Combine VLANs

[Kmeijer_BF]

Hi there,

We currently have a WS-C3850-12XS stack on 16.3.3 with 2 nodes.

This stack has a port channel, assigned to VLAN1 on which we are connected to the outside world, however I want to move this to a different VLAN since VLAN1 is not supported on all of our equipment.

Would it be possible to merge or combine 2 different VLANs for this migration? Or in any other way make it so that another VLAN would also end up on the same port channel as if it was on VLAN1 without routing?

[marce1000]

 - You can't merge VLAN's , but you can configure the port-channel as a trunk ,allowing more then one VLAN.

 M.

[Kmeijer_BF]

Could you explain why that would help me? Because the WAN connection has no VLANs, its all untagged.

[marce1000]

  - Then configure the VLAN intended to carry-on the WAN connection as the native VLAN with :

                  switchport trunk native vlan x

 M.

[Deepak Kumar]

You can't combine two VLAN's but make Port-Channel as trunk as:

interface port-channel 10 <---- your port-channel number/ID

switchport mode trunk

switchport trunk allowed vlan add X,y <-- only required VLAN ID's

Switchport trunk native vlan x <----- VLAN which is for ISP

no shut

!

[Richard Burts]

We do not know much about this situation and that makes it difficult to give good advice. We know there is a 3850 stack, we know there is an EtherChannel and we know that there is vlan 1, and we know that vlan 1 provides connectivity to outside. We do not know if there are any other switches, we do not know if there are any other vlans, we do not know if routing is enabled. And I am trying to understand why vlan 1 is a problem for some equipment. If the original poster can provide additional information it would help us give better advice.

Based on the very little that we know I do have one suggestion about merging another vlan into vlan 1. If there is another switch in the network then configure ports in that switch to be in vlan 2. Assign the equipment that has issues with vlan 1 to ports in the other switch on vlan 2. Connect an access port in vlan 2 of that switch to an access port in vlan 1 on the 3850. This will effectively merge vlan 2 of the second switch with vlan 1 of the 3850. This works because when going over an access port there is no vlan tagging and the receiving switch has no knowledge of the vlan membership of the sending switch.

If there is not another switch then I do not know of a way to merge a second vlan into vlan 1.

[Joseph W. Doherty]

Could you further clarify what's meant by ". . . VLAN1 is not supported on all of our equipment."

To your second question, yes it's often possible to "merge" VLANs (at L2), but the converse is a different issue.