Switch modules, the building blocks of this system, are independently operated packet switches. Each module consists of a Batcher sorting network, a stack of binary trees, and a bundle of banyan networks. The modular architecture is a unification of the Batcher-banyan switch and the knockout switch, and can be physically realized as an array of three-dimensional parallel processors. Switch modules are interconnected only at the outputs by multiplexers. The partitioned switch fabric provides a flexible distributed architecture, which is the key to simplify the operation and maintenance of the whole switching system. The modularity implies less stringent synchronization requirements and makes higher-speed implementation possible. The proposed modular switch is intended to meet the needs of broadband telephone offices of all sizes. It is estimated that a modular switch with terabit capacity can be built using current VLSI technologies. >

A modular architecture for very large packet switches

The author shows how the bandwidth available through the use of multiwavelength optical-fiber technology can be used to achieve novel large-capacity switching systems to address anticipated switching bottlenecks. He does so by describing the features and network applications of a specific multiwavelength network, the Bellcore LAMBDANET packet switch. The discussion is then extended to a number of recent proposals for switching fabrics based on this new multiwavelength technology. The particular technologies he discusses are: the photonic knockout switch, a proposal similar to the concept of the LAMBDANET, but not requiring N receivers at each node; the FOX (fast optical cross-connect), an active wavelength routing approach; the ShuffleNet architecture; the HYPASS and BHYPASS switches; the coherent wavelength division lambda switch; and the Bellcore Star-Track multicast switch. >

Multiwavelength networks and new approaches to packet switching

An architecture is presented for an optoelectronic hybrid packet switching system (HYPASS) for the distribution of multiple-bit-rate broadband services. HYPASS is based on an input-buffered/output-controlled arbitration protocol. The internal routing and interconnection utilizes a passive optical transport network with wavelength-tunable laser transmitters and fixed wavelength receivers. The single-stage multiwavelength optical interconnect provides an internally nonblocking network for large throughput routing of the bit-serial optical signals. An internal optical control network, with fixed-wavelength trouble receivers, sends output port information to the input nodes for arbitration and control. Packet buffer storage and control processing is performed by word-parallel electronic circuitry. The characteristics and device requirements for this design are presented along with results of a performance analysis of the arbitration and control protocol. >

HYPASS: an optoelectronic hybrid packet switching system

We propose a new optical muhicast switching system based on a two-phase contention resolution algorithm This architec ture may simultaneously support packet switching, and circuat channel emulation. It can handle time-multiplexed variable bit rate random access packets and reserved access packets in a single framework that incorporates unicast and multicast switching. We present the overall switch architecture, its optical device requirements, and possible implementation schemes. Performance enhancements through the addition of multiple tracks are discussed which indicate the flexibility inherent in this design. Results of an analysis of the throughput and switch performance are discussed.

A broadband optical multicast switch

The authors study the performance of a statistical multiplexer with a common buffer and bursty sources. A uniform arrival and service model has been used to calculate the loss probability as a function of several parameters. It is shown that the ratio of the number of cells in an average burst to buffer capacity per source is a more important parameter than burstiness. When this ratio is much greater than one, performance will be poor unless the load is very low. If the ratio is of the order of one or less, acceptable performance can be achieved. It is shown that combining small load with with multiplexing of many sources can be a very efficient way to lower cell loss probability. >

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Statistical multiplexing of identical bursty sources in an ATM network

A description is given of a broadband packet network architecture suitable for evolving the existing public switching network into an all-fiber broadband network for integrated voice, data, and video applications. The architecture takes into account the needs for bit-rate flexibility, robustness to service evolution, and interoperability with the existing circuit-switched public network. Key features of the network include internally nonblocking broadband packet switches, integrated network transport, and simplified network-routing algorithms. The feasibility and the benefits of a broadband public network using packet technologies are shown. >

W.D. Sincoskie

Papers

A packet network for BISDN applications