6

SWITCHING PRINCIPLES FOR MULTICAST, MULTIRATE, AND MULTIMEDIA SERVICES

A challenge of modern broadband digital networks is to efficiently support multirate and multicast connections for providing high-speed multimedia services. These services often have diverse quality-of-service (QoS) requirements. A key to the success of the future broadband network deployments, therefore, lies in the design of a high-speed packet switch to cope with these three m's. In this chapter, we first present several fundamental switch design principles for multicasting. Then, we introduce the concept of path switching, which combines the advantageous elements of both dynamic and static routing. A cross-path switch is a Clos network operated under the principle of path switching. We shall show how cross-path switches can integrate various switch design principles together to support multirate, multicast, and multimedia traffic efficiently.

6.1 MULTICAST SWITCHING

So far we have been focusing on point-to-point switching in which an input packet is targeted for one and only one output. Many communication services, such as telephone calls, are point-to-point in nature and involve only two parties. At the other end of the spectrum, we have services such as television broadcast in which the same programs are received by all network users. The most general form of network connectivity is point-to-multipoint, in which information from one source is sent to a selected group of destinations. A three-party video ...

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