ESA UNCLASSIFIED – For Official Use – Privileged
Status of the ECSS-ST-50-12C Rev.1 standardisation process
David Jameux ESTEC 11/04/2013
ECSS-ST-50-12C Rev.1 status | David Jameux | ESTEC | 11/04/2013 | TEC-ED | Slide 2
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Background – CR as processed by the SpW Working Group
1. Based on the 54 Change Requests a. Posted by SpW community (mainly SpW WG) b. Processed in details and in length by the SpW WG (thanks!)
2. Most of them technically closed a. Ready to be standardised
3. A few of them still open a. Needed technical work
ECSS-ST-50-12C Rev.1 status | David Jameux | ESTEC | 11/04/2013 | TEC-ED | Slide 3
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Scope
4. Number
5. Location of deficiency
clause page
(e.g. 3.1 14)
6. Changes 7. Justification 8. Disposition
3 Whole document
all Clarify definition and behaviour of “nodes” and review all node-related requirements. The term node should be only used as abstract end point (terminal) of the network and not for a physical unit.
Introduce a different term (e.g. device) for electronic modules or units in the network which can contain one or more SpaceWire interfaces.
Introduce a single configuration ports for devices and the permission to contain a routing capability.Remove a number of ambiguities raised by the SpW users (mainly the Working Group).
As reported in [3], [4], [94], [95], [98] and [100]:
Some requirements in ECSS-E-ST-50-12C refer to the term “node” as some electronic module or unit comprising one or several SpW interfaces while other requirements refer to the term “node” as the SpW interface itself as a terminal of the network. This has been creating a lot of confusion, specifically when trying to define other protocols operating on top of SpaceWire.
Amongst the related confusion is the Time-code usage in particular and time distribution in general, which is severely impacted by the definition of a “node”.
Another source of confusion is whether a packet with unexpected destination address shall be discarded, since RMAP does not follow this rule.
Moreover, the design of SpaceWire higher level protocols such as Plug-And-Play require a clear definition of items to be discovered in a SpW network, and the assignment of a configuration port to each of these items.
At last, some discussion in the SpW WG is ongoing whether aligning the definition of nodes to the one of routers (with e.g. the possibility for nodes to switch characters/packets) would clarify this definition and help supporting PnP.
Clarify the terms “port”, “link”, interface”, “router”, “node”, “end-point”, etc. w.r.t. SpaceWire as part of the revision of the standard.
4 Whole document
all Carefully improve the protocol description and consistency formalism (clear layering) and precise the use of some terms (e.g. switching instead of routing) and clearly describing for each protocol “level” the description of syntax, synchronisation, semantics; and include a description of the Service Access Points.
As reported in [2], [11], and [99]:
SpW does not involve routing (OSI layer 3) but only switching (OSI layer 2). In literature the term Wormhole switching is widely used as a synonymous of wormhole routing. However, the development of SpaceWire higher level protocols in general and the SOIS stack in particular involves routing. The use of this term at SpW level therefore may create confusion.
Moreover, the ECSS-E-ST-50-12C Standard mixes for each protocol “level” the description of syntax, synchronisation, semantics; and it does not describe the Service Access Points. The advantage is that it facilitates the first reading/understanding of the major features of SpaceWire but it also increases the risk of ambiguities when it comes to detailed understanding and implementation
Keep the overall layering as it is but remove any kind of (minor) mixing/overlap between layers in the current standard and clearly define Service Access Points.
“SpW concepts clarification”: redefining,
nodes, units, logical network,
etc.
ECSS-ST-50-12C Rev.1 status | David Jameux | ESTEC | 11/04/2013 | TEC-ED | Slide 4
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Scope
4. Number
5. Location of deficiency
clause page
(e.g. 3.1 14)
6. Changes 7. Justification 8. Disposition
8 7 & 8 52 to 86
Introduce Interrupt distribution codes or more general low-latency signalling codes
As reported in [86], [48], [51], [52], [53], [54], [55], [46], [47], and [49]:
A possible use of one reserved state of the two “control bits” of the SpW standard to allow low-latency distribution of interrupts across SpW networks was presented to the SpW Working group several times. The technical solution was discussed thoroughly and improved.
Some optimisation of this technique allowing low-latency distribution of any kind of signalling code, included but not limited to interrupts and time codes, was recently presented to the SpW Working group.
Once validated by ESA through breadboarding, the feature will be ready for introduction into the new release of the standard.
