Concurrent round-robin dispatching scheme in a Clos-network switch

Eiji Oki, Zhigang Jing, Roberto Rojas-Cessa, H. Jonathan Chao

Research output: Contribution to journalArticlepeer-review

18 Scopus citations


A Clos-network switch architecture is attractive because of its scalability. Previously proposed implementable dispatching schemes from the first stage to the second stage, such as random dispatching, are not able to achieve a high throughput unless the internal bandwidth is expanded. This paper proposes a concurrent round-robin dispatching (CRRD) scheme for a Clos-network switch, to overcome the throughput limitation of the random dispatching scheme. The CRRD scheme provides high switch throughput without expanding internal bandwidth. CRRD implementation is very simple because only simple round-robin arbiters are adopted. In CRRD, the round-robin arbiters concurrently perform the matching between requesting cells and output links in each first-stage module to dispatch the cells to available second-stage modules. We show that CRRD achieves 100% throughput under uniform traffic. When the offered load reaches 1.0, the pointers of round-robin arbiters at the first-stage and second-stage modules are effectiv ely desynchronized and contention is avoided.

Original languageEnglish (US)
Pages (from-to)107-111
Number of pages5
JournalIEEE International Conference on Communications
StatePublished - 2001
Externally publishedYes

All Science Journal Classification (ASJC) codes

  • Computer Networks and Communications
  • Electrical and Electronic Engineering


  • Arbitration
  • Clos-network switch
  • Dispatching
  • Packet switch
  • Throughput


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