This paper analyzes the packet loss and delay performance of an arrayed-waveguide-grating-based (AWG) optical packet switch developed within the EPSRC-funded project WASPNET (wavelength switched packet network). Two node designs are proposed based on feedback and feed-forward strategies, using sharing among multiple wavelengths to assist in contention resolution. The feedback configuration allows packet priority routing at the expense of using a larger AWG. An analytical framework has been established to compute the packet loss probability and delay under Bernoulli traffic, justified by simulation. A packet loss probability of less than 10/sup -9/ was obtained with a buffer depth per wavelength of 10 for a switch size of 16 inputs-outputs, four wavelengths per input at a uniform Bernoulli traffic load of 0.8 per wavelength. The mean delay is less than 0.5 timeslots at the same buffer depth per wavelength.

Packet loss and delay performance of feedback and feed-forward arrayed-waveguide gratings-based optical packet switches with WDM inputs-outputs

Computer networks are undergoing a remarkable transformation. The widespread use of optical fiber to transmit data has made tremendous increases in network bandwidth. Furthermore, greater CPU power, increasing disk capacity, and support for digital audio and video are creating demand for a new class of network services. For example, video-on-demand, distant learning, distant diagnosis, video conferences, and many others applications have popped up one after another in recent years. Many of these services have one thing in common. They all require that the same piece of data be sent to multiple recipients. Even in traditional networks, this operation, called multicasting, can not be handled easily and cheaply. When scaled up to high speed ATM-based networks, the situation could be worse. Multiple streams of data travel around ATM networks. Each tries to send to many different destinations simultaneously. Therefore, designing economical ATM network switches which can support multicasting operations easily is very important in the future generation high speed networks. In the past twelve years or so, many designs for multicasting ATM switches are proposed. It seems about time to do a historical survey. It is hoped that by learning from the wisdom of the previous authors, new spark or angle can be found and exploited to design new multicasting ATM switches. Without easy and inexpensive multicasting, all the exciting services may become unaffordable. This will in turn lead to the diminishing of customer bases and finally will hinder the full-scale deployment of high speed networks.

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Multicast ATM switches: survey and performance evaluation

We present a protocol for controlling a shared ATM multicast tree supporting many-to-many communication The protocol supports one or several ATM virtual channel connections (VCCs) of the many-to-many type The number of VCCs is independent of the number of endpoints The protocol guarantees that there is no interleaving on any VCC of the tree The protocol also guarantees that the traffic contract associated with the VCCs is respected, thus making it possible to use ordinary VCCs of the constant bit rate (CBR), variable bit rate (VBR), or unspecified bit rate (UBR) class No resequencing server or cell buffering inside the network is required, and all cell forwarding is performed at the ATM layer We describe the protocol both informally and formally

SMART: a many-to-many multicast protocol for ATM

This paper introduces a protocol for scheduling of packets in high-capacity switches, termed weighted sequential greedy scheduling (WSGS). WSGS is a simple, greedy algorithm that uses credits to reserve bandwidth for input-output pairs. By using a pipeline technique, WSGS implemented by the current technology readily supports a switching capacity exceeding 1 Tb/s. Admission control is straightforward, allowing bandwidth reservations on a submillisecond time scale. Namely, the central controller readily determines if the newly requested bandwidth can be assigned to the given input-output pair. We have shown that a newly requested bandwidth should be assigned if both the input and output have enough capacity, which requires checking of only two inequalities. Therefore, WSGS is well suited for switching in data networks where sessions might require high bit rates and last for a short time. The WSGS allows bandwidth reservations with fine granularity, e.g., bandwidth can be reserved for individual web sessions, video streams, etc.

Flexible bandwidth allocation in high-capacity packet switches

Principles for designing practical self-routing nonblocking N/spl times/N circuit-switched connection networks with optimal /spl theta/(N/spl middot/log N) hardware at the bit-level of complexity are described. The overall principles behind the architecture can be described as "Expand-Route-Contract". A self-routing nonblocking network with w-bit wide datapaths can be achieved by expanding the datapaths to w+z independent bit-serial connections, routing these connections through self-routing networks with blocking, and by contracting the data at the output and recovering the w-bit wide datapaths. For an appropriate redundancy z, the blocking probability can be made arbitrarily small and the fault tolerance arbitrarily high. By using efficient space domain concentrators, the architecture yields self-routing nonblocking switching networks with an optimal O(N/spl middot/log N) bits of memory or O(N/spl middot/log N/spl middot/log log log N) logic gates. By using a linear-cost time domain concentrator, the architecture yields self-routing nonblocking switching networks with an optimal /spl theta/(N/spl middot/log N) bits of memory or logic gates. These designs meet Shannon's lower bound on memory requirements, established in the 1950s. The number of stages of crossbars can match the theoretical minimum, which has not been achieved by previous self-routing networks. The architecture is feasible with existing electrical or optical technologies. The designs of electrical and optical switch cores with Terabits of bisection bandwidth for Networks-of-Workstations (NOWs) are described.

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Design principles for practical self-routing nonblocking switching networks with O(N/spl middot/log N) bit-complexity

Design Requirements and Architectures for Multicast ATM Switching (Special Issue on Distributed Architecture for Next Generation Communication Networks)

Ken-ichi Yukimatsu

Papers

Design Requirements and Architectures for Multicast ATM Switching (Special Issue on Distributed Architecture for Next Generation Communication Networks)

A Modular Tbit/s TDM-WDM Photonic ATM Switch Using Optical Output Buffers (Special Issue on Photonic Switching Technologies)

Recent Free-Space Photonic Switches (Special Issue on Photonic Switching Technologies)

Analog Free-Space Optical Switch Structure Based on Cascaded Beam Shifters (Special Issue on Photonic Switching Technologies)

Recent Free-Space Photonic Switches