Buffer requirements and server ordering in a tandem queue with correlated service times

We analyze the intermediate buffer requirements in a tandem queue where ser vice times of each customer are deterministically correlated between the se rvers and arbitrarily distributed between customers. The major issue at han d is the determination of intermediate buffer sizes assuring no blocking wh en the arrivals pattern is arbitrary and unpredictable. The analysis shows that the worst arrival process is the Just-in-Time (JIT) process. Further, it shows that ordering of the servers with respect to service rates may be detrimental. and that the most vulnerable architectural design is that in w hich the servers have almost the same service rates. It is shown that the t otal buffer requirement in the system may be quite sensitive to the server ordering: A proper ordering requires just O(M) (where M is the number of qu eues) buffer size, while an improper ordering may require O(M-2).