Constrained Routing Of Traffic Engineering-oriented Research And Implementation

With the rapid growth of web applications, multimedia applications and data flows, the traditional best-effort routing mechanism faces great challenge. Current IGP, such as OSPF or IS-IS protocol, is routing over shortest paths. Moreover, it does not take the requirement of traffic and present utilization of network resource into account. Thus the traffic can not be distributed optimally and the congestion rate is high. As a result, how to provide QoS guarantees and optimize the performance of the network has become a key issue in research. In order to improve the utilization of network resource, minimize congestion and enhance the capability of the network, IETF has proposed Traffic Engineering. The primary objective of Traffic Engineering is to control the mapping and distribution of traffic over the existing network infrastructure to assure satisfactory service delivery, to maximize throughoutput of network, and to optimize resource utilization. Constraint-Based Routing is one of the key mechanisms to achieve Traffic Engineering.This thesis emphasizes Constraint-Based Routing, Traffic Engineering and relating technologies. By combining the extension of OSPF protocol, Constraint-Based Routing, MPLS and RSVP, we design and implement the prototype. The main contents of the thesis are as follows:After analyzing the existing problems of traditional routing/switching system, we introduce Traffic Engineering and Constraint-Based Routing, discuss the Traffic Engineering mechanisms as well as relating technologies, and survey the important routing algorithms for Traffic Engineering. All algorithms are classified into two categories: IP-based and MPLS-based. What's more, the essence of algorithms and comparisons among them are given.We research Constraint-Based Routing and its two components: QoS-routing and Policy-routing. Moreover, in order to implement Traffic-Engineering oriented Constraint-Based Routing, we propose"Dynamic Link Cost Tuning"mechanism, GMSP (Greedy Multi-Shortest Path) algorithm and"Minimizing Maximum Link Utilization"linear programming model. After that, we design the model of Constraint-Based Routing and its key components.Based on in-depth analysis of OSPF protocol, we implement OSPF-TE, which constrains the distribution and parsing mechanism of TE-LSA and Traffic Engineering database. It provides Constraint-Based Routing with necessary information. Then, by using"Dynamic Link Cost Tuning"mechanism, GMSP algorithm,"Minimizing Maximum Link Utilization"model and Linux policy-routing, we develop online Constraint-Based Routing, offline Constraint-Based Routing and policy-routing. These three components constitute Constraint-Based Routing.Furthermore, we study MPLS and RSVP thoroughly. Also we make use of RSVP to distribute the label of MPLS in order to mapping route computed by Constraint-Based Routing to LSP tunnel, which is used to transfer traffic of network.We design and implement the prototype. In addition, the feasibility and the effectiveness of the prototype are proved through well-chosen experiments. The results show that the prototype works much more efficient than traditional routing/switching system.The research work in this thesis is supported by Science Foundation of Jiangsu Province project"High Performance Networking Routing/Switching System with Algorithm and Protocol Research", 2001.12-2004.10 (BK2001205).