Features of modelling of the information exchange in STI with report Х.25 on the basis absorbing final Markovsky chains and its appendix

The probabilistic-temporal characteristics of multi-packet message delivery over a logical point-topoint channel in a data transmission system with decision feedback are presented. The information exchange procedure between the data transmission equipment is determined by the X.25 protocol. The problem of analyzing the timeliness and reliability of multi-packet messaging in a data transmission system, as well as X.25 protocol key parameter synthesis, which ensures a given information delivery quality, is solved. To accomplish this, mathematical models of the multi-packet message delivery process in the considered data transmission system are constructed taking into account all system parameters of the logical data transmission channel based on absorbing fi nite Markov chains. These models serve as the basis for solving analysis and synthesis problems. On the basis of absorbing fi nite Markov chains, a scientifi c and methodological apparatus is presented that adequately describes the multi-packet messages delivery process in the considered X.25 data transmission system, while situational-bipartite graphs and invariant graphs are used. The developed approach allows us to fi nd the maximum allowable number of retries for each packet while taking into account the client’s requirements regarding the reliability and timeliness of the information delivery.