Traffic overflow in loss systems with selective trunk reservation

We consider two traffic streams competing for service at an n-server queuin g system. Jobs from stream 1, the protected stream, are blocked only if all n servers are busy. Jobs from stream 2, the best effort stream, are blocke d if n - r, r greater than or equal to 1, servers are busy. Blocked custome rs are diverted to a secondary group of c - n servers with, possibly, a dif ferent service rate. For the case r = 1, we calculate the joint probabiliti es of the number of primary and secondary busy servers. For r > 1, we descr ibe a procedure for deriving the joint probabilities. These probabilities a llow for the calculation of various performance measures including the over flow probabilities of the primary server and secondary server group. Our mo del is applicable to traffic control in communication networks that use the selective trunk reservation method. (C) 2000 Elsevier Science B.V. All rig hts reserved.