User's Manual

Advanced Configuration
Figure 5-79 IGMP Snooping Process
The router forwards the IP multicast data to the BSU/End Point A.
Lets say, with IGMP Snooping not enabled on the BSU/End Point A, the multicast data is transmitted over the wireless medium
irrespective of whether the multicast group address is a member of the multicast group table maintained in each BSU/End Point
A. With IGMP Snooping enabled, the BSU/End Point A transmits the data only when the multicast group address is a member of
the multicast group table, else drops the packet. The SU/End Point B will receive the multicast data.
Similarly, with IGMP Snooping not enabled on the SU/End Point B, the multicast data is transmitted irrespective of whether the
multicast group address is a member of the multicast group table maintained in each SU/End Point B. With IGMP Snooping
enabled, the SU/End Point B transmits the data to the host only when the multicast group address is a member of the multicast
group table, else drops the packet.
IGMP Snooping is of 2 kinds:
• Active: Active IGMP Snooping listens to IGMP traffic and filters IGMP packets to reduce load on the multicast router.
• Passive: Passive IGMP Snooping simply listens to IGMP traffic and does not filter or interfere with IGMP.
Tsunami® 8100 Series - Software Management Guide 129