ISO 18440:2013

INTERNATIONAL ISO
STANDARD 18440
First edition
2013-06-01
Space data and information transfer
systems — Space Link Extension —
Internet Protocol for Transfer Services
Systèmes de transfert des informations et données spatiales —
Extension de liaisons spatiales — Protocole Internet pour services de
transfert
Reference number
©
ISO 2013
©  ISO 2013
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ii © ISO 2013 – All rights reserved

Foreword
ISO (the International Organization for Standardization) is a worldwide federation of national standards bodies
(ISO member bodies). The work of preparing International Standards is normally carried out through ISO
technical committees. Each member body interested in a subject for which a technical committee has been
established has the right to be represented on that committee. International organizations, governmental and
non-governmental, in liaison with ISO, also take part in the work. ISO collaborates closely with the
International Electrotechnical Commission (IEC) on all matters of electrotechnical standardization.
The procedures used to develop this document and those intended for its further maintenance are described
in the ISO/IEC Directives, Part 1. In particular the different approval criteria needed for the different types of
ISO documents should be noted. This document was drafted in accordance with the editorial rules of the
ISO/IEC Directives, Part 2. www.iso.org/directives
Attention is drawn to the possibility that some of the elements of this document may be the subject of patent
rights. ISO shall not be held responsible for identifying any or all such patent rights. Details of any patent
rights identified during the development of the document will be in the Introduction and/or on the ISO list of
patent declarations received. www.iso.org/patents
Any trade name used in this document is information given for the convenience of users and does not
constitute an endorsement.
ISO 18440 was prepared by the Consultative Committee for Space Data Systems (CCSDS) (as
CCSDS 913.1-B-1, September 2008) and was adopted (without modifications except those stated in Clause 2
of this International Standard) by Technical Committee ISO/TC 20, Aircraft and space vehicles, Subcommittee
SC 13, Space data and information transfer systems.

INTERNATIONAL STANDARD ISO 18440:2013(E)

Space data and information transfer systems — Space Link
Extension — Internet Protocol for Transfer Services
1 Scope
The Space Link Extension (SLE) Reference Model identifies a set of SLE Transfer Services that enable
missions to send forward space link data units to a spacecraft and to receive return space link data units from
a spacecraft. A subset of these services is specified by the SLE Transfer Service Recommended Standards.
The SLE Transfer Service Recommended Standards specify:
a) the operations necessary to provide the transfer service;
b) the parameter data associated with each operation;
c) the behaviors that result from the invocation of each operation; and
d) the relationship between, and the valid sequence of, the operations and resulting behaviors.
However, they deliberately do not specify the methods or technologies required for communications.
The purpose of this International Standard is to define a protocol for transfer of SLE Protocol Data Units
(PDUs) defined in the SLE Transfer Service Recommended Standards using the Internet protocols TCP
(Transmission Control Protocol and IP (Internet Protocol) for data transfer and the Abstract Syntax Notation
One (ASN.1) for data encoding. This protocol is referred to as the Internet SLE Protocol One (ISP1).
This International Standard defines a protocol for transfer of SLE PDUs between an SLE user and an SLE
provider system in terms of:
a) the procedures used to establish and release associations;
b) the messages exchanged on an established association;
c) the procedures used to monitor the status of data communication connections; and
d) the methods used to ensure that data are converted between different formats and representations on
different platforms.
It does not specify:
a) individual designs, implementations, or products;
b) the configuration of the data communications infrastructure, including configuration of the TCP and IP
protocols;
c) the means by which addresses (IP addresses and TCP port numbers) are agreed, assigned, and
communicated.
This International Standard responds to the requirements imposed by the International Standards for SLE
transfer services that were available when this International Standard was released. The protocol specified in
this International Standard conforms to the requirements on data communication services set forth in those
International Standards.
The scope and field of application are furthermore detailed in subclause 1.3 of the enclosed CCSDS
publication.
2 Requirements
Requirements are the technical recommendations made in the following publication (reproduced on the
following pages), which is adopted as an International Standard:
CCSDS 913.1-B-1, September 2008, Space·Link·Extension·--·Internet·Protocol·for·Transfer·Services.
For the purposes of international standardization, the modifications outlined below shall apply to the specific
clauses and paragraphs of publication CCSDS 913.1-B-1.
Pages i to v
This part is information which is relevant to the CCSDS publication only.
Page 1-7 and 1-8
Add the following information to the reference indicated:
[1] Document CCSDS 910.4-B-2, October 2005, is equivalent to ISO 15396:2007.
[2] Document CCSDS 911.1-B-2, December 2004, is equivalent to ISO 22669:2007.
[3] Document CCSDS 911.2-B-1, December 2004, is equivalent to ISO 22670:2006.
[4] Document CCSDS 911.5-B-1, December 2004, is equivalent to ISO 26143:2007.
[5] Document CCSDS 912.1-B-2, December 2004, is equivalent to ISO 22671:2011.
[6] Document CCSDS 912.3-B-1, December 2004, is equivalent to ISO 22672:2011.
[13] Document CCSDS 301.0-B-3, January 2002, is equivalent to ISO 11104:2011.
3 Revision of publication CCSDS 913.1-B-1
It has been agreed with the Consultative Committee for Space Data Systems that Subcommittee
ISO/TC 20/SC 13 will be consulted in the event of any revision or amendment of publication CCSDS 913.1-
B-1. To this end, NASA will act as a liaison body between CCSDS and ISO.

