Multicasting and spanning tree issues

[samba_man]

I'm having a problem building computers that are on anything other than the core switch (3Com Baseline 2928-SFP Plus) on our RM CC4 network. If I try to build a machine that is on a different switch, most of the time an IP address isn't picked up and the build fails. I gather the cause is likely to be multicasting and spanning tree not getting on very well.

 

We've got a star network with two cables going from the core switch to each of the four other switches (all are 3Com Baseline 2924-SFP Plus). I'm worried that if I turn off spanning tree to see if it's causing the problem, a loop will form.

 

My questions are:

 

Would the dual network cables be for redundancy or increased bandwidth?

 

Is there a way to have the best of both worlds and have loop protection and allow multicasting to work?

[kevin_lane]

You could put them on a different vlan if you use vlans

[ChrisH]

If your ports are set up as a trunk or link aggregation there will not be loop. If they aren't in a trunk and spanning tree is blocking one then obviously you will get a loop.

[m25man]

I take it you have set igmp snooping correctly?

The switch cannot build an L2 forwarding table for multicast traffic unless you do!