A Multi-Plane Packet Switch Based on Combined Packet Distribution and Hierarchical Priority Scheduling

Norihiko MORIWAKI  Hidehiro TOYODA  Masayuki TAKASE  

IEICE TRANSACTIONS on Communications   Vol.E87-B   No.7   pp.1977-1983
Publication Date: 2004/07/01
Online ISSN: 
Print ISSN: 0916-8516
Type of Manuscript: PAPER
Category: Switching
tera bit,  multi-plane,  packet switch,  combined packet,  distribution,  hierarchical scheduling,  

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A large-scale packet-switch architecture for a tera bit/s system--which uses a combined-packet-distribution (CPD) method for a crossbar packet switch--was developed. This method eliminates the restriction on scheduling processing time by extending a switching data unit. The data unit is called a combined packet that consists of plural variable-length packets or their fragments. The combined packets are sequentially distributed among multiple crossbar switch planes and their sequence integrity is preserved. Distributive targets among the switch planes are selectable. As a result, when one or more switch planes are damaged, redundancy of the switch fabric is easily attained in a so-called "graceful degradation" manner. Moreover, this switch uses a novel algorithm called hierarchical priority scheduling. This algorithm enables fairness of scheduling by taking account of queuing state. The repetition required for priority scheduling is reduced by a novel hierarchical approach. The simulated performance of this algorithm shows that it performs better than the simple maximal matching method under both uniform and non-uniform traffic.