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Spanning Tree

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BOVC
Advisor

Spanning Tree

Hi,

I'd like to setup spanning-tree on our new 5406zl switches. However, it's like the only stp implementation supported on these switches is MSTP (Multiple-instance STP) - can this really be true?

Anyway, even if this is the only way I guess thats how its gonna be. Only problem is that MSTP is a whole lot more complicated that RSTP and STP. So I was wondering if anyone has a document or link or whatever to something that describes MSTP in an easy way? I've read the HP manual, but it's pretty confusing.

Thanks in advance,
Rasmus
5 REPLIES
Matt Hobbs
Honored Contributor

Re: Spanning Tree

Hello Rasmus,

It is true, however MSTP is designed to be backwards compatible with the 802.1D and 802.1w standards.

If you want to keep it very simple and just use spanning-tree like the usual single instance spanning-tree versions, all you need to do is enable spanning-tree on the switch:

5406(config)# spanning-tree

The other thing to look out for is that by default, ports are set to the edge status of no (802.1w defaulted to yes on the 5300's). So for your end nodes it is recommended that you set the edge port status:

5406(config)# spanning-tree edge-port

Hope this helps.
BOVC
Advisor

Re: Spanning Tree

Sounds great - thanks. But what about IST, MST and MSTI instances etc.? It's not necessary to have these things in place?

Rgds,
Rasmus
Matt Hobbs
Honored Contributor

Re: Spanning Tree

If you're not going the full MSTP route, then yes you can just ignore them and leave everything at the defaults.
BOVC
Advisor

Re: Spanning Tree

Hi,

Basically this is my setup (attached). Each link is actually a 2 fiber trunk. We use 8 VLANs which has been configured on all switches. The main switch does the routing between them.

Now, does this setup allow what you describe?

Is the default settings just some kind of 1 region, 1 IST, 1 MSTI thing?

And 1 last thing :)
The edge port setting - is that used to define whether or not the attached device is a STP-supported device, or for defining whether multiple IP-addresses will come through this interface (if e.g. a router, switch or a firewall is connected to the port)?

Thank you very much for your assistance,
Rasmus
Matt Hobbs
Honored Contributor
Solution

Re: Spanning Tree

With that network map, if you are setting those 2 port trunks up as trunks, then there really is no need to even use spanning-tree at all (I'd still recommend it though as users have a knack of creating accidental loops).

With just spanning-tree enabled, the common spanning tree (CST) is the active tree. If you have multiple switches that run MSTP, but you don't configure any MSTP regions - then every MSTP switch will consider itself the root of the Internal Spanning Tree (IST). There is no need to worry about this, just ignore it.

When you do a 'show span' all you need to look at is the CST.

For the edge-port setting, you should set PC's / Servers to edge-port... it is only switch to switch links that you should leave as no edge-port.

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