2 © ISO 2013 – All rights reserved

Recommendation for Space Data System Standards
SPACE LINK EXTENSION—
INTERNET PROTOCOL FOR
TRANSFER SERVICES
RECOMMENDED STANDARD
CCSDS 913.1-B-1
BLUE BOOK
September 2008
SPACE LINK EXTENSION—INTERNET PROTOCOL FOR TRANSFER SERVICES
AUTHORITY
Issue: Recommended Standard, Issue 1
Date: September 2008
Location: Washington, DC, USA
This document has been approved for publication by the Management Council of the
Consultative Committee for Space Data Systems (CCSDS) and represents the consensus
technical agreement of the participating CCSDS Member Agencies. The procedure for
review and authorization of CCSDS Recommendations is detailed in the Procedures Manual
for the Consultative Committee for Space Data Systems, and the record of Agency
participation in the authorization of this document can be obtained from the CCSDS
Secretariat at the address below.

This document is published and maintained by:

CCSDS Secretariat
Space Communications and Navigation Office, 7L70
Space Operations Mission Directorate
NASA Headquarters
Washington, DC 20546-0001, USA
CCSDS 913.1-B-1 Page i September 2008
SPACE LINK EXTENSION—INTERNET PROTOCOL FOR TRANSFER SERVICES
STATEMENT OF INTENT
The Consultative Committee for Space Data Systems (CCSDS) is an organization officially
established by the management of its members. The Committee meets periodically to address
data systems problems that are common to all participants, and to formulate sound technical
solutions to these problems. Inasmuch as participation in the CCSDS is completely
voluntary, the results of Committee actions are termed Recommended Standards and are
not considered binding on any Agency.
This Recommended Standard is issued by, and represents the consensus of, the CCSDS
members. Endorsement of this Recommendation is entirely voluntary. Endorsement,
however, indicates the following understandings:
o Whenever a member establishes a CCSDS-related standard, this standard will be in
accord with the relevant Recommended Standard. Establishing such a standard
does not preclude other provisions which a member may develop.
o Whenever a member establishes a CCSDS-related standard, that member will
provide other CCSDS members with the following information:
-- The standard itself.
-- The anticipated date of initial operational capability.
-- The anticipated duration of operational service.
o Specific service arrangements shall be made via memoranda of agreement. Neither
this Recommended Standard nor any ensuing standard is a substitute for a
memorandum of agreement.
No later than five years from its date of issuance, this Recommended Standard will be
reviewed by the CCSDS to determine whether it should: (1) remain in effect without change;
(2) be changed to reflect the impact of new technologies, new requirements, or new
directions; or (3) be retired or canceled.
In those instances when a new version of a Recommended Standard is issued, existing
CCSDS-related member standards and implementations are not negated or deemed to be
non-CCSDS compatible. It is the responsibility of each member to determine when such
standards or implementations are to be modified. Each member is, however, strongly
encouraged to direct planning for its new standards and implementations towards the later
version of the Recommended Standard.
CCSDS 913.1-B-1 Page ii September 2008
SPACE LINK EXTENSION—INTERNET PROTOCOL FOR TRANSFER SERVICES
FOREWORD
Through the process of normal evolution, it is expected that expansion, deletion, or
modification of this document may occur. This Recommended Standard is therefore subject
to CCSDS document management and change control procedures, which are defined in the
Procedures Manual for the Consultative Committee for Space Data Systems. Current
versions of CCSDS documents are maintained at the CCSDS Web site:
http://www.ccsds.org/
Questions relating to the contents or status of this document should be addressed to the
CCSDS Secretariat at the address indicated on page i.
CCSDS 913.1-B-1 Page iii September 2008
SPACE LINK EXTENSION—INTERNET PROTOCOL FOR TRANSFER SERVICES
At time of publication, the active Member and Observer Agencies of the CCSDS were:

