Looks like TCP5.0 supports V2 of IGMP standard (RFC2366). Customer 
switch supports V3 (RFC 3376).
Think I will have to do hack to send V3 out myself in addition to V2. 
Anyone had same issue.
Also found strange behavior with TCP 5.0 multicast.
Have 3 multicast streams coming into program (239.192.69.45/5080, 
239.193.69.45/5080,239.194.69.45/5060).
Strange behavior in that TCP stack seems to ignore multicast address for 
the first 2 streams and just accepts any multcast address as long as 
port is good. So I am getting
data on second socket, even if only first multicast is active. Same 
behavior if second multicast is active, last multicast works 
fine....still investigating and keeping fingers crossed that it is my bad !!

Dave Allamby