An algorithm for constructing and adaptively maintaining routing tables in communication networks is presented. The algorithm can be employed in message as well as circuit switching networks, uses distributed computation, provides routing tables that are loop-free for each destination at all times, adapts to changes in network flows, and is completely failsafe. The latter means that after arbitrary failures and additions, the network recovers in finite time in the sense of providing routing paths between all physically connected nodes. For each destination, the routes are independently updated by an update cycle triggered by the destination.

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A Failsafe Distributed Routing Protocol

An algorithm that provides minimum delay routing in a data communication network using virtual line-switching is presented. The algorithm uses distributed computation in the sense that the nodes of the network update their information in an orderly fashion based on messages received from their neighbors. Receipt of these messages also triggers the various steps of the update and rerouting, so that these operations are performed in appropriate sequencing. For stationary input requirements and fixed topology the algorithm reduces network delay at each step and provides loop-free routing in the network. The method also provides an algorithm for quasi-static routing, when the input flows are slowly changing.

/pdf/optimal-distributed-routing-for-virtual-line-switched-data-3c8zbdcy1p.pdf

Optimal Distributed Routing for Virtual Line-Switched Data Networks

A distributed adaptive routing algorithm

: Iterative protocols for adaptive routing in line and message switched data communication networks are presented in this thesis. Distributed computation is used in the sense that each node in the network bases all its decisions on control messages received only from its neighbors. Thus, each node in the network determines individually onto which of its outgoing links to send the flow, addressed to a specific destination. The control messages exchanged between neighbors contain information about network connectivity, network congestion and link failures. Loop-free routing for each destination is maintained in the network at all times. Generally, prevention of loops results in saving resources and reduction in delay. In addition, loop-free routing establishes a partial ordering on the set of nodes of the network. The latter property is extensively utilized throughout this work. failsafe and deadlock-free operation of the protocols is guaranteed, meaning that after arbitrary failures and additions of links and nodes, the network recovers in finite time. Recovery means that routing paths are provided between all connected nodes. For stationary input traffic statistics and fixed topology the protocols are optimal. they reduce network delay at each iteration and minimum average delay over all routing assignments is obtained in steady-state.

Adrian. Segall

Papers

Failsafe distributed optimal routing in data-communication networks