prEN 16603-50-16
(Main)Space engineering - Time triggered Ethernet
Space engineering - Time triggered Ethernet
Raumfahrttechnik - Zeitgesteuertes Ethernet (TTE)
The transmission of onboard data is ever increasing. Particularly in the manned space arena, requirements already exist for concurrent transmission of many different types of data with different data rates, time criticality and priority. Currently this is handled by multiple busses and LANs but could be supported by a single TTE based infrastructure.
A form of TTE is already in use by the Multi-Purpose Crew Vehicle (MPCV), a NASA led manned vehicle which includes a separate service model under development by ESA. In addition TTE has been selected by for use by the Ariane 6 program. Both of these developments require the transmission of mixed data types at relatively high speeds.
The present MPCV implementation is based on a proprietary approach. It is effectively a closed development by a non-European single vendor with a design that includes ITAR components. Indeed MPCV TTE implementation cannot be applied to European Launchers and in general to future European programs which could need an open standard able to be implemented by multiple suppliers. For this reason ESA has been approached by industry requesting that an ECSS standard is being produced.
The existing SAE standard may form the basis for such a standard but needs to be extended for space in the areas of physical medium, redundancy, testing and verification. Some aspects of time distribution must be more precisely documented and any patent issues resolved.
This standard would foster a faster adoption of the technology and simplify the customer/ supplier contractual relationship especially with an IP core based synchronisation client available to the Space Industry via ESA IP core portfolio.
Whether this standard would complement the existing SAE6802 by filling existing gaps , especially on the physical layer and the interoperability, or would include all necessary information from the SAE 6802 issue 1 to achieve a stand-alone document, is part of a trade-off assessment the WG will have to undertake.
Ingénierie spatiale - Ethernet à déclenchement temporel (TTE)
Vesoljska tehnika - Časovno proženi ethernet
General Information
Standards Content (sample)
SLOVENSKI STANDARD
oSIST prEN 16603-50-16:2021
01-april-2021
Vesoljska tehnika - Časovno proženi ethernet
Space engineering - Time triggered Ethernet
Raumfahrttechnik - Zeitgesteuertes Ethernet (TTE)
Ingénierie spatiale - Ethernet à déclenchement temporel (TTE)
Ta slovenski standard je istoveten z: prEN 16603-50-16
ICS:
49.140 Vesoljski sistemi in operacije Space systems and
operations
oSIST prEN 16603-50-16:2021 en,fr,de
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.
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oSIST prEN 16603-50-16:2021
EUROPEAN STANDARD
DRAFT
prEN 16603-50-16
NORME EUROPÉENNE
EUROPÄISCHE NORM
February 2021
ICS 49.140
English version
Space engineering - Time triggered Ethernet
Ingénierie spatiale - Ethernet à déclenchement Raumfahrttechnik - Zeitgesteuertes Ethernet (TTE)
temporel (TTE)This draft European Standard is submitted to CEN members for enquiry. It has been drawn up by the Technical Committee
CEN/CLC/JTC 5.If this draft becomes a European Standard, CEN and CENELEC members are bound to comply with the CEN/CENELEC Internal
Regulations which stipulate the conditions for giving this European Standard the status of a national standard without any
alteration.This draft European Standard was established by CEN and CENELEC in three official versions (English, French, German). A
version in any other language made by translation under the responsibility of a CEN and CENELEC member into its own
language and notified to the CEN-CENELEC Management Centre has the same status as the official versions.
CEN and CENELEC members are the national standards bodies and national electrotechnical committees of Austria, Belgium,
Bulgaria, Croatia, Cyprus, Czech Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy,
Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Republic of North Macedonia, Romania, Serbia,
Slovakia, Slovenia, Spain, Sweden, Switzerland, Turkey and United Kingdom.Recipients of this draft are invited to submit, with their comments, notification of any relevant patent rights of which they are
aware and to provide supporting documentation.Recipients of this draft are invited to submit, with their comments, notification
of any relevant patent rights of which they are aware and to provide supporting documentation.
Warning : This document is not a European Standard. It is distributed for review and comments. It is subject to change without
notice and shall not be referred to as a European Standard.CEN-CENELEC Management Centre:
Rue de la Science 23, B-1040 Brussels
© 2021 CEN/CENELEC All rights of exploitation in any form and by any means Ref. No. prEN 16603-50-16:2021 E
reserved worldwide for CEN national Members and forCENELEC Members.
