Constraint-Based Routing in the Internet: Basic Principles and Recent Research Ossama Younis and Sonia Fahmy Department of Computer Sciences, Purdue University 250 N
1 Constraint-Based Routing in the Internet: Basic Principles and Recent Research Ossama Younis and Sonia Fahmy Department of Computer Sciences, Purdue University 250 N. University Street, West Lafayette, IN 47907–2066, USA Phone: +1-765-494-6183, Fax: +1-765-494-0739 g E-mail: foyounis,fahmy @cs.purdue.edu Abstract— Novel routing paradigms based on policies, Quality of Service (QoS) requirements. Constraints im- quality of service (QoS) requirements, and packet content posed by policies are referred to as policy constraints, and have been proposed for the Internet over the last decade. the associated routing is referred to as policy routing (or Constraint-based routing algorithms select a routing path policy-based routing). Constraints imposed by QoS re- satisfying constraints which are either administrative- quirements, such as bandwidth, delay, or loss, are referred oriented (policy routing), or service-oriented (QoS routing). The routes, in addition to satisfying constraints, are selected to as QoS constraints, and the associated routing is referred to reduce costs, balance network load, or increase secu- to as QoS routing [1]. rity. In this paper, we discuss several constraint-based rout- ing approaches and explain their requirements, complexity, and recent research proposals. In addition, we illustrate how these approaches can be integrated with Internet label switching and QoS architectures. We also discuss examples of application-level routing techniques used in today’s Inter- net. Keywords—constraint-based routing, QoS routing, policy routing, MPLS, DiffServ, content routing I. INTRODUCTION With the proliferation of Web and multimedia services, and virtual private networks (VPNs) connecting corporate sites, more versatile Internet routing protocols have be- come critical.
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