Performance comparison of routing algorithms in packet switched networks

The algorithms are (1) the CODEX algorithm, (2) Gallager´s distributed algorithm (1977), and (3) the well-known ARPANET algorithm. The essential characteristics and critical issues in these algorithms are identified through experimentation under a variety of traffic and network operating conditions. The sensitivity of the mean delay performance of the algorithms to operating parameters, such as the routing update period and the traffic adjustment parameters, are examined. The comparison of mean delay behavior indicates that under stationary traffic conditions, gradient-based algorithms, such as Gallager´s algorithm, outperform the other algorithms, whereas the CODEX algorithm, which is a shortest-path-based virtual circuit routing algorithm, does better in quasistatic traffic conditions. The ARPANET algorithm performs poorly, compared to the above two algorithms under moderate to heavy loading conditions. Some of the factors which could be contributing to the poor performance of the ARPANET algorithm are examined