The Maximum Throughput of a Nonblocking Packet Switch with Window Policy

Dye-Jyun MA

IEICE TRANSACTIONS on Communications   Vol.E80-B       pp.573-580
Publication Date: 1997/04/25
Online ISSN: 
Print ISSN: 0916-8516
Type of Manuscript: Category: Switching and Communication Processing
nonblocking packet switch,  throughput,  head-of-line blocking,  window policy,  

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It is known that in a nonblocking packet switch with input queueing, head-of-line (HOL) blocking affects significantly the maximum throughput of the packet switch. To alleviate the HOL blocking effect, a window policy has been proposed in that each input queue can scan up to a fixed number of packets (called the window size) to select for transmission on the outputs. However, the performance of the window policy has never been precisely characterized. In this paper, we use a closed queueing network model to characterize the performance of the packet switch with window policy. We obtain explicit closed-form formulae for the maximum throughput of the packet switch as a function of the window size. Both balanced and imbalanced traffic patterns are discussed. The formulae can easily determine the effectiveness of the window policy.