Technical data

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CHAPTER 13
IGMP
Internet Group Management Protocol (IGMP) is used by IP Multicast routers to learn about the
existence of host group members on their directly attached subnet (see RFC 2236). The IP Multicast
routers get this information by broadcasting IGMP Membership Queries and listening for IP hosts
reporting their host group memberships. This process is used to set up a client/server relationship
between an IP Multicast source that provides the data streams and the clients that want to receive
the data.
The G8000 can perform IGMP Snooping, and connect to static multicast routers (Mrouters).
The following topics are discussed in this chapter:
 “IGMP Snooping” on page 181
 “IGMPv3 Snooping” on page 183
 “Static Multicast Router” on page 185
 “IGMP Relay” on page 186
 “IGMP Filtering” on page 188
IGMP Snooping
IGMP Snooping allows the switch to forward multicast traffic only to those ports that request it.
IGMP Snooping prevents multicast traffic from being flooded to all ports. The switch learns which
server hosts are interested in receiving multicast traffic, and forwards it only to ports connected to
those servers.
IGMP Snooping conserves bandwidth. With IGMP Snooping, the switch learns which ports are
interested in receiving multicast data, and forwards multicast data only to those ports. In this way,
other ports are not burdened with unwanted multicast traffic.