Local Networks and the Internet: From Protocols to Interconnection

Chapter 18

Flow Management

This chapter presents possible evolutions of the Internet network to solve the problems of network congestion and the use of multimedia flows. It explains the mechanisms used to differentiate the treatment of packets, the integration service architecture, RSVP in particular, and the guaranteed classes of services defined by the IntServ working group. This chapter finishes with a presentation of the differentiation services.

18.1. Quality of service

“Quality of service” or QoS is a controversial notion; even if the polemics have calmed down in recent years and some prefer a quality service. Behind this issue is the discussion about the introduction of mechanisms of management for different flow types in the network or the over-dimensioning of the network. In fact, although it is technically and economically possible to add capacity, over-dimensioning is simpler to deploy, albeit not always possible. Wireless networks, such as UMTS, will always have a limited bandwidth and management flow mechanisms are necessary.

This chapter describes how the IETF has defined the cohabitation of new types of data, such as multimedia flows, telephony and distributed games with traditional data (FTP, Web, etc.).

The Internet, as many of the networks, was not initially defined to take QoS parameters into account in packet mode. Packet mode networks were deployed during a time where bandwidth was scarce. The strategy was to get maximum use of the links, even if supplementary ...