Chapter 5 - GMPLS Routing

Abstract

The process known as routing in generalized multiprotocol label switching (GMPLS) is not routing at all, but the distribution of information that is used as the basis of the path computation that determines how label switched paths will be placed within the network. This chapter introduces the concepts of GMPLS routing, focusing on the protocols used and the information distributed. Advanced discussion of what traffic engineering means in a GMPLS network and how paths are computed. GMPLS routing information distribution is based on extensions to Internet Protocol (IP) routing protocols. Traffic engineering information distribution is currently limited to within an IP routing area, because there are two IP routing protocols that interoperate in a scalable way within an area—OSPF and IS-IS—both of these protocols were extended by the internet engineering task force. The chapter introduces the extensions to the protocols in an abstract way before describing how the individual protocols were extended. The chapter gives the briefest of overviews of how the traffic engineering and GMPLS information is carried by the existing routing protocols. The chapter also introduces two advanced features associated with GMPLS routing: graceful shutdown of traffic engineering links and inter-domain routing.