ProLiant BL p-Class Interconnect Switch becoming STP Root Bridge

[Erik Stickel]

Is there a way to configure/prevent the Interconnect switch from becoming STP RootBridge in a Cisco Environment running 802.1Q.

We have Trunking enable to the ICS (three Vlans) and one of the three VLAN's has become root bridge.

In the Cisco Environment we have configured the primary RootBridge and the Secondary bridge , However the ICS has still become the Root bridge. It seems as if the ICS is not learning STP/BPDU's from the Cisco Environment ?

[Jonas Back_2]

I had almost the same problem some time ago and that was because we use Multiple Spanning Tree and use mst 1 and mst 2 in our Cisconetwork.

When we conncted the Internet connecting switch for our BL p- and e-class they became root bridge for mst 0 for some reason. My guess is that the switches doesn't support MST and therefore use mst0 as "default".

And since we hadn't specificed any priorities for mst 0 in our Cisco environment the whole network went down for a few seconds while negotiating for root bridge.

What we did was to specify mst 0 in our Ciscos and gave it a lover priority:
spanning-tree mst 0,2 priority 24576
spanning-tree mst 1 priority 28672

And we gave the Interconnect switches a priority of 32768.

Let me know if this is confusing. It was over a year ago I did this but I think I have some documents explaining how we did it.