User`s manual

PT-G7509 User’s Manual Featured Functions
3-59
Multicast Filtering
Multicast filtering ensures that only end-stations that have joined certain groups receive multicast
traffic. With multicast filtering, network devices only forward multicast traffic to the ports that are
connected to registered end-stations. The following two figures illustrate how a network behaves
without multicast filtering, and with multicast filtering.
Network without multicast filtering
STAT
FAULT
PWR1
MASTER
PWR2
COUPLER
LNK/ACT SPEED FDX/HDX
RING PORT
COMUPLER 
PORT
MODE
1 2 3 4 5 6 7 8 9
All hosts receive the multicast traffic, even if they don’t need it.
Network with multicast filtering
IGMP Group2
Group 1 Multicast Stream Group 2 Multicast Stream
IGMP Group1 IGMP Group2 IGMP Group1
STAT
FAULT
PWR1
MASTER
PWR2
COUPLER
LNK/ACT SPEED FDX/HDX
RING PORT
COMUPLER 
PORT
MODE
1 2 3 4 5 6 7 8 9
Hosts only receive dedicated traffic from other hosts belonging to the same group.