The paper presents the architecture and experimentation of a 10-Gb/s QoS-enabled almost-all-optical packet switching system (QOPS) for metro WDM networks. By applying cluster-based wavelength sharing and downsized single-staged optical buffers, QOPS is featured by its highly scalable and cost-effective design. In this paper, we first introduce the switch architecture, system operation, and the key techniques. We describe the in-band header/payload modulation and optical label swapping that is suitable for high-speed optical packet switching. We also present the design of the highly efficient Four-Wave Mixing wavelength converters for packet preemption. We then present an adaptive bifurcated routing (ABR) that directs same-connection packets to different switch clusters according to optimal bifurcation probabilities. Experimental and simulation results demonstrate that QOPS can achieve superior packet-loss performance, QoS differentiation, and minimize traffic blocking probability.
Optical Packet Switching (OPS) has been envisioned as a prominent future optical networking technology for data-centric IP over Wavelength Division Multiplexing (WDM) networks, or optical Internet. Such OPS technology however raises significant transport and Quality of Service (QoS) challenges due to technological limitations. To circumvent OPS limitations, we have proposed a new Optical Coarse Packet Switching (OCPS) paradigm, which uses in-band-controlled per-burst switching and advocates traffic control enforcement to achieve high bandwidth utilization and Quality-of-Service (QoS). Based on OCPS, we have constructed an experimental IP-over-WDM network, referred to as OPSINET. OPSINET consists of two major types of nodes- edge routers, and Optical Label Switched Routers (OLSRs). In this paper, we first introduce the OCPS paradigm. We then present the architecture of OPSINET, describe the in-band header/payload modulation technique, and detail the operations of the edge routers and OLSRs.
This paper consider the design of lightpath Routing and Wavelength Assignment (RWA) problem in Wavelength Division Multiplexing (WDM) networks with or without wavelength conversion. To minimize the required network cost, one has to device as few network devices and take the least network building cost with respect to the required demand requirements. In our model, the required cost including the one to install wavelengths in the network nodes and the building cost to use a specific wavelength in a specified optical link. The problem is formulated as a binary linear programming where the objective function is the minimization of network building cost. Many literatures have pointed out that solving the formulation of this kind is very computationally demanding and heuristic algorithms and/or relaxation techniques are needed for problems with nontrivial size. In this paper, a Lagrangian relaxation based solving procedure is developed for the RWA problem. In particular, We first transfer the RWA problem into a multicommodity integer flow problem using graph transformation technique by adding some artificial network nodes and links with proper cost on them. To achieve minimum network cost, two problem solving phases are developed for networks with and without wavelength converter respectively. In the first phase, we try to optimize the cost of routing without violating the wavelength continuity constraints. If no feasible solutions are obtained in this phase, it means there are no sufficient paths to route lightpaths without wavelength converter. We then take another graph extension with wavelength converter geared to the RWA problem and then applying a shortest path based heuristic algorithm to solve the problem based on the solution obtained from first phase. Two network topologies, GTE network and NSFNET network, are used to evaluate the computational results. Examining the Lagrangian based heuristic results and the lower bounds reveal that the proposed algorithm can efficiently provide a nearly optimal solution for our problem.
SDL is designed for transmission packet data in optical communications. To reduce the complexity of SDL framers, we present a hardware implementation that uses only one CRC detector. In addition, the DC balance operation arithmetic and hardware circuit are derived and integrated into the proposed circuit.
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