Spanning Tree Inter-connect with Catalyst

[zubairgondal77@gmail.com]

Dear Support Team,

We are facing issue with dual fiber links with our core Switches and distribution level Switches.

Network network hierarchy.

We are having two Core Switches (Models x510-28GSX), two distribution level Switches (Models-ATGS924M).

both cores are stacked & up linked with single fiber patch cord from distribution Switches.

Trouble:

Whenever we are trying dual up links from L2 Switches network is stop sending traffic, kindly assist us for configuration L3 & L2 Switches how we can keep redundancy with out loop.

For more understanding kindly find attachments.

[balaji.bandi]

You having spanning tree loop in the network and you need to understand spanning tree how it works and how to mitigate,

Below some cheat for you to understand, more information can be found in cisco site.

http://packetlife.net/media/library/11/Spanning_Tree.pdf

[paul driver]

Hello

Are all interconnects between these switches trunked?

Are all switchs running stp, if so what mode?

Do you have any kind of stp bpdu filtering or trunk portsfast applied on the interconnects?
Is the Core stack is the stp root if it isnt make it so?
Are you receiving any logging, is so what is it saying?