Include the Distributed Interrupts or more general low latency signalling codes as a new feature in the revised standard. For this, one or more of the three reserved states of the two control bits shall be used.
“Distributed Interrupts”:
improving SUAI proposal (timing
issues ?)
ECSS-ST-50-12C Rev.1 status | David Jameux | ESTEC | 11/04/2013 | TEC-ED | Slide 5
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Scope
“Simplex and Half-Duplex” stream:
studying the relevance and
technical solutions for simplex and for half-duplex SpW
4. Number
5. Location of deficiency
clause page
(e.g. 3.1 14)
6. Changes 7. Justification 8. Disposition
29 8 57 Introduce simplex and/or half-duplex mode(s).
As reported in [61] and [62]:
For many high speed payload data applications only a simplex connection from the instrument to the memory is required. In these cases the back channel provided by SpaceWire is often seen as unnecessary complexity and cable mass. It has been proposed to modify the SpaceWire codec and the state machine to support simplex operation. Also the possibility of a half-duplex SpaceWire implementation has been suggested.
Not to introduce simplex and half-duplex in the update of the SpaceWire standard unless more detailed explanations on the technical solution and on the impact on the current SpaceWire standard are provided very soon.
ECSS-ST-50-12C Rev.1 status | David Jameux | ESTEC | 11/04/2013 | TEC-ED | Slide 6
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ECSS Working Group
1. ECSS New Work Item approved a. Financial resources approved for WG members (industry) b. Manpower approved for ESA coordination
2. Working Group membership approved
1. Work plan
a. Kick-off meeting 22 May 2012 b. 3 other meetings (every 4 months) c. ECSS draft standard for public review
PersonName Position Company Name Nominated byBouabdallah, Ahmed WG Member TELECOM Bretagne EurospaceCook, Barry WG Member 4Links EurospaceDellandrea, Brice WG Member Thales Alenia Space EurospaceHult, Torbjorn WG Member RUAG EurospaceIsomaki, Makro WG Member Aeroflex Gaisler EurospaceJameux, David WG Convenor ESA ESAJoerg, Stefan WG Member DLR DLRNickl, Mathias WG Member DLR DLRNotebaert, Olivier WG Member Astrium Satellites EurospaceParkes, Steve WG Member University of Dundee ESARastetter, Paul WG Member Astrium Satellites EurospaceVigeant, Fabien WG Member CNES CNES
ECSS-ST-50-12C Rev.1 status | David Jameux | ESTEC | 11/04/2013 | TEC-ED | Slide 7
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Background – Open technical issues
1. Tackled through the “SpW Evolutions” TRP activity a. Assessment of simplex and half-duplex SpaceWire – discarded b. Thorough analysis and testing of Distributed Interrupts as
specified by SUAI – refinements c. Clarification of terminology (clear enough to support network
discovery and configuration) 2. Supported by the “Network Discovery Protocols” TRP activity
a. Clarified the concepts of end-point, higher layer and node (including issue of time-code register)
b. Clarified the concept of configuration space for a switch c. Harmonised concepts of configuration space for a switch and
for a node d. Allowed representing any SpW network as a graph
ECSS-ST-50-12C Rev.1 status | David Jameux | ESTEC | 11/04/2013 | TEC-ED | Slide 8
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(from SpW WG mtg#19)
ECSS-ST-50-12C Rev.1 status | David Jameux | ESTEC | 11/04/2013 | TEC-ED | Slide 9
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ECSS SpW Rev WG mtg#3, March 2013
ECSS-ST-50-12C Rev.1 status | David Jameux | ESTEC | 11/04/2013 | TEC-ED | Slide 10
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ECSS SpW Rev WG mtg#3, March 2013
