Wide-sense Nonblocking for 3-stage Clos Networks

Part of the Network Theory and Applications book series (NETA, volume 5)


Let C,(n,m,r) denote the symmetric 3-stage Clos network with r n × m crossbars in the first and third stage, and m r × r crossbars in the second stage. A network is wide-sense nonblocking if it is nonblocking under a given routing algorithm. Packing is a routing algorithm much heralded in the folklore, and was shown to save n/2 center switches for r = 2. We prove the surprising result that packing does not save anything for r ≥ 3. We also show that C (n,m,r) is not wide-sense nonblocking (under any algorithm) for r ≥ 3 if m < [7n/4]. We also extend some results to asymmetric 3-stage Clos networks


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Copyright information

© Kluwer Academic Publishers 2001

Authors and Affiliations

  1. 1.Department of Computer Science and EngineeringUniversity of MinnesotaMinneapolisUSA
  2. 2.AT&T Shannon LaboratoryFlorham ParkUSA
  3. 3.Lattice Semiconductor CorpMilpitasUSA
  4. 4.Department of MathematicsChiao Tung UniversityHsinChuTaiwan, ROC

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