect to routers / switches etc at the local site and are not connected to the inter site link. 

I have two VLANs that span both sites (130 & 140) so my plan was to use VLAN 130 as the native VLAN for the trunk the ports connected to the inter site link.  Connectivity for only one of the VLAN's (130) works at the moment, hence the link upgrade to a dot1q tunnel to enable passing of VLAN 140 traffic between sites.

This creates a scenario whereby I have multiple trunks on the same switch that have different native VLAN's.  Just wanted to check this doesn't go against best practice.

[John Blakley · Accepted solution]

You won't have any issues with this...

HTH,

John