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Table of contents
European Foreword .......................................................................................... 8
1 Scope .............................................................................................................. 9
2 Normative references .................................................................................. 10
3 Terms, definitions and abbreviated terms ................................................. 11
3.1 Terms from other standards ........................................................................... 11
3.2 Terms specific to the present standard .......................................................... 11
3.3 Abbreviated terms.......................................................................................... 14
3.4 Nomenclature ................................................................................................ 16
4 Overview ....................................................................................................... 18
4.1 Reference Model ........................................................................................... 18
4.2 Physical Layer ............................................................................................... 18
4.3 Data Link Layer ............................................................................................. 19
4.3.1 Data Link Layer Overview ................................................................ 19
4.3.2 Data Link Layer Functionalities ........................................................ 20
4.3.3 Time-Triggered Ethernet .................................................................. 21
4.4 Network Level ................................................................................................ 23
4.4.1 Network Level Overview................................................................... 23
4.4.2 Message Processing at the Switch ................................................... 24
4.4.3 Time-Triggered Ethernet Network Building Blocks ........................... 28
4.4.4 Virtual Link ....................................................................................... 29
4.4.5 Time-Triggered Traffic Policing ........................................................ 29
4.4.6 Rate-Constraint Traffic Policing ........................................................ 30
4.4.7 Clock Synchronization ...................................................................... 31
4.5 Redundancy Concept .................................................................................... 34
4.5.1 TT-traffic .......................................................................................... 35
4.5.2 RC-traffic .......................................................................................... 35
4.6 Failure-modes ................................................................................................ 36
5 Network Architecture .................................................................................. 37
5.1 Overview ....................................................................................................... 37
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5.1.1 Single Channel Network Topology ................................................... 37
5.1.2 Dual Channel Network Topology ...................................................... 38
5.1.3 Triple Channel Network Topology .................................................... 39
5.1.4 Mixed Network Topology .................................................................. 40
5.1.5 Multiple Networks Topology ............................................................. 41
5.1.6 Compatibility with standard Ethernet Network .................................. 42
5.2 Network Topology Requirements ................................................................... 43
5.2.1 Single Network Topology ................................................................. 43
5.2.2 Multiple Networks Topology ............................................................. 45
6 Device Services ........................................................................................... 46
6.1 Overview ....................................................................................................... 46
6.2 Media Access Control (MAC) Sublayer .......................................................... 47
6.2.1 MAC sublayer functions ................................................................... 47
6.2.2 MAC Addressing .............................................................................. 47
6.2.3 Traffic Classes ................................................................................. 49
6.2.4 MAC Transmit .................................................................................. 49
6.2.5 MAC Receive ................................................................................... 50
6.2.6 Switch Traffic Policing ...................................................................... 50
6.2.7 Switch Transmit ............................................................................... 52
6.2.8 Switch Frame Routing ...................................................................... 52
7 Interoperability Specification ..................................................................... 53
7.1 Overview ....................................................................................................... 53
7.2 Device Specification ...................................................................................... 54
7.2.1 Device Parameters Description ........................................................ 54
7.2.2 General Requirements ..................................................................... 55
7.2.3 Switch Level Specification ................................................................ 55
7.2.4 Switch Forwarding............................................................................ 55
7.2.5 End System Level Specification ....................................................... 58
7.2.6 Clock Synchronization ...................................................................... 60
7.3 Configuration Parameters .............................................................................. 60
7.3.1 Device Level and Clock Synchronization Parameters ...................... 60
7.4 Configuration and Scheduling guideline ......................................................... 67
7.4.1 Overview .......................................................................................... 67
7.5 Scheduling requirements ............................................................................... 70
7.5.1 Delays to be identified ...................................................................... 70
7.5.2 Delays compensation ....................................................................... 70
7.5.3 PCF latency ..................................................................................... 71
