How should I configure Spanning Tree

Question

Hi,

I have several core Dell switches using PowerConnect 6224s mostly - these ink into my provider's Cisco kit. We run several VLANs and have redundant links between stacked switches.

I've read up on spanning tree and have the following tasks:

1. Map out the network - including ID root bridge, root ports, blocked paths, max age and helo time

Once I've done my analysis information, I'm not sure how to best optimize the spanning tree config, so far I have:

1. Ensure RSTP is enabled on all switches
2. Ensure all edge ports have spanning tree port fast configured
3. Do not declare spanning tree port fast on links between switches
4. Force speed and duplex settings on all link ports between switches (I assume this is because auto negotiate takes longer?)

What I'm not sure about is:
1. Should I enable BPDU guard and if so, where?
2. Should I enable root guard and if so, where?

I've read Todd's informative article: http://en.community.dell.com/support-forums/network-switches/f/866/t/19465205.aspx

But, I'm not sure where\whether I should be configuring the guard options - am happy to provide additional info as needed.

Thanks

aetius80 · Answer

Thanks for the reply,

I've read throught your links and have a few questions. Am I right in thinking that the root bridge should be at the centre of the network as it is used in calculating the least cost path across the network?

Also, I'm thinking of using auto edge instead of bpdu guard as the bpdu guard requires manual intervention.

We had a network issue in the past, where I suspect our ISP changed spanning tree costs and caused one of our switches to go down - I've seen the option to enable root and loop guard, but the problem is that if I did enable this on our main uplink to our ISP, with this setting enabled, all that would happen (if I'm correct) is that our main uplink would fail.

Any tips would be appreciated - thanks in advance...

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How should I configure Spanning Tree

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