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Benchmarking Benchmarking SpaceWire NetworksSpaceWire Networks
Asaf Baron, Isask'har Walter, Ran Ginosar, Isaac Keslassy
EE Department, Technion, Haifa, Israel
Ofer Lapid
Israel Ministry of Defense
International SpaceWire Conference 200717-19 September 2007
The problemThe 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 purposesBenchmark purposes Evaluate protocol proposals Compare network configurations
Cost Performance Reliability
Compare components Formalize requirements Improve the standard
Benchmark ContentsBenchmark 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
End units (examples)End units (examples)
Unit#
Units
# Active Units
Data Handling System (DHS) 2 1
Reconfiguration Unit (RU) 1 1
Solar Cells Control 2 1
Payload Sensor (Camera) 3 1
Downlink 2 1
Star Tracker 3 3
Traffic matrix (examples)Traffic matrix (examples) High bandwidth
From To Type BWB/sec
Latency Recommended
PrioritySensor Storage Payload 100M L
Low bandwidth
DHS Sensor Control 1000 Low H
Evaluating SpaceWire featuresEvaluating SpaceWire features Standard: Packet-level priority (PLP) Non-Standard: N-Char interleaving
(NCI)
N-Char InterleavingN-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 ExampleNo-NCI Example 20181614121086428078767472706866646260585654525048464442403836343230282624220
Red:
Yellow:
Green: 69
Router #1
Router #2
400 Mb/s
100 Mb/s
400 Mb/s
48
26
Delay
NCI Example (4 VC)NCI Example (4 VC)2421.619.216.814.4129.67.24.82.49693.691.288.886.48481.679.276.874.47269.667.264.862.46057.655.252.850.44845.643.240.838.43633.631.228.826.40
Red (26):
Yellow (48):
Green (69):
31
38
45
Router #1
Router #2
400 Mb/s
100 Mb/s
400 Mb/s
Network topologyNetwork topology
DHS
storagesensor
downlink
router
Only active units shown and simulatedRedundant units, routers, links hidden and ignored
Simulations: Low priority payload trafficSimulations: Low priority payload traffic
1. SIMPLE NET
2. ADD PLP
3. ADD NCI
4. NCI+PLP
5. NCI+PLP,more VCs
Simulations Results – Other Simulations Results – Other PrioritiesPriorities
High Priority Medium Priority
NCI with PLP is beneficial Low ETE delay of med+high priority packets High ETE delay of low priority packets