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7.5.4 Maximum transparent clock ............................................................. 71
7.5.5 PCF transparent clock jitter .............................................................. 72
7.5.6 Precision parameter ......................................................................... 72
7.5.7 Time-Triggered minimum gap .......................................................... 73
7.5.8 Time-Triggered Switch receive window ............................................ 73
7.5.9 Time-Triggered Switch minimum transmission ................................. 75
7.5.10 Time-Triggered end system reception .............................................. 75
8 Network Setup and Services ...................................................................... 76
8.1 Overview ....................................................................................................... 76
8.2 General Requirements ................................................................................... 77
8.2.1 Overview .......................................................................................... 77
8.2.2 Internet Protocol (IP) ........................................................................ 77
8.2.3 UDP ................................................................................................. 78
8.2.4 ICMP ................................................................................................ 79
8.3 Dataloading via TFTP .................................................................................... 80
8.3.1 Trivial File Transfer Protocol (TFTP) Overview ................................. 80
8.3.2 Dataloading requirements ................................................................ 81
8.4 Diagnostics and Status-Information via SNMP ............................................... 82
8.4.1 Simple Network Management Protocol (SNMP) Overview ............... 828.4.2 Diagnostic and Status-Information requirements .............................. 84
8.4.3 Monitoring Mode .............................................................................. 88
8.5 Error management in End System and Switch ............................................... 88
9 Test and verification .................................................................................... 90
9.1 Test Specification .......................................................................................... 90
9.2 Test references .............................................................................................. 90
9.2.1 Overview .......................................................................................... 90
9.2.2 Requirements for implementation at system level ............................ 90
10 Tailoring ..................................................................................................... 92
10.1 Scope ............................................................................................................ 92
10.2 Tailoring options and parameters ................................................................... 92
10.2.1 Overview .......................................................................................... 92
10.2.2 Step 1: Function and service selection ............................................. 92
10.2.3 Step 2: Services configuration .......................................................... 92
10.3 IEEE 802.3 Tailoring ...................................................................................... 93
10.4 SAE AS6802 Tailoring ................................................................................... 97
Bibliography .................................................................................................. 102
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Figures
Figure 3-1: Structure of a Packet ................................................................................. 13
Figure 4-1: OSI Reference Model ................................................................................ 18
Figure 4-2: Physical Layer Model ................................................................................ 19
Figure 4-3: Data Link Layer ......................................................................................... 20
Figure 4-4: Time-Triggered Ethernet Services ............................................................. 21
Figure 4-5: Traffic Partitioning ..................................................................................... 23
Figure 4-6: Network Communication Channel ............................................................. 23
Figure 4-7: A TTE example network ............................................................................ 24
Figure 4-8: Full Duplex Links ....................................................................................... 24
Figure 4-9: Message Processing at the Switch ............................................................ 25
Figure 4-10: Preemption .............................................................................................. 26
Figure 4-11: Shuffling .................................................................................................. 27
Figure 4-12: Media Reservation .................................................................................. 27
Figure 4-13: Network Building Blocks .......................................................................... 28
Figure 4-14: Network Building Blocks Examples.......................................................... 28
Figure 4-15: Virtual Link .............................................................................................. 29
Figure 4-16: Bandwidth Reservation ............................................................................ 30
Figure 4-17: Token Bucket Principle ............................................................................ 30
Figure 4-18: Time-Triggered Ethernet two step clock synchronization algorithm ......... 31
Figure 4-19: Example of an integration PCF Frame exchange .................................... 34
Figure 4-20: Redundancy Communication................................................................... 34
Figure 4-21: Redundancy Management at the Receiver .............................................. 35
Figure 5-1: Single Channel Network Topology ............................................................ 37
Figure 5-2: Single Channel Network Topology – without cascaded Switches .............. 38
Figure 5-3: Single Channel Network Topology – with cascaded Switches ................... 38
Figure 5-4: Dual Channel Network Topology ............................................................... 38
Figure 5-5: Dual Channel Network Redundancy without cascaded Switches .............. 39
Figure 5-6: Dual Channel Network Redundancy with cascaded Switches ................... 39
Figure 5-7: Triple Channel Redundant Network Topology ........................................... 39
Figure 5-8: Triple Channel Network Redundancy without cascaded Switches ............. 40
