spanning tree

Unanswered Question
Jun 17th, 2008

Hi all, if I have spanning tree turned off on all my uplinks, am i right in saying, no switch will send spanning tree bpdu's to the neighbour switch? and so also each switch will assume its the root?

I have this problem too.
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michaelchoo Wed, 06/18/2008 - 17:45

Wrong. Turning off spanning tree will NOT stop BPDU from being sent out. What it will do is the switch will NOT check for Layer-2 loop. So, let's say you link up 2 switches with a trunk link, and you turn off spanning tree on the inter-switch port. What you will get is a spanning tree loop.

What's your objective here?

carl_townshend Thu, 06/19/2008 - 03:56

so, if i have a switch with spanning tree turned off just on the uplink to the core switch, will the access switch assume it is the root bridge or not ?

glen.grant Thu, 06/19/2008 - 04:19

There really shouldn't be a reason you need to shut it off if everything is designed correctly.

michaelchoo Thu, 06/19/2008 - 16:45

Question remains... What exactly do you want to do that require spanning tree being turned off? If your uplink to core switch is a trunk, DO NOT turn off spanning tree. If it's access switch, and it's the only link out of the access switch, then you can potentially turn off spanning tree (although I strongly advise against it!)

ashok_boin Thu, 06/19/2008 - 21:32

It's strongly not advisable to turn off STP as told by others but to answer your question....

Root bridge selection concept is the feature of STP. If you are turning off STP, then the concept of root bridge is not there for this particular switch. Hope it clarifies.

-Ashok.

-Ashok.

ashok_boin Sun, 06/22/2008 - 05:41

Reiterating same info, there is no concept of root bridge if you turn off STP.

Assume, you have 10 switches in your network & turned off STP on all switches, then you can remove root bridge concept al together as it's feature of STP.

Regards...

-Ashok.

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