I need a clear answer to why do I need a NATIVE VLAN if I disable VLAN 1.

[Alexvue]

One of my co-worker disable the NATIVE VLAN 1 but he did not create a NATIVE. I need a clear answer as to why I do need a NATIVE or why do I not need a NATIVE VLAN? I have about seven VLAN on my Cisco switches network and I've trunk ports between switches and lots of servers. Please HELP clarify I need a NATIVE VLAN OR NOT?

[Jon Marshall]

On Catalyst switches you cannot disable vlan 1, you can shut the L3 interface down and you can remove it from a trunk but the switches will still use that vlan. 

If you do not specify another native vlan then it is by default vlan 1 and because you cannot disable that vlan you have a native vlan whether you want one or not. 

So most people simply choose a vlan that has no end ports in it and no L3 SVI for it and make that the native vlan. 

Or if the switches support it you can tag the native vlan as well. 

Jon

[Alexvue]

Jon,

I've 9372 switches as my core switches/router, 3850 switches and 3650 switches. Vlan 1 is disable and I've lots of output error. I've an old access database that corrupt every day but my co-worker keeps saying that we don't have a need for NATIVE VLAN. is there a way to prove that we need NATIVE VLAN?

[Jon Marshall · Accepted solution]

The native vlan is there so you can connect to switches that don't understand tagging but virtually all switches do now. 

So it's not that you need a native vlan it's that with Catalyst switches you can't get rid of it for the reasons I stated earlier but you can change which vlan is used for the native vlan. 

Unless, as also mentioned,  you specifically tag the native which is an option on some switches. 

Nexus switches may have different rules on this but I have limited experience with them. 

I would simply choose another vlan as native and use it on all your trunk links to see if that rectifies the problem, although it may have nothing to do with the native vlan, hard to tell from your description. 

Jon