Waveband routing and wavelength assignment (WRWA) has only recently attracted attention from the optical networking industry for its practical importance in reducing the control complexity and cost of optical cross-connects (OXCs). In this paper, we study WRWA tasks in hybrid hierarchical wavelength division multiplexing (WDM) networks with OXCs that can route multiple granularity (wavelengths and wavebands) at the same time. We develop a unique integer linear programming (ILP) model of a network with those OXCs with the objective to minimize the cost of optical-electronic-optical (OEO) and all optical (OOO) ports used. The optimal ILP solution can only be obtained for networks of smaller size. For larger problems we use a heuristic WRWA algorithm which was presented in our earlier work. Simulation results in this paper show near optimal performance of the heuristic WRWA algorithm for networks of smaller size.

We study routing and wavelength assignment (RWA) tasks in WDM mesh networks with wavelength conversion capabilities. For each lightpath request, we solve the routing and wavelength assignment sub-problems as a single problem, rather than separating them into two separate problems. We use four different optimization criteria: (1) minimum number of wavelength conversions; (2) minimum number of wavelengths used; (3) minimum hop count; (4) minimum use of scarce resources (trunking). Each of these problems is solved by a Dijkstra type of algorithm, executed sequentially on one request at a time. We also develop an integer linear programming (ILP) model with the objective of minimizing the number of wavelength conversions. The optimal ILP solution can only be obtained for small networks. We conduct a comprehensive simulation study of the performance of the algorithms for different network topologies and traffic scenarios.

Recently, a new global open Ethernet (GOE) architecture was proposed as a cost-effective scalable solution for the next generation of VPNs over an optical network infrastructure. In this paper, we present a traffic engineering design for networks that support the GOE architecture. The current extensions of the spanning tree protocol (STP), such as rapid spanning tree (RST) and multiple spanning tree (MST), use a link cost metric which is inversely proportional to the link capacity. In order to achieve a better load balancing in the network, we propose to use the link cost metric which is a function of the current link load. The traffic engineering algorithms presented in this paper use two different link cost functions. We comment on the performance of those heuristic algorithms for various network topologies and under several traffic scenarios. Our results demonstrate a significant improvement in the network utilization when the link cost metric is a function of the link load compared to the case when it is inversely proportional to the link capacity.

In this paper, we study the routing and wavelength assignment (RWA) tasks in WDM mesh networks with wavelength conversion capabilities. We solve the routing and wavelength assignment sub-problems as a single problem, rather than separating them into two separate problems. We use two different optimization criteria: (1) minimize the number of wavelength conversions used; and (2) minimize the number of wavelengths used. Each of these problems is solved by using a method based on the Dijkstra algorithm, sequentially on one connection at a time. We study and comment on the performance of the algorithms for different network topologies and traffic scenarios.

In this paper we propose a mew greatly scheduling algorithm for crossbar terabit routers with virtual output queuing (VOQ) at input ports. The proposed global and dynamic round-robin (GDRR) scheduler is pipelined scheduler. Our empirical studies show that: 1) the scheduler provides minimum service rate (MSR) guarantees for high-priority confirming traffic, 2) by using the global round-robin method available bandwidth at any output port is fairly shared among input ports (the input port fairness), and 3) by using the dynamic round-robin method available bandwidth at any input port is fairly shared among VOQs (the output port fairness). Increasing the number of scheduling modules linearly increases the latency of the scheduler, while increasing the number of supported traffic classes does not affect its design.

We present a control-theoretic approach to the design of closed-loop rate-based flow control in high-speed networks. The proposed control uses a dual proportional-plus-derivative controller, where the control parameters can be designed to ensure the stability of the traffic patterns and propagation delays. We show how the control mechanism can be used to design a controller to support ABR service based on feedback of explicit rates (ERs). We demonstrate the excellent transient and steady-state performance of the controller through a number of examples. We also show experimental results that have been obtained from our asynchronous transfer mode (ATM) testbed, which consists of two interconnected ATM LANs, one located in Princeton, NJ, and the other in Berlin, Germany, with an all-software ER-controller implementation.

We present a control theoretic approach to the design of closed loop rate based flow control in high speed networks. The proposed control uses a dual proportional derivative controller, where the control parameters can be designed to ensure the stability of the control loop in a control theoretic sense, over a wide range of traffic patterns and propagation delays. We show how the control mechanism can be used to design a controller to support available bit rate (ABR) service based on feedback of explicit rates. We demonstrate the excellent transient and steady state performance of the controller through a number of examples.

In Part I, we proposed a distributed, state dependent, dynamic routing method, called least cost routing in multi-service networks (LCRM), for multirate circuit-switched broadband ISDN networks, which support a variety of traffic classes with different characteristics. This method represents the one-step policy improvement on a chosen base policy. As a base policy /spl pi//sub 0/, we use the policy which allows direct link routing only. The policy /spl pi//sub 0/ also requires that each call class has a portion of link bandwidth dedicated to it. The task is to find an efficient computational way to obtain the corresponding relative cost values, which represent costs of routing a call over one link. We consider the one-link model with two types of traffic. Our main result is that the system of linear equations associated with the two-dimensional Markov chain can be decomposed into several systems of linear equations, each one associated with the one-dimensional Markov chain.

The problem of dynamic routing in multiple-service networks is studied. The authors consider a multirate circuit-switched broadband ISDN network that supports a variety of traffic classes with different traffic characteristics (bandwidth requirement, call arrival rate, and call holding time) and reward parameter. The task is to find a dynamic routing method which minimizes the long-run average cost of lost calls. Markov decision theory, with the objective of an average cost optimization is appropriate to the solution of this problem. Using this approach, they propose a distributed, state dependent, dynamic routing method which they call least cost routing in multiple-service networks (LCRM). They define a base policy such that the corresponding relative cost function associated with the Howard (1960) policy improvement routine of Markov decision theory is easily computed. This function is then used to determine the one-step policy improvement (LCRM).>