International Space. Wire Conference 2007 17 -19 September 2007 Benchmarking Space. Wire Networks Asaf Baron, Isask'har Walter, Ran Ginosar, Isaac Keslassy EE Department, Technion, Haifa, Israel Ofer Lapid Israel Ministry of Defense January 2007 Optimal Optical Routers
The problem n Multiple proposals for Space. Wire Vendors design new Space. Wire parts n BUT … n n n How can we evaluate proposals? How can we compare parts from different vendors?
Benchmark
Benchmark purposes n n Evaluate protocol proposals Compare network configurations n n n Cost Performance Reliability Compare components Formalize requirements Improve the standard
Benchmark Contents n End units n n Redundancy Traffic specifications n n Unit X sends to unit Y Quality of Service Requirements n n Bandwidth, real time constraints, deadlines, Priorities, etc. Benchmark does NOT include implementation details n No topology, no specific components
End units (examples) Unit # # Active Units Data Handling System (DHS) 2 1 Reconfiguration Unit (RU) 1 1 Payload Sensor (Camera) 3 1 Downlink 2 1 Solar Cells Control 2 1 Star Tracker 3 3
Traffic matrix
Traffic matrix (examples) n High bandwidth From Sensor n To Type BW B/sec Storage Payload Latency 100 M Recommended Priority L Low bandwidth DHS Sensor Control 1000 Low H
Using the Benchmark
Evaluating Space. Wire features n n Standard: Packet-level priority (PLP) Non-Standard: N-Char interleaving (NCI)
N-Char Interleaving n n Not in Space. Wire standard But, Very useful in Wormhole networks Requires multiple VCs VC code added to each N-Char n Ideally, SPW would allow longer flits
No-NCI Example 22 24 26 28 30 32 34 36 38 40 42 44 46 48 50 52 54 56 58 60 62 64 66 68 70 72 74 76 78 80 20 10 12 14 16 18 0 2 4 6 8 100 Mb/s Delay Red: 26 Yellow: 48 Green: 69 400 Mb/s Router #1 Router #2 400 Mb/s
NCI Example (4 VC) Delay 26. 4 28. 8 33. 6 38. 4 40. 8 43. 2 45. 6 50. 4 52. 8 55. 2 57. 6 62. 4 64. 8 67. 2 69. 6 74. 4 76. 8 79. 2 86. 4 88. 8 93. 6 31. 2 81. 6 91. 2 14. 4 16. 8 19. 2 21. 6 2. 4 4. 8 7. 2 9. 6 36 48 60 72 84 96 24 12 0 100 Mb/s Red (26): 31 Yellow (48): 38 Green (69): 45 400 Mb/s Router #1 Router #2 400 Mb/s
Network topology downlink DHS router sensor storage Only active units shown and simulated Redundant units, routers, links hidden and ignored
Simulator display n n Simulated using OPNET A commercial simulator for networks
Simulations: Low priority payload traffic 1. SIMPLE NET 4. NCI+PLP 2. ADD PLP 5. NCI+PLP, more VCs 3. ADD NCI
Simulations Results – Other Priorities High Priority n Medium Priority NCI with PLP is beneficial n n Low ETE delay of med+high priority packets High ETE delay of low priority packets
Summary n n n A new Space. Wire benchmark (open source) A new simulator for Space. Wire An example of using the benchmark Priorities help Non-standard NCI helps even more
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