Native VLAN on Cisco Switches

[asadrizvi1]

I have a question regarding the default native  vlan, I have a cisco based environment and I set vlan XXX on a native on  trunk links, I also running Multiple Spanning Tree on my switches &  create instances for vlan segregation.

My question is here could I put vlan 1 (default) in any of instance or not?

Thanks & Regards,

[daniel.dib]

With MST, it is not running per VLAN spanning tree, it sends all BPDUs via instance 0 which is called the CIST. These frames are sent untagged via the native VLAN. Normally this is VLAN 1 but if you change it to another VLAN then the BPDUs are sent untagged on that native VLAN.

Regarding if to use instance 0 or not, it is often recommended to create as many instances as you need to create the desired topology (usually two) and put your VLANs in those instances. It's a good pratice to map all your VLANs straight away because changing the instance to VLAN mapping makes the MST region become multi region until they all have the same instance to VLAN mapping.

I would keep all VLANs out of instance 0 but it's definitely possible to have VLANs mapped in instance 0 as well.

Daniel Dib
CCIE #37149

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