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Two-Stage Switch. High-Performance Networking Group Isaac Keslassy, Nick McKeown. Scheduler. inputs. outputs. Input-Queued Packet Switch. Crossbar. 1. N. 1. N. Round-Robin Scheduling. Uniform & non-bursty traffic => 100% throughput Problem: traffic is non-uniform & bursty. 1. 1.
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Two-Stage Switch High-Performance Networking Group Isaac Keslassy, Nick McKeown
Scheduler inputs outputs Input-Queued Packet Switch Crossbar 1 . . . . N 1 . . . . N
Round-Robin Scheduling • Uniform & non-bursty traffic => 100% throughput • Problem: traffic is non-uniform & bursty
1 1 1 N N N Two-Stage Switch (I) External Inputs Internal Inputs External Outputs First Round-Robin Second Round-Robin [C.S.Chang et al.: http://www.ee.nthu.edu.tw/~cschang/PartI.pdf]
1 1 1 N N N Load Balancing Two-Stage Switch (I) External Inputs Internal Inputs External Outputs First Round-Robin Second Round-Robin [C.S.Chang et al.: http://www.ee.nthu.edu.tw/~cschang/PartI.pdf]
1 1 1 N N N Two-Stage Switch (I) External Inputs Internal Inputs External Outputs First Round-Robin Second Round-Robin • No scheduling • Problem: unbounded mis-sequencing
Two-Stage Switch (II) New N3 instead of N2 [Infocom’02 paper: http://klamath.stanford.edu/~keslassy/tmp/two-stage.pdf]
Current Work • Practical implementation of this scheme • Statistical bounds on mis-sequencing • Queue length distributions • TCP properties
Phase 1 An optical two-stage switch 1 Phase 2 2 3