Queueing Systems

, Volume 60, Issue 3–4, pp 271–288 | Cite as

Queues where customers of one queue act as servers of the other queue

  • Efrat Perel
  • Uri YechialiEmail author


We consider a system comprised of two connected M/M/•/• type queues, where customers of one queue act as servers for the other queue. One queue, Q 1, operates as a limited-buffer M/M/1/N−1 system. The other queue, Q 2, has an unlimited-buffer and receives service from the customers of Q 1. Such analytic models may represent applications like SETI@home, where idle computers of users are used to process data collected by space radio telescopes. Let L 1 denote the number of customers in Q 1. Then, two models are studied, distinguished by their service discipline in Q 2: In Model 1, Q 2 operates as an unlimited-buffer, single-server M/M/1/∞ queue with Poisson arrival rate λ 2 and dynamically changing service rate μ 2 L 1. In Model 2, Q 2 operates as a multi-server M/M/L 1/∞ queue with varying number of servers, L 1, each serving at a Poisson rate of μ 2.

We analyze both models and derive the Probability Generating Functions of the system’s steady-state probabilities. We then calculate the mean total number of customers present in each queue. Extreme cases are indicated.


Connected 2-queue systems Customers act as servers Markovian queues 

Mathematics Subject Classification (2000)



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Copyright information

© Springer Science+Business Media, LLC 2008

Authors and Affiliations

  1. 1.Department of Statistics and Operations Research, School of Mathematical SciencesTel Aviv UniversityTel AvivIsrael
  2. 2.Afeka Academic College of EngineeringTel AvivIsrael

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