Member Agencies
– Agenzia Spaziale Italiana (ASI)/Italy.
– British National Space Centre (BNSC)/United Kingdom.
– Canadian Space Agency (CSA)/Canada.
– Centre National d’Etudes Spatiales (CNES)/France.
– China National Space Administration (CNSA)/People’s Republic of China.
– Deutsches Zentrum für Luft- und Raumfahrt e.V. (DLR)/Germany.
– European Space Agency (ESA)/Europe.
– Federal Space Agency (FSA)/Russian Federation.
– Instituto Nacional de Pesquisas Espaciais (INPE)/Brazil.
– Japan Aerospace Exploration Agency (JAXA)/Japan.
– National Aeronautics and Space Administration (NASA)/USA.

Observer Agencies
– Austrian Space Agency (ASA)/Austria.
– Belgian Federal Science Policy Office (BFSPO)/Belgium.
– Central Research Institute of Machine Building (TsNIIMash)/Russian Federation.
– Centro Tecnico Aeroespacial (CTA)/Brazil.
– Chinese Academy of Sciences (CAS)/China.
– Chinese Academy of Space Technology (CAST)/China.
– Commonwealth Scientific and Industrial Research Organization (CSIRO)/Australia.
– Danish National Space Center (DNSC)/Denmark.
– European Organization for the Exploitation of Meteorological Satellites
(EUMETSAT)/Europe.
– European Telecommunications Satellite Organization (EUTELSAT)/Europe.
– Hellenic National Space Committee (HNSC)/Greece.
– Indian Space Research Organization (ISRO)/India.
– Institute of Space Research (IKI)/Russian Federation.
– KFKI Research Institute for Particle & Nuclear Physics (KFKI)/Hungary.
– Korea Aerospace Research Institute (KARI)/Korea.
– MIKOMTEK: CSIR (CSIR)/Republic of South Africa.
– Ministry of Communications (MOC)/Israel.
– National Institute of Information and Communications Technology (NICT)/Japan.
– National Oceanic and Atmospheric Administration (NOAA)/USA.
– National Space Organization (NSPO)/Chinese Taipei.
– Naval Center for Space Technology (NCST)/USA.
– Space and Upper Atmosphere Research Commission (SUPARCO)/Pakistan.
– Swedish Space Corporation (SSC)/Sweden.
– United States Geological Survey (USGS)/USA.
CCSDS 913.1-B-1 Page iv September 2008
SPACE LINK EXTENSION—INTERNET PROTOCOL FOR TRANSFER SERVICES
DOCUMENT CONTROL
Document Title Date Status
CCSDS Space Link Extension—Internet September Original issue
913.1-B-1 Protocol for Transfer Services, 2008
Recommended Standard, Issue 1
CCSDS 913.1-B-1 Page v September 2008
SPACE LINK EXTENSION—INTERNET PROTOCOL FOR TRANSFER SERVICES
CONTENTS
Section Page
1  INTRODUCTION . 1-1

