Spanning tree and 3Com

[ciscolover]

Hi all,

Maybe this is not the correct forum to help me about 3com but I need help because I have problems too when I connect 3com and Cisco.

I have 2 5500g 3com switches conected with 2 links. If LACP is disable, this causes serious problems and STP not works.

Logycally , the link, is a port trunk with all the vlanes permited. One switch has STP enable and the other RSTP.

Why this not works fine? I need to configure MSTP maybe? PVSTP is not allowed on this switches.

Please, could you help me?

[Andras Dosztal]

Which switch is the spanning-tree root? RSTP is backward compatible with STP but only works fine if the root bridge runs RSTP. Otherwise a loop will appear.

With LACP the two links are bundled to a port-channel, and there will be no loops.

BTW, you should use the same protocol for all switches. For a smaller deployments RSTP is fine, in a large environment I recommend MST.

[Kyle McKay]

I too have seem a similar issue related to static LACP configuration on the 3com.

How do you have your LACP configured on both ends?