Ciro Aloisio Noronha

Optimum routing of multicast streams

The authors show that the problem of optimally routing multicast streams can be formulated as an integer programming problem. They propose an efficient solution technique, composed of two parts: (i) an extension to the decomposition principle, to speed up the linear relaxation of the problem, and (ii) enhanced value-fixing rules, to prune the search space for the integer problem. They characterize the reduction in run time gained using these techniques. Finally, they compare the run times for the optimum multicast routing algorithm and for existing heuristic algorithms.<<ETX>>

WDM local area networks

Services and possible network topologies are discussed. The technological issues related to the implementation of such topologies are investigated, covering optical transmitters and receivers, tunable lasers and filters, and polarization control. Some experimental implementations reported in the literature are described.<<ETX>>

Experimental PSK/ASK transceiver for the STARNET WDM computer communication network

STARNET is an optical wavelength-division-multiplexed computer communication network that offers each user both a circuit-switched subnetwork and a packer-switched subnetwork. The authors constructed an experimental STARNET node transceiver. The transceiver uses one integrated phase and amplitude modulator to transmit 125 Mb/s amplitude-modulated packet-switched data and 2.488 Gb/s phase modulated circuit-switched data using the same lightwave. The transmitter has an output power of 5 dBm at 1.32 mu m. The receiver recovers the circuit-switched and packet-switched data using heterodyne detection and has a sensitivity of -25 dBm. The resulting system power budget is 30 dB.<<ETX>>

Network Interface Design for Multi-Gbit/s WDM Optical Networks

We report on the design of a distributed, small, fast packet switched network interface that provides electronic buffering and switching for the data channel in reconfigurable multi-Gbps WDM optical networks. The high-speed interface has been constructed and tested in one such WDM network, STARNET, which is based on a physical passive star topology and is intended for backbone applications in Campus Networks. A two-node experimental STARNET is being implemented at the Optical Communications Research Laboratory at Stanford University. The interface prototype was completed in September 1993; the printed circuit board version of the interface has been operational without modification since January 1994. We have since developed software from the driver level to the applications layer.

Routing of Multimedia Streams in Reconfigurable WDM Optical Networks

Multimedia streams have different requirements than those of traditional data traffic, especially in terms of bandwidth; these requirements have to be taken into account when routing such streams. WDM local-area networks with tunable transceivers have an additional degree of freedom over their electronic counterparts: their topology can be dynamically changed. In this paper, we study the problem of routing multimedia streams in WDM networks, taking into account their traffic requirements and making use of the networks ability to dynamically change the topology. We show that the reconfiguration and routing problem can be written as a linear integer programming problem. Since the exact solution to this problem is complex, we present a simpler heuristic, and show that it provides good results, thus obviating the need for the more complicated exact solution. Finally, we evaluate the performance of the WDM network in a realistic traffic scenario, and show that it compares favorably with that of a centralized switch.

Routing of multicast audio/video streams in reconfigurable WDM optical networks

Due to its low attenuation, fiber has become the medium of choice for point-to-point links. Using Wavelength-Division Multiplexing (WDM), many independent channels can be created in the same fiber. A network node equipped with a tunable optical transmitter can select any of these channels for sending data. An optical interconnection combines the signal from the various transmitters in the network, and makes it available to the optical receivers, which may also be tunable. By properly tuning transmitters and/or receivers, point-to-point links can be dynamically created and destroyed. Therefore, in a WDM network, the routing algorithm has an additional degree of freedom compared to traditional networks: it can modify the netowrk topology to create the routes. In this paper, we consider the problem of routing multicast audio/video streams in WDM networks and propose heuristic algorithms to solve it. The performance of these heuristics is evaluated in a number of scenarios, with a realistic traffic model, and from the evaluation we derive guidelines for usage of the proposed algorithms.

A multi-Gbit/s optical LAN utilizing a passive WDM star: towards an experimental prototype

The goals and basic node configuration of STARNET, an optical broadband local area network based on a physical passive star topology, are presented. Over a single physical network, STARNET offers all users both a moderate-speed packet network and a high-speed WDM circuit interconnect. Several topological and protocol solutions based on these two data transport facilities are available to the users. An ongoing experimental effort aimed at the realization of a STARNET prototype is described. The prototype nodes are FDDI and SONET OC-48 data-format-compatible. The first four network layers will be fully implemented and the nodes will serve high performance workstations.<<ETX>>

An experimental multi-Gb/s WDM broadband network

STARNET is an optical broadband network architecture based on a physical passive star topology. Over a single physical network, STARNET offers all users both a moderate-speed packet switched subnetwork and a high-speed wavelength division multiplexing (WDM) circuit switched subnetwork. Based on these two data transport facilities, several topological and protocol solutions are available to the users. As a result, STARNET supports traffic of widely different speed and continuity characteristics. An ongoing experimental effort aimed at the realization of a STARNET prototype at the Optical Communication Research Laboratory of Stanford University is described. The prototype nodes are fiber distributed data interface (FDDI) and synchronous optical network (SONET) OC-48 data rate compatible.<<ETX>>

The evolution of campus networks towards multimedia

The authors consider the problem of providing bandwidth for multimedia services in a campus network. The campus network is composed of a number of subnetworks, interconnected by a backbone. The authors study each subnetwork in isolation, indicating what kinds of topologies should be used as a function of the bandwidth requirement, and then discuss the connection of the subnetwork to the backbone. They also touch upon issues other than the network infrastructure, commenting on the effect of providing multimedia communications on the other layers of the OSI model. Finally, they consider the Stanford Campus Network (SUNET), presenting measurements to characterize its current performance.<<ETX>>

STARNET-E: a broadband wavelength-division multiplexed optical local-area network

We propose enhancements to STARNET, a previously proposed wavelength division multiplexed broadband optical local area network. STARNET offers the users both a medium- speed packet-switched ring network, and a high-speed circuit interconnection. The enhanced architecture, STARNET-E, improves performance in both the packet and the circuit interconnect sections over the previous version. Performance analysis of the STARNET-E packet network shows that this data transport facility can be upgraded to Gb/s total throughput with little added complexity with respect to the original STARNET. Moreover, we show that STARNET nodes can be enhanced to allow reconfigurable multihop topologies with little added optical hardware. The throughput of multihop distributed switching over a passive star physical topology in STARNET-E is compared to the throughput of an active centralized switch. STARNET-E offers to all nodes a Gb/s total throughput packet transport facility and a high speed circuit interconnect, simultaneously and independently. In addition, a node can trade the high speed circuit interconnect service for a multihop broadband packet network without the need for any added optical hardware.