1.1  PURPOSE . 1-1
1.2  SCOPE . 1-1
1.3  APPLICABILITY . 1-2
1.4  RATIONALE . 1-2
1.5  DOCUMENT STRUCTURE . 1-2
1.6  DEFINITIONS, NOMENCLATURE, AND CONVENTIONS . 1-4
1.7  REFERENCES . 1-7

2  DESCRIPTION OF THE INTERNET SLE PROTOCOL. 2-1

2.1  INTRODUCTION . 2-1
2.2  ARCHITECTURAL MODEL . 2-1
2.3  AUTHENTICATION LAYER . 2-3
2.4  DATA ENCODING LAYER . 2-4
2.5  TRANSPORT MAPPING LAYER . 2-5
2.6  INTERFACES . 2-11
2.7  SECURITY ASPECTS OF THE INTERNET SLE PROTOCOL . 2-22

3  ISP1 MESSAGES AND PROCEDURES . 3-1

3.1  AUTHENTICATION LAYER . 3-1
3.2  DATA ENCODING LAYER . 3-3
3.3  TRANSPORT MAPPING LAYER . 3-4

4  TML STATE TABLE . 4-1

4.1  INTRODUCTION . 4-1
4.2  NOTATION . 4-1
4.3  STATES . 4-2
4.4  EVENTS . 4-2
4.5  PREDICATES . 4-4
4.6  ACTIONS . 4-4
4.7  STATE TABLE . 4-6

ANNEX A TML DIAGNOSTIC CODES (Normative) . A-1
ANNEX B DIFFERENCES WITH EARLIER IMPLEMENTATIONS
(Informative) .B-1
ANNEX C INDEX TO DEFINITIONS (Informative) . C-1
ANNEX D ACRONYMS (Informative) . D-1
ANNEX E INFORMATIVE REFERENCES (Informative) .E-1
CCSDS 913.1-B-1 Page vi September 2008
SPACE LINK EXTENSION—INTERNET PROTOCOL FOR TRANSFER SERVICES
CONTENTS (continued)
Figure Page
1-1  SLE Services and SLE API Documentation . 1-3
2-1  ISP1 Architecture Model . 2-1
3-1  ASN.1 Type for Generation of ‘the Protected’ . 3-2
3-2  ASN.1 Type for the Credentials Parameter . 3-3
3-3  Layout of a TML Message . 3-4
3-4  Layout of a TML Context Message . 3-5

Table
2-1  Primitives of the AL Interface . 2-11
2-2  Parameters of the Primitive AL-SLE-PDU . 2-11
2-3  Primitives of the DEL Interface . 2-12
2-4  Parameters of the Primitive DEL-SLE-PDU . 2-12
2-5  Primitives of the TML Data Transfer Interface . 2-12
2-6  Parameters of the Primitive TML-SLE-PDU . 2-13
2-7  Primitives of the TML Association Control Interface . 2-13
2-8  Parameters of the Primitive TML-CONNECT . 2-14
2-9  Parameters of the Primitive TML-PEER-ABORT . 2-14
2-10  Parameters of the Primitive TML-PROTOCOL-ABORT . 2-15
2-11  Primitives of the TML Listener Interface . 2-15
2-12  Parameters of the Primitive TML-START-LISTEN . 2-15
2-13  Parameters of the Primitive TML-STOP-LISTEN . 2-16
2-14  Primitives Used for the TCP-Interface . 2-19
2-15  Parameters of the Primitive TCP-PASSIVE-OPEN . 2-19
2-16  Parameters of the Primitive TCP-CONNECT . 2-20
2-17  Parameters of the Primitive TCP-DATA . 2-21
3-1  TML Message Type Identifiers . 3-5