Figure 5-9: Triple Channel Network Redundancy with cascaded Switches .................. 40
Figure 5-10: Mixed Architecture ................................................................................... 40
Figure 5-11: Multiple Networks Topology .................................................................... 41
Figure 5-12: Synchronization priority assignment recommendation ............................. 42
Figure 5-13: Time-Triggered Ethernet topology composed of standard Ethernetnodes ........................................................................................................ 43
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Figure 6-1: OSI Layer Services ................................................................................... 46
Figure 6-2: Destination MAC Address ......................................................................... 47
Figure 6-3: Source MAC Address ................................................................................ 48
Figure 7-1: Configuration Interface Tool – IP ............................................................... 53
Figure 7-2: Example of delays at system level ............................................................. 68
Figure 7-3: Example of delays related to a device ....................................................... 68
Figure 7-4: Impact of delays on synchronization precision ........................................... 69
Figure 7-5: Impact of delays on synchronization precision ........................................... 70
Figure 7-6: Impact of delays on synchronization precision ........................................... 71
Figure 8-1: Network Diagnostic and Monitoring Service Layers ................................... 77
Figure 8-2: FTP Message Types ................................................................................. 81
Figure 8-3: Simple Network Management Protocol (SNMP) ........................................ 82
Figure 8-4: Global SNMP architecture ......................................................................... 84
TablesTable 6-1: Interface ID ................................................................................................. 48
Table 7-1: General Interoperability Parameter Table ................................................... 54
Table 7-2: Switch Interoperability Parameter Table ..................................................... 54
Table 7-3: End System Interoperability Parameter Table ............................................. 55
Table 7-4: End System Schedule Parameters ............................................................. 61
Table 7-5: End-System Output VL Parameters ............................................................ 61
Table 7-6: End-System Input VL Parameters .............................................................. 61
Table 7-7: End-System Best effort Filtering Parameters .............................................. 62
Table 7-8: End-System Clock Synchronization Parameters ......................................... 62
Table 7-9: End-System General Parameters ............................................................... 64
Table 7-10: Switch Scheduling Parameters ................................................................. 64
Table 7-11: Switch Output VL Parameters ................................................................... 64
Table 7-12: Switch Input VL Parameters ..................................................................... 65
Table 7-13: Switch Best Effort Filtering Parameters .................................................... 65
Table 7-14: Switch Clock Synchronization Parameters................................................ 65
Table 7-15: Switch General Parameter ........................................................................ 67
Table 7-16: Max Transparent Clock parameter table ................................................... 72
Table 7-17: Precision parameter Table ........................................................................ 73
Table 7-18: TT Switch Receive Window start and end time ......................................... 73
Table 7-19: Time-Triggered Switch receive window Table ........................................... 74
Table 10-1: Requirements selection ............................................................................ 93
Table 10-2: Tailoring to [IEEE 802.3] - Part 3 .............................................................. 93
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Table 10-3: Tailoring to [SAE AS6802] ........................................................................ 97
Table A-1 : Clock Synchronization ............................................................................... 98
Table A-2 : Time-Triggered Communication ................................................................ 99
Table A-3 : Dependability ............................................................................................ 99
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European Foreword
This document (prEN 16603-50-16:2021) has been prepared by Technical
Committee CEN/CLC/TC 5 “Space”, the secretariat of which is held by DIN
(Germany).
This document (prEN 16603-50-16:2021) originates from ECSS-E-ST-50-16C
DIR1.
This document is currently submitted to the Enquiry.
This document has been developed to cover specifically space systems and will
therefore have precedence over any EN covering the same scope but with a wider
do-main of applicability (e.g. : aerospace).
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Scope
Using standard communication protocols for spacecraft communication links
can provide interface compatibility between communication devices and
components. Thus, it can improve the design and development process as well
as integration and test activities at all levels and provide the potential of
reusability across projects.
The aim of this space engineering standard is to define the interface services and
to specify their corresponding network protocol elements for spacecraft using the
Time-Triggered Ethernet data network. It also aims at defining requirements forthe harmonisation of the physical interfaces and usage of the [IEEE 802.3] and
[SAE AS6802] layer features.
This standard may be tailored for the specific characteristic and constraints of a
space project in conformance with ECSS‐S‐ST‐00.Approach
The approach of the ECSS working group for defining this standard aims at
identification of layers, services and functions of the typical Time-Triggered
Ethernet communication network to ensure the use of the technology for various
space projects. The standard aims at:
Identifying Reference Architectures (Layers, Services, Functions and
Elements of protocol) of typical Time-Triggered Ethernet communication
network;
Characterizing Services, Functions and Elements of Protocol of each Layer
within identified Reference Architectures, using concrete project
specifications;
Define normative requirements rather than recommendations.
