MNS-BB
Software User Guide
-63-
Figure: The Advantage of Using IGMP
The next figure (below) 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. IGMP is configured on switches 3 and 4.
Either of these switches can operate as querier because a multicast router is not present on the
network. (If an IGMP switch does not detect a querier, it automatically assumes this role, assuming
the querier feature is enabled—the default—within IGMP.)
Figure: Isolating IP Multicast Traffic in a Network
In the above figure, the multicast group traffic does not go to switch 1 and beyond because either
the port on switch 3 that connects to switch 1 has been configured as blocked or there are no
