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International SpaceWire Conference 2007 17-19 September 2007. Benchmarking SpaceWire Networks. Asaf Baron, Isask'har Walter, Ran Ginosar, Isaac Keslassy EE Department, Technion, Haifa, Israel Ofer Lapid Israel Ministry of Defense. The problem. Multiple proposals for SpaceWire
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International SpaceWire Conference 2007 17-19 September 2007 Benchmarking SpaceWire Networks Asaf Baron, Isask'har Walter, Ran Ginosar, Isaac Keslassy EE Department, Technion, Haifa, Israel Ofer Lapid Israel Ministry of Defense
The problem • Multiple proposals for SpaceWire • Vendors design new SpaceWire parts • BUT … • How can we evaluate proposals? • How can we compare parts from different vendors?
Benchmark purposes • Evaluate protocol proposals • Compare network configurations • Cost • Performance • Reliability • Compare components • Formalize requirements • Improve the standard
Benchmark Contents • End units • Redundancy • Traffic specifications • Unit X sends to unit Y • Quality of Service Requirements • Bandwidth, real time constraints, deadlines, Priorities, etc. • Benchmark does NOT include implementation details • No topology, no specific components
Traffic matrix (examples) • High bandwidth • Low bandwidth
Evaluating SpaceWire features • Standard: Packet-level priority (PLP) • Non-Standard: N-Char interleaving (NCI)
N-Char Interleaving • Not in SpaceWire standard • But, Very useful in Wormhole networks • Requires multiple VCs • VC code added to each N-Char • Ideally, SPW would allow longer flits
Delay No-NCI Example 20 18 14 62 10 8 6 4 12 80 78 76 74 72 70 68 66 2 64 52 16 58 56 54 50 48 60 44 42 40 38 46 34 32 30 28 26 24 36 22 0 100 Mb/s Red: 26 Yellow: 48 Green: 69 400 Mb/s Router #1 Router #2 400 Mb/s
Delay NCI Example (4 VC) 24 21.6 16.8 74.4 12 9.6 7.2 4.8 14.4 96 93.6 91.2 88.8 86.4 84 81.6 79.2 2.4 76.8 62.4 19.2 69.6 67.2 64.8 60 57.6 72 52.8 50.4 48 45.6 55.2 40.8 38.4 36 33.6 31.2 28.8 43.2 26.4 0 100 Mb/s Red (26): 31 Yellow (48): 38 Green (69): 45 400 Mb/s Router #1 Router #2 400 Mb/s
DHS storage Network topology downlink router sensor Only active units shown and simulated Redundant units, routers, links hidden and ignored
Simulator display • 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 • NCI with PLP is beneficial • Low ETE delay of med+high priority packets • High ETE delay of low priority packets Medium Priority
Summary • A new SpaceWire benchmark (open source) • A new simulator for SpaceWire • An example of using the benchmark • Priorities help • Non-standard NCI helps even more