Research On Routing Algorithm For Optical Layer In GMPLS-Based ASON

The Intelligent Optical Network (ION) is the trend of the next generation optical networks. Moreover, the Automatically Switching Optical Network (ASON) has attracted many researchers' interests as a representation of ION. ASON turns to be an intelligent network by implementing a control plane. The control plane can set up and take down a LSP tunnel automatically under the cooperation of GMPLS protocols, and complete the protection and recovery of network failures.According to its functions, ASON is departed into three basic modules: routing, signaling and link management. Because of the newly architecture of ASON, the routing function can't be finished just by routing protocols. In ASON, the routing protocol is responsible for the flooding of network states and resources, just without the routing computation, which is implemented by some constraint-based routing. With GMPLS control, ASON completes the network routing computation through the Constraint-based Routing Modules in GMPLS traffic engineering. Therefore, the constraint-based routing function should guarantee the TE request of users' connections while looking for a shortest path between a source node and a destination node. Hence, the constraint-based routing algorithm is a key part to provide reliable service for connections in ASON.This thesis firstly introduces the concept of ASON and the signaling and routing protocols based on GMPLS. Then it describes RWA problem summarily and shows how to resolve the problem. After that, it analyses the constraint-based routing architecture and routing algorithms in GMPLS traffic engineering. At last, an extended CSPF algorithm based on constraint SRLG is proposed and validated by simulations. The algorithm involves in some traditional QoS parameters like bandwidth, delay, etc. Further, it considers a load-balanced factor that makes the algorithm can find the links with more free bandwidth to use to avoid congestion in some shortest paths because of overload. Thus, the algorithm can provide service that is more reliable. At the same time, the algorithm is extendable. For example, it can lead the user's data flow to some specific nodes and links by involving in the loose explicit routing constraint. The algorithm is simulated on GLASS platform, a network simulator for optical networks.The simulation results validate the algorithm to be right and feasible, especially in reducing the congestion of network and improving the utility of network resources.The thesis has eight chapters as follows.Chapter 1 introduces the concept of ASON, including its development and advantages, explains the source and research meaning of this thesis, then shows the work and innovation of this thesis.Chapter 2 introduces routing and wavelength assignment problem in optical networks, and analyzes the general solution to it.Chapter 3 considers GMPLS signaling protocols for the control plane of ASON and GMPLS extensions to CR-LDP and RSVP-TE.Chapter 4 describes the routing architecture of ASON in detail, including routing differences between IP network and ASON, routing requirement in ASON, routing function modules and extensions to routing protocols for ASON.Chapter 5 introduces the constraint-based routing mechanism in ASON and route computation algorithm based on GMPLS.Chapter 6 shows the architecture of the simulation platform GLASS/SSF, tells how to do simulations on it.Chapter 7 analyses the method of designing CSPF algorithm at first, then proposes an extended CSPF algorithm based on constraint SRLG, and simulates it on GLASS platform at last, which validates the algorithm to be right and feasible. In addition, the chapter shows the simulation results and compares them with other algorithm's performance.Chapter 8 summarizes this thesis, and puts forward some suggestions for the future research.The work is supported by the National Natural Science Foundation of China (90304108).