Hi,
Here are some articles that will help.
http://www.symantec.com/business/support/index?page=content&id=TECH107658
http://www.symantec.com/business/support/index?page=content&id=TECH106929
Your switches and router must be configured to support IGMP.
For more detailed information, see below.
4.2. General information
When configuring your routers, we find that generally the default settings for Group Membership Time, Max Response Time and Query Interval work well. It's probably a trade-off between the volume of IGMP traffic and the volume of Multicast traffic that is sent but with no one any longer interested in listening to it. Since the Ghost Multicast Server ceases sending Multicast packets at the same time that the clients stop listening, the times for Ghost could be made longer to reduce the IGMP traffic volume, but this volume tends to be negligible, so the defaults are probably just as good.
224.0.0.1 is the address of the All-Systems Multicast Group. IGMP-enabled routers send query commands to this address requesting information about all hosts that need to receive Multicast packets. Each host replies with any Multicast addresses it needs to receive.
224.0.0.2, the All-Routers Multicast Group. Hosts send packets to this address when they are no longer interested in receiving Multicast traffic on a certain address.
4.3. RFC2236 - IGMP Version 2
http://www.faqs.org/rfcs/rfc2236.html
4.4. Cisco Group Management Protocol
This is an excerpt from Cisco documentation on their Catalyst Switches.
For more info see:
http://www.cisco.com/univercd/cc/td/doc/product/lan/cat5000/c5k3_1/c5kcg3_1/10multi.htm
CGMP (Cisco Group Management Protocol) works with Internet Group Management Protocol (IGMP) messages to dynamically configure Catalyst 5000 series switch ports so that IP Multicast traffic is forwarded only to those ports associated with IP Multicast hosts.
Doug Snyder, CISSP