Abstract
Multicast is a transmission service that simultaneously delivers packets from a sender to a group of receivers. The set of receivers form a multicast group logically identi?ed by a unique multicast address. In a network with network level multicast support (e.g. IP) a copy of each packet is transmitted once on each link of a directed tree rooted at the sender with the receivers as leaves. In the public Internet, IP Multicast in an extension to the basic routing and forwarding model, endowed with its own address space, signaling (IGMP), and routing protocols (MOSPF, DVMRP, PIM).
Key Terms in this Chapter
Leader: In a single-rate protocol, it is the receiver responsible for sending regular feedback to the sender.
Join Experiment: Attempt done by a receiver in a multiplerate protocol to increase the reception rate by joining an additional layer.
Multiple-Rate Protocol: A congestion control protocol that can provide diverse transmission rates to different receivers.
Single-Rate Protocol: A congestion control protocol that delivers the same flow of data to all receivers simultaneously.
TCP-Compatible: Protocol said of a congestion control protocol that obtains the same throughput that a conforming TCP implementation would obtain under identical circumstances.
Layered Multicast: A multicast transmission in which information is divided in segments carried over different multicast groups.
Feedback Implosion: In a multicast protocol, when a large group of receivers sends information nearly simultaneously to the sender, possibly overwhelming the capacity of the network links near the sender.