Transient anlaysis of a store-and-forward computer-communications network

ABSTRACT

This paper presents the results of a study of transient behavior in a store-and-forward, computer-communications network. The purpose of this paper is to discuss the nature of network performance during severe loading of a network previously operating at steady state conditions. This knowledge is critical since networks are generally designed for a maximum steady state message load. When a transient situation develops, the network may not perform as originally intended and may produce excessive message delay. The primary problem addressed in this paper is the unknown and mathematically intractable relation between the occurrence of a transient traffic load and the resulting performance. The network design and topology are fixed with the experimental factors being the type of transient and the distribution of transient traffic precedence. A five-node, computer-communications network is simulated under two types of transients: first, the effect of a sudden burst of message traffic and second, the effect of a sudden reduction in the interarrival time for a specified period. Also, the effect of the combined transients is investigated. The data is analyzed using ANOVA techniques for a two factor experiment design with four replications per experimental unit. It is concluded that transient message loads have a significant and severe effect on network performance. The degradation in performance persists for a significant period of time. The transient effect is not consistent across each precedence level and erroneous conclusions on average network performance result if the interaction of transient traffic precedence and type of transient are not considered.

REFERENCES

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• 2: Kleinrock, L. (1976). Q_ueueinq Systems Volume II: Computer Applications. John Wiley & Sons, New York.
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INDEX TERMS

Primary Classification:
  C. Computer Systems Organization

Additional Classification:
  C. Computer Systems Organization
  C.2 COMPUTER-COMMUNICATION NETWORKS

  I. Computing Methodologies
  I.6 SIMULATION AND MODELING

General Terms:
Design, Experimentation, Measurement, Performance, Theory