9-99
Configuring Advanced Features
Multimedia Traffic Control with IP Multicast (IGMP)
Configuring Advanced
Features
■ Switch 1 ignores IGMP traffic and does not distinguish between IP multi-
cast group members and non-members. Thus, it is sending large amounts
of unwanted multicast traffic out the ports to PCs 2 and 3.
■ Switch 2 is recognizing IGMP traffic and learns that PC 4 is in the IP
multicast group receiving multicast data from the video server (PC X).
Switch 2 then sends the multicast data only to the port for PC 4, thus
avoiding unwanted multicast traffic on the ports for PCs 5 and 6.
Figure 9-67. The Advantage of Using IGMP
The next figure (9-68) shows a network running IP multicasting using IGMP
without a multicast router. In this case, the IGMP-configured switch runs as a
querier.
PCs 2, 5, and 6 are members of the same IP multicast group.
PC X
Video
Server
Router
Router
PC 1
Video
Client
Switch 1
Router
Router
Switch 2
PC 2
PC 3
PC 4
Video
Client
PC 5
PC 6
Multicast
Data Stream
IGMP is NOT
Running Here
IGMP IS
Running Here
