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Community Member

Flat Network & no Spanning tree?

I have a large network with 8 2950 powered by 2821, with 30 vlans. The network has no loops or redundancy. Question 1 do I need to have spanning tree running and why?

If not how do I disable it?


Re: Flat Network & no Spanning tree?

I am sure you have heard the line "run the spanning-tree even when you do not have any loops in the network" and generally our recommendation is to leave it on which is default even if you have no redundancy but have etherchannels ( etherchannels with ON mode can cause transient spanning-tree loops ) .

Traditionally the problem that people have had with spanning-tree has large convergence times ( of the order of 30 - 50 seconds ) and some one coming from SONET , optcal background ( the folks who are used to the convergence times of 50 msec ) dont genrally like that. So the bottom line is you can turn it off so long as you make sure you have absolutely no redundancy and no etherchannels.

the command is as simple as

no spanning-tree

on all IOS based switches.

Hope this helps.


Salman Z.

Community Member

Re: Flat Network & no Spanning tree?

There are no etherchannels either. The deployment is in wisp environment. The “links” between the switches are high end point to point 45mbs wireless radios. The locations of the sites are such that ring topology is not possible. Furthermore the budget prevents duel radios to sites.

Community Member

Re: Flat Network & no Spanning tree?

you can disable the spanning tree in your network environment if there is no loop. But please make a careful consideration that you will not add other switches to your production network, this may bring underlying risk which can destroy your network in one or two seconds.

Re: Flat Network & no Spanning tree?

Hi Friend,

If you are sure you have no loop in network and you are sure no one else can connect other switches and can make a loop in your network you can very well go ahead and disable spanning tree.

Enabling STP will definetely bring some overheads in your network like BPDU travel across the network every 2 sec. You can stop some extra overheads in your network.

Another advantage will be faster convergence as compared to STP which takes approx 50 sec depening upon your topology.



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