As far as possible, the defined communication requirements are extracted from
the experience on existing spacecraft specifications.
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Normative references
The following normative documents contain provisions which, through
reference in this text, constitute provisions of this ECSS Standard. For dated
references, subsequent amendments to, or revision of any of these publications
do not apply. However, parties to agreements based on this ECSS Standard are
encouraged to investigate the possibility of applying the more recent editions of
the normative documents indicated below. For undated references, the latestedition of the publication referred to applies.
EN reference Reference in text Title
EN 16601-00-01 ECSS-S-ST-00-01 ECSS System - Glossary of terms
ARINC 664 part 2, Aircraft Data Network Part 2: Ethernet
24 October 2018 Physical and Data Link Layer Specification
ARINC 664 part 7, Aircraft Data Network Part 2: Avionic Full-
23 September 2009 Duplex Switched Ethernet Network
IEEE 802.3, Ethernet Standard
28 December 2012
SAE AS6802, Time-triggered Ethernet
November 2011
RFC 768, 28 August 1980 User Datagram Protocol (UDP)
RFC 791, September 1981 Internet Protocol (IP)
RFC 792, September 1981 Internet Control Message Protocol (ICMP)
RFC 1157, May 1990 A simple network management protocol (for
SNMPv1)
RFC 1350, July 1992 The TFTP Protocol (Revision 2)
RFC 2349, May 1998 TFTP Timeout Interval and Transfer Size
Options
RFC 3697, March 2004 IPv6 Flow Label Specification
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Terms, definitions and abbreviated terms
3.1 Terms from other standards
For the purpose of this Standard, the terms and definitions from ECSS-S-ST-00-
01 apply.
3.2 Terms specific to the present standard
3.2.1 acceptance window
timing interval in which the reception of the frame associated with a VL ID is
expected
3.2.2 bandwidth allocation gap (BAG)
minimum delay between two consecutive Rate-Constrained frames belonging to
the same sending interval
[ARINC 664 part 7]
3.2.3 best-effort traffic
standard Ethernet frame which is neither critical traffic nor flow controlled
traffic
NOTE A Best-Effort frame or traffic as specified by the
standard [IEEE 802.3].
3.2.4 broadcast
transmission of an Ethernet frame from one sender to all receivers
3.2.5 cluster
Ethernet network composed of nodes synchronized to each other by the time-
triggered Ethernet protocol
3.2.6 compression master
role of an element of the cluster that collects protocol control frames (PCFs) from
the synchronization masters and compresses uses them in a timing algorithm,compression, before sending them back to the configured synchronization
masters and synchronization clients, to be used for synchronization purpose
3.2.7 critical traffic (CT)
flow of critical traffic frames, where each frame has the most significant 32 bits
set to the critical traffic markerNOTE Critical Traffic Marker is the value of the most
significant 32 bits of the MAC Destination
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Address that identifies a frame as Critical
Traffic.
3.2.8 device
element of an Ethernet network or an element connected to an Ethernet node
NOTE A device can be either a switch or an end system
or a host computer. A device does not
necessarily support RC or TT or BE traffic.
3.2.9 end system
network component which provides the host device an interface to the network
NOTE Each host device uses an End System interface to
guarantee a secure and reliable data interchange
with other host device.
3.2.10 flow controlled traffic
sequence of Ethernet packets from one sender to one or multiple receivers
NOTE A Flow controlled traffic as specified by [RFC
3697].
3.2.11 frame
part of a packet
NOTE 1 The following frame types are used throughout
this document:
Best-Effort frame: Basic Frame
Critical Traffic frame: Rate-Constrained (RC)
frame; Protocol Control Frame (is a RC
frame); Time-Triggered (TT) frame
NOTE 2 Example of a packet is shown in Figure 3-1.
3.2.12 globally administered
unique MAC address assigned to the network interface card by the manufacturer
3.2.13 link
physical connections between nodes in a network providing the means for
transferring frames between them
3.2.14 locally administered
unique MAC address assigned to the network interface card locally
3.2.15 multicast
transmission of an Ethernet frame from one sender to multiple receivers
3.2.16 node
element of an Ethernet network
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NOTE A node can be either a Switch or an End System.
A node does
...
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