Remove no spanning-tree

Unanswered Question
Mar 18th, 2009

I need to allow spanning tree on VLAN 906. How can I remove that VLAN from config below?


spanning-tree mode pvst

spanning-tree extend system-id

no spanning-tree vlan 150,221,401-412,414-453,501-512,514-553,601-612,614-648

no spanning-tree vlan 650-653,701-712,714-753,801-812,814-853,901-912,914-953

no spanning-tree vlan 1001,1006-1012,1014-1035,1037-1053,1101-1109,1111-1112

no spanning-tree vlan 1114-1117,1119-1127,1129,1131,1133,1135,1137-1153,2001

no spanning-tree vlan 2002,2050,3000,3333

I have this problem too.
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Jason Caron Wed, 03/18/2009 - 10:21

I have tried that and when I go look at my config it does not change.

John Blakley Wed, 03/18/2009 - 10:29

Have you tried redoing the line, but instead of 901-912, do 901-905, 907-912?



Jason Caron Wed, 03/18/2009 - 10:37

Yes I have tried that without any success. Could this result from the number of VLANs I have on the switch? Can only so many vlan have spanning tree enabled?

Giuseppe Larosa Wed, 03/18/2009 - 11:03

Hello Jason,

your understanding is correct low end switches can have more vlans defined then number of STP instances

It is likely the commands you see have been automatically inserted by the switch.

if you are not already doing it I suggest to manually configure the list of permitted vlans on all trunk ports including uplinks.

this can free some STP instance

Hope to help


Jason Caron Wed, 03/18/2009 - 11:22

Sadly this Switch is the Core Switch in a hotel with a 1000 rooms. Each VLAN refers to specific room in the hotel. Is there anyway to get STP to run on every VLAN?

Giuseppe Larosa Wed, 03/18/2009 - 11:30

Hello Jason,

depending on the platform an IOS upgrade can help.

It can provide an higher number of concurrent STP instances

Also an IOS image capable of MST can overcome this limitation (MST can associate multiple Vlans to a single STP instance).

what model and IOS image is involved ?

Hope to help


Jason Caron Wed, 03/18/2009 - 11:36

Model number: WS-C3550-24-SMI

System image file is "flash:c3550-ipbasek9-mz.122-25.SEE4.bin"


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