ECSS-ST-50-12C Rev.1 status | David Jameux | ESTEC | 11/04/2013 | TEC-ED | Slide 11
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ECSS SpW Rev WG mtg#3, March 2013
ECSS-ST-50-12C Rev.1 status | David Jameux | ESTEC | 11/04/2013 | TEC-ED | Slide 12
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ECSS SpW Rev WG mtg#3, March 2013
ECSS-ST-50-12C Rev.1 status | David Jameux | ESTEC | 11/04/2013 | TEC-ED | Slide 13
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ECSS SpW Rev WG mtg#3, March 2013
ECSS-ST-50-12C Rev.1 status | David Jameux | ESTEC | 11/04/2013 | TEC-ED | Slide 14
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ECSS SpW Rev WG mtg#3, March 2013
ECSS-ST-50-12C Rev.1 status | David Jameux | ESTEC | 11/04/2013 | TEC-ED | Slide 15
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ECSS SpW Rev WG mtg#3, March 2013
ECSS-ST-50-12C Rev.1 status | David Jameux | ESTEC | 11/04/2013 | TEC-ED | Slide 16
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ECSS SpW Rev WG mtg#3 - Outcome
Terminology: set of terms agreed with their
relationship • Table of SpW Link Level objects • UML diagram of ECSS-E-ST-50-
12C(Rev1) terms
Layering: reduced set of “levels” agreed with their
interfaces • Clear Service Access Point
definitions (implementation is optional)
• List of objects exchanged between levels
Clear definition of services (lists of SAPs) provided by SpaceWire
• Regardless of the internal layering / link technology • Time-codes now clearly exposed at higher level;
Behaviour of all signalling codes (Time-codes, distributed interrupts and acknowledgements) harmonised (not only at SpW Link Level)
• LA check issue and node configuration space issue solved
• Management parameters identified
ECSS-ST-50-12C Rev.1 status | David Jameux | ESTEC | 11/04/2013 | TEC-ED | Slide 17
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Clarified layering
Physical Level
Signal Level
Exchange Level
Character Level
Packet Level
Network Level
Physical Level
Signal Level
Link Level
Network Level
ECSS-ST-50-12C Rev.1 status | David Jameux | ESTEC | 11/04/2013 | TEC-ED | Slide 18
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Clear Service Access Point definitions (implementation is optional) 1/7
SpW Phy Level
SpW Signal Level
SpW Link Level
SpW Network Level
Data Char (8b) or EOP or EEP
Time-code (6b)
Distr. Int. (5b)
Distr. Int. Ack. (5b)
bit
Data Char (8b) or EOP or EEP
Time-code (6b)
Distr. Int. (5b)
Distr. Int. Ack. (5b)
Data Char symbol (10b)
Time-code symbol (14b)
Distr. Int. symbol (14b)
Distr. Int. Ack. Symbol (14b)
EOP/EEP symbol (4b)
SpW PhyLevel SpW Phy Level SpW Phy Level
Nx
ECSS-ST-50-12C Rev.1 status | David Jameux | ESTEC | 11/04/2013 | TEC-ED | Slide 19
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Clear Service Access Point definitions (implementation is optional) 2/7
SpW Phy Level
SpW Signal Level
SpW Link Level
SpW Network Level
Data Char (8b) or EOP or EEP
Time-code (6b)
Distr. Int. (5b)
Distr. Int. Ack. (5b)
bit
Data Char (8b) or EOP or EEP
Time-code (6b)
Distr. Int. (5b)
Distr. Int. Ack. (5b)
Data Char symbol (10b)
Time-code symbol (14b)
Distr. Int. symbol (14b)
Distr. Int. Ack. Symbol (14b)
EOP/EEP symbol (4b)
Phy Level 2 Phy Level 3
ECSS-ST-50-12C Rev.1 status | David Jameux | ESTEC | 11/04/2013 | TEC-ED | Slide 20
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Clear Service Access Point definitions (implementation is optional) 3/7
SpW Phy Level
SpW Signal Level
SpW Link Level
SpW Network Level
Data Char (8b) or EOP or EEP
Time-code (6b)
Distr. Int. (5b)
Distr. Int. Ack. (5b)
bit
Data Char (8b) or EOP or EEP
Time-code (6b)
Distr. Int. (5b)
Distr. Int. Ack. (5b)
Phy Level 2 Phy Level 3
Signal Level 2
bit
Signal Level 3
