Telematics Chapter 6: Network Layer - Freie Universität Berlin

Internet Group Management Protocol (IGMP)
Group
members
● For delivery of multicast messages to all group members that are located in
different physical networks, routers need information about group associations.
● If groups are only temporary, routers have to acquire information about
associated hosts by themselves.
● By means of IGMP messages (encapsulated into IP packets), a router informs all
hosts in its subnet to which groups they belong
● Routers notice the existence of group members
Multicast router
● Periodically, the routers ask (Polling), which groups of multicast are still present
● Routers exchange information to build multicast routing trees
Univ.-Prof. Dr.-Ing. Jochen H. Schiller ▪ cst.mi.fu-berlin.de ▪ Telematics ▪ Chapter 6: Network Layer
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