Hello Tirtha,

you need to implement at least QoS.

Verify also the configuration of the videoconferencing server because they can default to high bit rate codec.

So setting a default codec that uses less bandwidth is important.

Also you should look for some control mechanisms like CAC = Call admission control so that no more then X distinct multicast sessions can be setup.

configuration of IGMP snooping on switches can be a benefit but it is important to verify that the implementation is efficient and doesn't load too much the switch cpu (some investigation on C2950 capabilities is needed).

Using separate Vlans can help but you should be able to implement modular QoS checking the L4 information in packets.

You should provide a LLQ class for VoIP, a class for video, a class for VoIP signalling, a class for data (at least one). CBWFQ can be the right tool to manage BW resources on 2 Mbps links.

Hope to help

Giuseppe