Configuring STP for a VSS redundancy

franciscotagliaferro · ‎03-18-2015

Greatings;

I need to stablish a VSS redundancy in to two WS-C4507R-E Chassis whit a quad supervisor configuration. So far I haven´t had any problems to verify required configurations to establish redundancy, however when checking if STP config ins needed, in many of the documents says that is not because the VSS redundancy avoids the need for it although in other forums and documents they say that is imperative to configure STP. Do I need it or not?

Best regards.

Jon Marshall · ‎03-18-2015

You should always use STP unless you have a very good reason not to.

With VSS as you say both switches are seen as one logical switch so devices connected to both switches with an etherchannel can forward on all links and STP does not need to block anything.

But the network is usually made up of just more than a VSS pair. And enabling STP protects you against misconfigurations, cabling errors, user errors etc. etc.

It costs very little in terms of bandwidth and personally I would always run it unless like I say there is a technical reason not to.

Jon

Reza Sharifi · ‎03-18-2015

Hi,

I have never been able to produce loop in VSS environment. That said, I would still configure STP just in case.

Its always good to have an extra layer of protection.

HTH

Jon Marshall · ‎03-18-2015

Reza

I have never been able to produce loop in VSS environment

That's because you know what you are doing :-)

I can imagine not running STP and connecting a switch but misconfiguring it where instead of a MEC it was actually two separate etherchannels one to each chassis.

Would that cause a loop or because there is only one control plane does VSS not allow this ?

Jon

Reza Sharifi · ‎03-18-2015

Jon,

That's because you know what you are doing :-)

Thanks Jon!!

I can imagine not running STP and connecting a switch but misconfiguring it where instead of a MEC it was actually two separate etherchannels one to each chassis.

Would that cause a loop or because there is only one control plane does VSS not allow this ?

Have never try this one before, but certainly is a good one to try.

I make a note of it and when we have the next opportunity to try this (sometimes in June or July) will give it a try and let you know. If someone else has a test environment and can test it before I can, that would be good too.

Thanks,

Reza