Core01 fails while connecting a L2 Switch

[motiar]

Today I encountered a problem. As you see the attached topology, for some reason I wanted to connect the Test-SW to the production environment. As soon as I connected the Test-SW to SW02, I realized the connectivity problem across the network. After around 25/30 seconds, the connection restublished. After aound 2 hours, as soon as I disconnected the Test-SW from SW02, there was a connectivy problem again and after 30/40 seconds the connectivity restublished. All Switches connected with CORE01 were effected, eventhough some Switches have redundant links with CORE02.
All access Switches are 2960 series with PoE, Test-SW (used Switch) was reseted to factory default before it was configured to VTP mode client. VTP is active in network and CORE01 & CORE02 are VTP mode Serve, Server-SW is VTP mode transparent and all other access switches are VTP mode client. HRSP is active, CORE01 is active and CORE02 is standby.

Do you have any idea, why CORE01 (and all other Switches) was failed during Test-SW's connection & disconnection.

Regards

Motiar

[johnd2310 · Accepted solution]

Hi,

This sounds like a spanning tree issue. What is your spanning tree configuration on the switches?

Thanks

John

[motiar]

Hi John,

Thank you for your feedback.

For your better understanding I attched here the configurations of some Uplinks and accessports. The configuration of some Switches are different from others.

If you need more information, please let me know.

[Georg Pauwen]

Hello,

post the output of 'show spanning-tree vlan x' from the Core01 switch. Judging from your drawing, you want that switch to be the primary root for your VLANs...

[motiar]

Hi,

It was indeed a spanning-tree issue. I got it.

Thank you for your attention.

[motiar]

Hi,

indeed, it was a typical STP behaviour. If you are conneting a new switch to the network, there is path selection process and during this time the network may interrupt. But in my case the interrruption was a bit longer then usual.

Regards

Motiar