Space engineering - Time triggered Ethernet

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 for the 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

Raumfahrttechnik - Zeitgesteuertes Ethernet

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 déclenché par le temps

L'utilisation de protocoles de communication standard pour les liaisons de communication des engins spatiaux peut fournir une compatibilité de l'interface entre les périphériques et les composants de communication. De cette manière, il est possible d'améliorer le processus de conception et de développement, ainsi que les activités d'intégration et d'essai à tous les niveaux, et d'offrir un potentiel de réutilisabilité au travers de plusieurs projets.
La présente norme d'ingénierie spatiale vise à définir les services d'interface et à spécifier leurs éléments de protocole réseau correspondants pour un engin spatial utilisant le réseau de données Ethernet à déclenchement temporel (TTEthernet). Elle vise par ailleurs à définir les exigences nécessaires à l'harmonisation des interfaces physiques et à l'utilisation des fonctionnalités des couches [IEEE 802.3] et [SAE AS6802].
La présente norme peut être adaptée aux caractéristiques et contraintes spécifiques d'un projet spatial, conformément à l'ECSS‐S‐ST‐00.
Approche
L'approche du groupe de travail ECSS, dans le cadre de la définition de la présente norme, vise à identifier les couches, services et fonctions du réseau de communication TTEthernet courant afin de garantir l'utilisation de cette technologie pour divers projets spatiaux. La présente norme vise à :
- identifier les architectures de référence (couches, services, fonctions et éléments de protocole) du réseau de communication TTEthernet courant ;
- caractériser les services, fonctions et éléments de protocole pour chaque couche au sein des architectures de référence identifiées, en utilisant des spécifications de projet concrètes ;
- définir des exigences normatives plutôt que des recommandations.
Dans la mesure du possible, les exigences de communication définies sont tirées de l'expérience avec des spécifications d'engins spatiaux existantes.

Vesoljska tehnika - Časovno proženi ethernet

Uporaba standardnih komunikacijskih protokolov za komunikacijske povezave vesoljskih plovil lahko zagotovi združljivost vmesnikov med komunikacijskimi napravami in komponentami. Tako je mogoče izboljšati postopek načrtovanja in razvoja kot tudi vključevanja in preskusnih dejavnosti na vseh ravneh ter zagotovi možnost
vnovične uporabe pri drugih projektih.
Cilj tega standarda vesoljske tehnike je opredeliti vmesniške storitve in določiti njihove ustrezne elemente omrežnega protokola za vesoljska plovila z uporabo časovno proženega podatkovnega omrežja Ethernet. Cilj je tudi opredeliti zahteve za harmonizacijo fizičnih vmesnikov in uporabo funkcij plasti iz standardov [IEEE 802.3] in [SAE AS6802].
Ta standard se lahko prilagodi posameznim lastnostim in omejitvam vesoljskega projekta v skladu s standardom ECSS‐S‐ST‐00.

General Information

Status
Published
Public Enquiry End Date
28-Apr-2021
Publication Date
23-Jan-2022
Technical Committee
Current Stage
6060 - National Implementation/Publication (Adopted Project)
Start Date
29-Dec-2021
Due Date
05-Mar-2022
Completion Date
24-Jan-2022

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SLOVENSKI STANDARD
SIST EN 16603-50-16:2022
01-marec-2022
Vesoljska tehnika - Časovno proženi ethernet
Space engineering - Time triggered Ethernet
Raumfahrttechnik - Zeitgesteuertes Ethernet
Ingénierie spatiale - Ethernet déclenché par le temps
Ta slovenski standard je istoveten z: EN 16603-50-16:2021
ICS:
49.140 Vesoljski sistemi in operacije Space systems and
operations
SIST EN 16603-50-16:2022 en,fr,de

2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

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SIST EN 16603-50-16:2022
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SIST EN 16603-50-16:2022
EUROPEAN STANDARD EN 16603-50-16
NORME EUROPÉENNE
EUROPÄISCHE NORM
December 2021
ICS 49.140
English version
Space engineering - Time triggered Ethernet

Ingénierie spatiale - Ethernet à déclenchement Raumfahrttechnik - Zeitgesteuertes Ethernet

temporel (TTE)
This European Standard was approved by CEN on 5 December 2021.

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. Up-to-date lists and bibliographical

references concerning such national standards may be obtained on application to the CEN-CENELEC Management Centre or to

any CEN and CENELEC member.

This European Standard exists 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.
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. EN 16603-50-16:2021 E
reserved worldwide for CEN national Members and for
CENELEC Members.
---------------------- Page: 3 ----------------------
SIST EN 16603-50-16:2022
EN 16603-50-16:2021 (E)
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................................................................................................... 15

3.4 Nomenclature ......................................................................................................... 17

4 Overview ................................................................................................................ 18

4.1 Reference Model .................................................................................................... 18

4.2 Physical Layer ........................................................................................................ 19

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 ................................................................. 30

4.4.6 Rate-Constrained Traffic Policing .............................................................. 30

4.4.7 Clock Synchronization ............................................................................... 31

4.5 Redundancy Concept ............................................................................................. 34

4.5.1 Introduction ............................................................................................... 34

4.5.2 TT traffic .................................................................................................... 35

4.5.3 RC traffic ................................................................................................... 35

4.6 Failure-modes ......................................................................................................... 36

5 Network Architecture ........................................................................................... 37

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5.1 Overview ................................................................................................................ 37

