Routing in multihop packet switching networks: Gb/s challenge

摘要

The authors survey networking solutions that have been proposed for high-speed packet-switched applications. Using these solutions as examples, they identify the specific problems resulting from very high transmission rates and explain how these problems influence the design of high-speed networks and protocols. They conclude that the solutions based on deflection routing are the most promising ones and suggest a number of directions for their evolution. By a packet-switching protocol we mean the network-specific portion of the third OSI layer (i.e., the network layer) of the protocol stack. One part of a packet-switching protocol (according to our definition) is the routing scheme, i.e., the set of rules that assign incoming packets to output links. In general, we can talk about the following three components of the communication subnetwork which are relevant from our point of view: the routing protocol; the congestion-control mechanisms that can be effectively incorporated into the routing protocol; and the network topology. These components are closely related to each other and together offer a single functionality. We discuss routing protocols and congestion-control mechanisms employed in contemporary packet-switched networks, not necessarily in networks operating at very high transmission rates. Then, following some basic definitions related to the topology component, we investigate the challenges posed by the Gb/s transmission rates.