A Novel Routing Strategy for Public, Wide Area ATM Networks

It is highly probable that future Asynchronous Transfer Mode (ATM) networks will be partitioned into several logical (virtual) networks which serve calls belonging to different traffic classes. Because logical networks can be configured quickly and easily, (virtual) network topologies may change frequently as a result of network management intervention, the unpredictability of the topology, combined with unpredictable network element failures and traffic bursts, means that simple, fixed or alternate, routing strategies cannot be used; a dynamic, adaptive routing algorithm is needed. Most conventional adaptive routing algorithms rely on the availability of a database containing information on the current network status. This database is usually replicated in all nodes which calculate routes but may (exceptionally) be housed at a central site within the network. The establishment and maintenance of such a database, particularly if it is distributed, is a difficult task, especially in geographically large networks. The main concern IS keeping the database contents up-to-date so that the routing algorithm is working with accurate data. At regular intervals, or whenever a significant (threshold) change in network status is detected at any node, update messages are flooded through the network to refresh the database contents. The problem is that if the network is operating with economical traffic levels, updates may be frequent and the routing overhead therefore unacceptable. This thesis proposes a new, original routing strategy called Surge Routing which solves the problem in a different way. It is not computationally demanding and does not rely on the existence of a large, time-sensitive, database. It uses controlled flooding to discover truly optimal routes. Separate routing decisions are made for outgoing and incoming paths so that it is possible that different (but optimal) routes will be selected for each direction of transmission. The main advantages of Surge Routing are: 1. it is robust since faulty network elements do not participate in route making decisions; 2. the applied routing strategy can be altered as the network load changes; 3. it is fast because it explores all possible routes in parallel and it is accurate and robust because it uses actual network metrics, not potentially outdated. Hooded update information; 4. the routing function is always aware of the actual network topology, so that routing decisions always produce optimal paths. Simulation results indicate that the traffic overhead generated by Surge Routing is acceptable. The traffic overhead generated by this new routing algorithm is larger than that of conventional adaptive routing techniques under heavy loads, but it is still less than 0.5% of the overall user traffic transmitted on the network. Surge Routing is an adaptive routing technique which can provide better performance than existing routing techniques currently proposed for wide area ATM networks.

Name dc:type.qualificationname

PhD

Level dc:type.qualificationlevel

Doctoral

Grantor dc:publisher.institution

De Montfort University

Year dc:date.issued

1997

Author dc:creator

• Redey, Akos Laszlo

Licence

• https://dora.dmu.ac.uk/bitstreams/9db0071e-d337-4c83-8e4f-fa0f2d370e9a/download