3Com SuperStack 3C17300 Implementation Manual page 35

IGMP Multicast Filtering 37
Management Interface Reference Guide supplied on your Switch
CD-ROM.
If IGMP multicast learning is not enabled then IP multicast traffic is always
forwarded, that is, it floods the network.
For information about configuring IGMP functionality on an endstation,
refer to the user documentation supplied with your endstation or the
endstation's Network Interface Card (NIC).