Question about STP and multiple VLANs

[shikamarunara]

I've configured my core switch to be the primary root for 3 vlans. On 2 vlans, everything seems to be showing up fine, on a third vlan I have "Spanning tree instance(s) for vlan X does not exist." Does someone know what this could be from?

-Shikamaru

[etamminga · Accepted solution]

Do you have any ports up in that VLAN?

Regards,

Erik Tamminga

[bjw · Accepted solution]

Yup,

You have to have at least 1 active interface/port in a VLAN for it to come up

[shikamarunara]

Misconfigured trunk port. Looks good now. Thanks.

-Shikamaru

[sundar.palaniappan]

Shikamaru,

In addition to what the previous posters stated I would add if you have a trunk in which a VLAN is active that would cause the STP instance for that VLAN to be enabled as well. Since you already had active trunks, I assume your trunk must have been filtering/blocking the VLAN in question and that probably was the cause of the problem.

HTH

Sundar