Resequencing in distributed systems with multiple classes

The resequencing problem is considered in a distributed system environment with multiple classes. A system consisting of two parallel heterogeneous M/M/1 queues shared by C different arrival classes is presented and analyzed. Arriving customers are distributed among the two queues according to a probability distribution which depends upon their class. If customers belong to the same class must depart from the server at the same order as they arrived, they incur additional delay called resequencing delay. A recursive solution technique is first introduced to obtain the exact expression for the expected resequencing delay for a single-class case. The result is then extended to the case of a single class with interfering traffic. Some numerical examples are presented to illustrate changes of resequencing delay as a function of distributed loads to servers