5.1.1 Introduction ............................................................................................... 37

5.1.2 Single Channel Network Topology ............................................................ 37

5.1.3 Dual Channel Network Topology ............................................................... 38

5.1.4 Triple Channel Network Topology ............................................................. 39

5.1.5 Mixed Network Topology ........................................................................... 40

5.1.6 Multiple Networks Topology ...................................................................... 41

5.1.7 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 .......................................................................................... 48

6.2.4 MAC Transmit ........................................................................................... 49

6.2.5 MAC Receive ............................................................................................ 50

6.2.6 Switch Traffic Policing ............................................................................... 50

6.2.7 Switch Transmit ........................................................................................ 51

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 End-System Level Specification ................................................................ 59

7.2.5 Clock Synchronization ............................................................................... 60

7.3 Configuration Parameters ....................................................................................... 61

7.3.1 Device Level and Clock Synchronization Parameters ............................... 61

7.4 Configuration and Scheduling guideline .................................................................. 67

7.4.1 Overview ................................................................................................... 67

7.4.2 Delays ....................................................................................................... 68

7.4.3 Latencies .................................................................................................. 69

7.4.4 Transparent clock ..................................................................................... 70

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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

7.5.4 Maximum transparent clock ...................................................................... 72

7.5.5 PCF transparent clock jitter ....................................................................... 72

7.5.6 Precision parameter .................................................................................. 73

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 ........................................................ 81

8.4.1 Simple Network Management Protocol (SNMP) Overview ........................ 81

8.4.2 SNMP requirements .................................................................................. 83

8.4.3 Diagnostic and Status-Information requirements ....................................... 84

8.4.4 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 ..................................... 91

10 Tailoring .............................................................................................................. 92

10.1 Scope ..................................................................................................................... 92

10.2 Tailoring options and parameters ............................................................................ 92

10.2.1 Overview ................................................................................................... 92

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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

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: Time-Triggered Ethernet two step clock synchronization algorithm .................. 31

Figure 4-18: Example of an integration PCF Frame exchange ............................................. 34

Figure 4-19: Redundancy Communication............................................................................ 34

Figure 4-20: 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

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SIST EN 16603-50-16:2022
EN 16603-50-16:2021 (E)

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 Ethernet nodes ....... 43

Figure 6-1: OSI Layer Services ............................................................................................ 46

Figure 6-2: Destination MAC Address .................................................................................. 47

Figure 6-3: Source MAC Address ......................................................................................... 47

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 ................................................................ 69

Figure 7-4: Impact of delays on synchronization precision .................................................... 69

Figure 7-5: Impact of delays on synchronization precision .................................................... 71

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 .................................................................................. 83

Tables

Table 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 ....................................................................... 62

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 ............................................................................ 65

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

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SIST EN 16603-50-16:2022
EN 16603-50-16:2021 (E)

Table 7-18: TT Switch Receive Window start and end time .................................................. 74

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

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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SIST EN 16603-50-16:2022
EN 16603-50-16:2021 (E)
European Foreword
This document (EN 16603-50-16:2021) has been prepared by Technical
Committee CEN-CENELEC/TC 5 “Space”, the secretariat of which is held by
DIN.
This standard (EN 16603-50-16:2021) originates from ECSS-E-ST-50-16C.
This European Standard shall be given the status of a national standard, either

by publication of an identical text or by endorsement, at the latest by June 2022,

and conflicting national standards shall be withdrawn at the latest by June 2022.

Attention is drawn to the possibility that some of the elements of this document
may be the subject of patent rights. CEN [and/or CENELEC] shall not be held
responsible for identifying any or all such patent rights.
This document has been prepared under a standardization request given to
CEN by the European Commission and the European Free Trade Association.
This document has been developed to cover specifically space systems and has
therefore precedence over any EN covering the same scope but with a wider
domain of applicability (e.g. : aerospace).
According to the CEN-CENELEC Internal Regulations, the national standards
organizations of the following countries are bound to implement this European
Standard: Austria, Belgium, Bulgaria, Croatia, Cyprus, Czech Republic,
Denmark, Estonia, Finland, Former Yugoslav Republic of Macedonia, France,
Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania,
Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Romania, Serbia,
Slovakia, Slovenia, Spain, Sweden, Switzerland, Turkey and the United
Kingdom.
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SIST EN 16603-50-16:2022
EN 16603-50-16:2021 (E)
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 for the 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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SIST EN 16603-50-16:2022
EN 16603-50-16:2021 (E)
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 latest
edition 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 7, Aircraft Data Network Part 2: Avionic Full-Duplex
23 September 2009 Switched Ethernet Network
IEEE 802.3, Ethernet Standard
28 December 2012
SAE AS6802, Time-Triggered Ethernet
November 2011
RFC 768, User Datagram Protocol (UDP)
28 August 1980
RFC 791, September Internet Protocol (IP)
1981
RFC 792, September Internet Control Message Protocol (ICMP)
1981
RFC 1157, May 1990 A simple network management protocol (for
SNMPv1)
RFC 1350, July 1992 The TFTP Protocol (Revision 2)
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SIST EN 16603-50-16:2022
EN 16603-50-16:2021 (E)
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
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 uses them in a timing a
...

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
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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 for
CENELEC Members.
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oSIST prEN 16603-50-16:2021
prEN 16603-50-16:2021 (E)
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 ............... 82

8.4.2 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 Ethernet

nodes ........................................................................................................ 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

Tables

Table 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 for
the 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 latest
edition 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 marker
NOTE 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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