Nonblocking Copy Networks for Multicast Packet Switching

Abstract

In addition to handling point-to-point connections, a broadband packet network should be able to provide multipoint communications that are required by a wide range of applications such as teleconferencing, entertainment video, LAN bridging, and distributed data processing. The essential component to enhance the connection capability of a packet network is a multicast packet switch , capable of packet replications and switching, which is usually a serial combination of a copy network and a point-to-point switch. The copy, network replicates input packets from various sources simultaneously, and then copies of broadcast packets are routed to their final destination by the switch. A nonblocking, self-routing copy network with constant latency is proposed in this paper. Packet replications are accomplished by two fundamental processes, an encoding process and a decoding process. The encoding process transforms the set of copy numbers, specified in the headers of incoming packets, into a set of monotone address intervals which form new packet headers. This process is carried out by a running adder network and a set of dummy address encoders. The decoding process performs the packet replication according to the Boolean interval splitting algorithm through the broadcast banyan network. Finally, the destinations of copies are determined by the trunk number translators. At each stage of the broadcast banyan network, the decision making is based on a two-bit header information. This yields minimum complexity in the switch nodes.