Journal of High Speed Networks

One of the approaches investigated for multihop lightwave networks is to consider regular graphs as the logical topology for a multihop network. Standard regular topologies are defined only for networks with the number of nodes satisfying some rigid criteria and are not directly usable for multihop networks. Only a few recent proposals (e.g., GEMNET) are regular and yet allow the number of nodes to have any arbitrary value. These networks have one major problem – node addition requires a major redefinition of the network. For example, in a multistar implementation, a large number of retuning of transmitters and receivers and/or renumbering nodes are needed for GEMNET. In this paper we present a new logical topology which has a low diameter but is not strictly regular. The interesting aspect of this topology is that it allows the network to be expanded incrementally involving a relatively small number of edge definitions/redefinitions. In this paper we have described our new topology and its properties. We have also implemented a routing scheme that ensures a low diameter and an algorithm for adding nodes to the network.

Scheduling algorithms for next generation multi Tbit/sec routers and switches are evaluated. Concurrently, available packet interconnections do not exceed a few hundreds Gbit/sec of aggregate throughput, making traffic modeling and computer simulations an extremely important tool. Here, traffic modeling is investigated in terms of arrival process and destination distribution. ‘Real world’ traffic models are proposed, and extensive simulations are carried out and compared to theoretical predictions. It is shown that conventional scheduling algorithms, such as round robin, perform very well under ‘convenient’ simulation assumptions, e.g., heavy load and uniform distribution assumptions. However, when traffic modeling is oriented towards modern applications such as bursty arrival process as in compressed video, or non‐uniform destination distribution as in Internet sites popularity, detailed and quantitative simulation results prove that algorithm performances are significantly degraded from over 95% to less than 60% of maximum throughput. A modified ‘adaptive’ round robin algorithm is proposed, yielding significant improvement of 20% in the router's maximum throughput.

In SONET/WDM networks, one fiber supports multiple wavelengths and each wavelength supports several low rate tributary streams. ‘Traffic grooming’ then is defined as properly using SONET Add/Drop Multiplexer to electronically multiplex and demultiplex required tributary traffic patterns with minimal resource cost (wavelengths and ADMs).

This paper studies traffic grooming problem in single hub SONET/WDM networks and extends existing results. We analyze the real deployments, generalize their results, and study the practical special cases. We prove that BLSR/2 would never be more expensive than UPSR under any traffic pattern. We also present the exact minimum costs of uniform traffic in both UPSR and BLSR/2. We give approximation algorithms for optimal grooming of non‐uniform traffic. Finally, we consider how to select the line speeds if there are two different line speeds available.

In a multi‐service network such as ATM, adaptive data services (such as ABR) share the bandwidth left unused by higher priority services. The network indicates to the ABR sources the fair and efficient rates at which they should transmit to minimize their cell loss. Switches must constantly measure the demand and available capacity, and divide the capacity fairly among the contending connections. In this paper, we propose a new method for determining the “effective” number of active connections, and the fair bandwidth share for each connection. We prove the efficiency and fairness of the proposed method analytically, and use several simulations to illustrate its fairness dynamics and transient response properties.