bit
ECSS-ST-50-12C Rev.1 status | David Jameux | ESTEC | 11/04/2013 | TEC-ED | Slide 21
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Clear Service Access Point definitions (implementation is optional) 4/7
SpW Phy Level
SpW Signal Level
SpW Link Level
SpW Network Level
Data Char (8b) or EOP or EEP
Time-code (6b)
Distr. Int. (5b)
Distr. Int. Ack. (5b)
bit
Data Char (8b) or EOP or EEP
Time-code (6b)
Distr. Int. (5b)
Distr. Int. Ack. (5b)
Phy Level 2 Phy Level 3
Signal Level 2
bit
Signal Level 3
bit
Link Level 2 Link Level 3
ECSS-ST-50-12C Rev.1 status | David Jameux | ESTEC | 11/04/2013 | TEC-ED | Slide 22
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Clear Service Access Point definitions (implementation is optional) 5/7
SpW Signal Level + SpW Physical
Level
SpW Link Level
SpW Network Level
Data Char (8b) or EOP or EEP
Time-code (6b)
Distr. Int. (5b)
Distr. Int. Ack. (5b)
bit
Data Char (8b) or EOP or EEP
Time-code (6b)
Distr. Int. (5b)
Distr. Int. Ack. (5b)
Phy Level 2
Signal Level 2
bit Link Level + Signal Level +
Physical Level 3
ECSS-ST-50-12C Rev.1 status | David Jameux | ESTEC | 11/04/2013 | TEC-ED | Slide 23
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Clear Service Access Point definitions (implementation is optional) 6/7
SpW Network to SpW Physical
Levels
SpW Link Level
SpW Network Level
Data Char (8b) or EOP or EEP
Time-code (6b)
Distr. Int. (5b)
Distr. Int. Ack. (5b)
Data Char (8b) or EOP or EEP
Time-code (6b)
Distr. Int. (5b)
Distr. Int. Ack. (5b)
Phy Level 2
Signal Level 2
bit Link Level + Signal Level +
Physical Level 3
ECSS-ST-50-12C Rev.1 status | David Jameux | ESTEC | 11/04/2013 | TEC-ED | Slide 24
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Clear Service Access Point definitions (implementation is optional) 7/7
ECSS-ST-50-12C Rev.1 status | David Jameux | ESTEC | 11/04/2013 | TEC-ED | Slide 25
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Terminology – router/switch (1/3)
1. Router vs router 2. Switch
5 7 1 EEP cargo
51 EEP cargo 51 = 5-7-1
routing (building a
route)
ECSS-ST-50-12C Rev.1 status | David Jameux | ESTEC | 11/04/2013 | TEC-ED | Slide 26
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Terminology – router/switch (2/3)
1. Router vs router 2. Switch
5
7 1 EEP cargo
3
0
6
7
switching
ECSS-ST-50-12C Rev.1 status | David Jameux | ESTEC | 11/04/2013 | TEC-ED | Slide 27
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Terminology – router/switch (3/3)
1. Router vs router 2. Switch
5
7
1 EEP cargo
3
5
6
0
switching
ECSS-ST-50-12C Rev.1 status | David Jameux | ESTEC | 11/04/2013 | TEC-ED | Slide 28
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Terminology - nodes
1. Is a node a S/W interface or this interface plus the host? 2. Node = end-point + “higher layer”
5 7 1 EEP cargo
51 EEP cargo
higher layer
switch node
5
7 3
5
6
0
end-point
ECSS-ST-50-12C Rev.1 status | David Jameux | ESTEC | 11/04/2013 | TEC-ED | Slide 29
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Terminology – end-points, nodes, units (1/2)
node
1 0 3 4
end-point
2
1 3 4 2
1 0 3 4 2
1 0 3 4 2
switch
higher layer
unit
1553
ECSS-ST-50-12C Rev.1 status | David Jameux | ESTEC | 11/04/2013 | TEC-ED | Slide 30
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Terminology – end-points, nodes, units (2/2)
1 0 3 4 2
1 3 4 2
1 0 3 4 2
1 0 3 4 2
GRAPH
ECSS-ST-50-12C Rev.1 status | David Jameux | ESTEC | 11/04/2013 | TEC-ED | Slide 31
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Terminology - Table of SpW Link Level objects
data signal <none>
data character data characters(0..255)
ctrl characterend-of-packet
markers(EOP & EEP)
FCT & ESC
signalling codes(time-codes, dictr. Int. codes, distr. Int. ack.
