170 likes | 267 Views
Scheduling Proposals. Scheduling Group Giulio Galante, Wensheng Hua, Sundar Iyer, Isaac Keslassy, Pablo Molinero, Gireesh Shrimali, Rui Zhang. Round-Robin. Non-Round-Robin. Two-Stage Switch (I). Longer Packets. Two-Stage Switch (II). Scheduler. inputs. outputs.
E N D
Scheduling Proposals Scheduling Group Giulio Galante, Wensheng Hua, Sundar Iyer, Isaac Keslassy, Pablo Molinero, Gireesh Shrimali, Rui Zhang
Round-Robin Non-Round-Robin Two-Stage Switch (I) Longer Packets Two-Stage Switch (II)
Scheduler inputs outputs Input-Queued Packet Switch Crossbar 1,1 1 i,j . . . . N N,N 1 . . . . N
Round-Robin: main properties • Simple to implement • 100% throughput with uniform traffic Bad throughput with non-uniform traffic
Non-Round-Robin Scheduling Too complex with a 100 Tbps router • Computation complexity: • Cell time = 64 B /160 Gbps = 3.2 ns = one clock cycle (today, 50 ns ; MWM: N3) • Ports: 625(today, 32) • Communication complexity • Number of bidirectional links: 625(today, 170) • Information flow rate: 0.3 Gcells/s x 20 b/cell = 6 Gbps(today, 2.5Gbps) Up to 100% throughput
Round-Robin Simple| No 100% throughput Non-Round-Robin 100% throughput| Complex Two-Stage Switch (I) Longer Packets Two-Stage Switch (II)
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]
Two-Stage Switch (I): main properties • Simple to implement • 100% throughput • Possibility of using two sides of same mirrors Mis-sequencing!
Two-Stage Switch (II) New N3 instead of N2 [Paper under review: http://klamath.stanford.edu/~keslassy/tmp/two-stage.pdf]
Two-Stage Switch (II): main properties • No missequencing • 100% throughput • Low average delay (within a bound from “optimal” output-queued switch) Idea not thoroughly studied: difficult implementation?
Round-Robin Simple| No 100% throughput Non-Round-Robin 100% throughput| Complex Two-Stage Switch (I) Longer Packets 100% throughput, simple| Missequencing Two-Stage Switch (II) 100% throughput, no missequencing|Implementation?
Longer packets Variable-size packets [Tassiulas et al.: http://www.glue.umd.edu/~koushik/hoti00-kkar.ps.gz]
Round-Robin Simple| No 100% throughput Non-Round-Robin 100% throughput| Complex Two-Stage Switch (I) Longer Packets 100% throughput, simple| Missequencing 100% throughput, more time between computations| Implementation? Two-Stage Switch (II) 100% throughput, no missequencing|Implementation?
(100x100) (100x100) 2. Multistage Networks Banyan Network (2x2) 2 Layers of kxk switches