I have a customer, who is facing a strange problem. His current scenario has a couple of Cisco 4500-X core switches (running in VSS) that are connected to some SG-200, old 3com (manageable) and unmanageable access switches. He is running PVST with only vlan-1 configured in his network and his Core-switch ports towards access switches are configured in trunk mode. So, all the production traffic is spanning on vlan1. The problem is that whenever one access switch goes down (e.g. because of power-cuts) the link between core and access switch doesn't come back up. He has to either physically change the port on core switch or restart the core switch to bring up the connection. Every access switch has only one uplink towards the Core, so their is no need of STP actually but in any case I'm curious to know the cause.
What is the are interconnects between the access switches and core ( access or trunk) as you only have one vlan they don't need to be trunks.
Do you have any Port-security, bpduguard applied on the ports, ? What dos the interface status log when the switch goes come back up from the power outage?
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