Codes, reseved codes)
NULL &invalid codes
N-Char S-Char L-Charflow-controlled
functionality (for the higher layer)
format(othograph
+ syntax)
character
code(ESC + character)
NOT flow-controlledflow-control
SpaceWire Definitions
ECSS Working Group
1
SpaceWire Definitions A node is …
2
3
4
Network
5
Node
Node ID Acceptable LAs
Network
Routing Switch Link
1..M 1..M 0..M
End Point
1..M
1..M
Switch Matrix
1
Routing Table Configured by
Port
Port Number Disable
1 Connects
1
2 Config. Node
Management
0..1
Port
6
Port
Port Number Disable
Input Output
1 1
Link Interface
Enable/Disable
FIFO
…
Node
7
Node
Node ID Acceptable LAs
Configuration
Management
Destination Source End Point
Port
Port Number Disable
1..M
1
Input Output Link Interface
Enable/Disable
FIFO
1 1 …
Unit
8
Unit
Unit ID
Processing Mass Memory
… 0..M 0..M
Node
Node ID Acceptable LAs
Routing Switch
Time-Code
9
Routing Switch
Port
Port Number Disable
Switch Matrix Config. Node
Management
1..M 1 0..1
Signalling Code
Time-Code
Time Count Signal ID = 00
Holds last received End Point
Local BC Reg
Last time-code
1
Port
Port Number Disable
Holds last received
Node
Node ID Acceptable LAs
1..M
Local BC Reg
Last time-code
1
A Node is … A Node is a source or destination of
SpaceWire packets that comprises one or more End Points, has a unique Node ID and a list of Acceptable Logical Addresses that are used to determine which received packets it will accept
A Source Node is a Node that is able to source SpaceWire packets
A Destination Node is a Node that is able to receive SpaceWire packets
A Configuration Node is a Node within a router that is used to access its management information and configure its routing table
10
11
ECSS-ST-50-12C Rev.1 status | David Jameux | ESTEC | 11/04/2013 | TEC-ED | Slide 32
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UML diagram of ECSS-E-ST-50-12C(Rev1) terms (1/4)
Protocol objects
Implemented objects
SpW Network Level
SpW Link Level
ECSS-ST-50-12C Rev.1 status | David Jameux | ESTEC | 11/04/2013 | TEC-ED | Slide 33
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UML diagram of ECSS-E-ST-50-12C(Rev1) terms (2/4)
ECSS-ST-50-12C Rev.1 status | David Jameux | ESTEC | 11/04/2013 | TEC-ED | Slide 34
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UML diagram of ECSS-E-ST-50-12C(Rev1) terms (3/4)
ECSS-ST-50-12C Rev.1 status | David Jameux | ESTEC | 11/04/2013 | TEC-ED | Slide 35
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UML diagram of ECSS-E-ST-50-12C(Rev1) terms (4/4)
ECSS-ST-50-12C Rev.1 status | David Jameux | ESTEC | 11/04/2013 | TEC-ED | Slide 36
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Network Level – Header filtering/deletion in end-points (1/2)
SpW Link Level
SpW Network Level
Data Char (8b) or EOP or EEP
Time-code (6b)
Distr. Int. (5b)
Distr. Int. Ack. (5b)
Data Char (8b) or EOP or EEP
Time-code (6b)
Distr. Int. (5b)
Distr. Int. Ack. (5b)
• Encoding/decoding of data character and signalling codes • Finite State Machine • Serialisation/Deserialisation of characters
• Header filtering on 0 (optional) • Interleaving of data characters/time codes/distributed interrupts (ack) • Packet spilling
ECSS-ST-50-12C Rev.1 status | David Jameux | ESTEC | 11/04/2013 | TEC-ED | Slide 37
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higher layer
Network Level – Header filtering/deletion in end-points (2/2)
SpW Network Level
• Header filtering on 0 (optional) • Interleaving of data characters/time codes/distributed interrupts (ack) • Packet spilling
51 EEP cargo 0 EEP cargo
51 EEP cargo 0 EEP cargo
51 EEP cargo 0 EEP cargo
51 EEP cargo 0 EEP cargo
51 EEP cargo
51 EEP cargo 0 EEP cargo
EEP cargo 63 4
“raw” SpaceWire RMAP
network discovery
ECSS-ST-50-12C Rev.1 status | David Jameux | ESTEC | 11/04/2013 | TEC-ED | Slide 38
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Conclusion (1/2)
1. Layering a. Agreed b. Clear Service Access Points to each level (implementation is
optional) c. Allows substituting levels with other technilogy
2. Nodes vs SpW interface a. Concept of end-point introduced b. Clear definitions of end-points, nodes, units c. “SpW interface” for SpW Link Level, “”SpW port” for SpW
(network level) 3. Clarified “header byte check in nodes”
a. Allows “raw” SpW, packet filtering on LA, network discovery
ECSS-ST-50-12C Rev.1 status | David Jameux | ESTEC | 11/04/2013 | TEC-ED | Slide 39
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Conclusion (2/2)
1. Layering in place 2. Network Level and Link level revised 3. Next step: SpW Signal Level and SpW Physical Level
a. Change Requests b. Inputs by WG c. Support activity “Low Mass SpW cable”
4. ECSS mtg#3 in October 5. Goal: start of public review Q2 2014