This paper considers the problem of grooming multicast traffic in WDM networks, with arbitrary mesh topologies. The problem is different from grooming of unicast traffic, since traffic can be delivered to destinations through other destinations in the same set, or through branching points. The paper presents an optimal Integer Linear Programming (ILP) formulation in order to minimize the cost of the network in terms of the number of SONET Add/Drop Multiplexers (ADM). The formulation also minimizes the number of wavelength channels used in the network, and does not allow bifurcation of traffic. Since the ILP formulation is able to solve limited size problems, the paper also introduces a heuristic approach to solve the problem.
KEYWORDS: Receivers, Internet, Computer simulations, Floods, Computer engineering, Control systems, Alternate lighting of surfaces, Signal detection, Switches, Head
The Transmission Control Protocol (TCP), provides flow control functions which are based on the window mechanism. Packet losses are detected by various mechanisms, such as timeouts and duplicate acknowledgements, and are then recovered from using different techniques. A problem that arises with the use of window based mechanisms is that the availability of a large number of credits at the source may cause a source to flood the network with back-to-back packets, which may drive the network into congestion, especially if multiple sources become active at the same time. In this paper we propose a new approach for congestion reduction. The approach works by shaping the traffic at the TCP source, such that the basic TCP flow control mechanism is still preserved, but the packet transmissions are spaced in time in order to prevent a sudden surge of traffic from overflowing the routers' buffers. Simulation results show that this technique can result in an improved network performance, in terms of reduced mean delay, delay variance, and packet dropping ratio.
In this paper we present a control channel-based modular switching technique for packet transport over next-generation high-speed dense- wavelength division multiplexed (DWDM) networks. The proposed technique reduce electronic processing bottleneck in DWDM networks by sending routing information on a dedicated control channel in the form of pilot control packets. The pilot control packets are processed electronically by a control processor at each intermediate node. Processing of pilot control packets ensures that the data packets propagate from source to destination in photonic form (that is, without any processing by intermediate nodes). In the proposed switch, different modules perform different functions. The modular nature of the proposed switch enables that each module can be implemented in any available technology. Thus, with the technology improvements, individual modules can be upgraded as compared to replacing the whole switch. The performance evaluations of the proposed technique show that 3x reduction in processing requirements can be achieved for a 100 channel DWDM-based long haul network. This reduction in processing requirements translates into 2x reduction in hardware cost. Furthermore, the proposed technique provides a large saving in terms of electrical-to-optical and optical-to-electrical converters cost per node. This saving in processing reduction can be leveraged to provide more bandwidth to the services.
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