CCSDS 913.1-B-1 Page vii September 2008
SPACE LINK EXTENSION—INTERNET PROTOCOL FOR TRANSFER SERVICES
1 INTRODUCTION
1.1 PURPOSE
The Space Link Extension (SLE) Reference Model (reference [1]) identifies a set of SLE
Transfer Services that enable missions to send forward space link data units to a spacecraft
and to receive return space link data units from a spacecraft. A subset of these services is
specified by the SLE Transfer Service Recommended Standards (references [2], [3], [4], [5],
and [6]). The SLE Transfer Service Recommended Standards specify
a) the operations necessary to provide the transfer service;
b) the parameter data associated with each operation;
c) the behaviors that result from the invocation of each operation; and
d) the relationship between, and the valid sequence of, the operations and resulting
behaviors.
However, they deliberately do not specify the methods or technologies required for
communications.
The purpose of this Recommended Standard is to define a protocol for transfer of SLE
Protocol Data Units (PDUs) defined in the SLE Transfer Service Recommended Standards
using the Internet protocols TCP (Transmission Control Protocol, reference [7]) and IP
(Internet Protocol, reference [8]) for data transfer and the Abstract Syntax Notation One
(ASN.1, references [9] and [10]) for data encoding. This protocol is referred to as the
Internet SLE Protocol One (ISP1).
1.2 SCOPE
This Recommended Standard defines a protocol for transfer of SLE PDUs between an SLE
user and an SLE provider system in terms of:
a) the procedures used to establish and release associations;
b) the messages exchanged on an established association;
c) the procedures used to monitor the status of data communication connections; and
d) the methods used to ensure that data are converted between different formats and
representations on different platforms.
It does not specify:
a) individual designs, implementations, or products;
b) the configuration of the data communications infrastructure, including configuration
of the TCP and IP protocols;
CCSDS 913.1-B-1 Page 1-1 September 2008
SPACE LINK EXTENSION—INTERNET PROTOCOL FOR TRANSFER SERVICES
c) the means by which addresses (IP addresses and TCP port numbers) are agreed,
assigned, and communicated.
This Recommended Standard responds to the requirements imposed by the Recommended
Standards for SLE transfer services that were available when this Recommended Standard
was released. The protocol specified in this Recommended Standard conforms to the
requirements on data communication services set forth in those Recommended Standards.
1.3 APPLICABILITY
1.3.1 APPLICABILITY OF THIS RECOMMENDED STANDARD
This Recommended Standard provides a basis for the development of real systems that
implement the Internet SLE Protocol. It is applicable for systems acting as an SLE service
user or SLE service provider.
1.3.2 LIMITS OF APPLICABILITY
This Recommended Standard specifies the Internet SLE Protocol that may be applied by an
SLE System for inter-Agency cross support. It is neither a specification of, nor a design for,
real systems that may be implemented for the control and monitoring of existing or future
missions.
1.4 RATIONALE
The goal of this Recommended Standard is to create a standard for interoperability between
the tracking stations and/or ground data handling systems of various agencies and the users
of SLE transfer services based on the technologies TCP/IP and ASN.1.
1.5 DOCUMENT STRUCTURE
1.5.1 ORGANIZATION
This document is organized as follows:
a) section 1 presents the purpose, scope, applicability and rationale of this
Recommended Standard and lists the definitions, conventions, and references used
throughout the Recommended Standard;
b) section 2 describes the Internet SLE Protocol by means of an architectural model
identifying individual protocol layers and the interfaces to higher layers;
c) section 3 specifies the messages exchanged via ISP1 and the procedures to be applied
for connection establishment and release and for data transfer;
CCSDS 913.1-B-1 Page 1-2 September 2008
SPACE LINK EXTENSION—INTERNET PROTOCOL FOR TRANSFER SERVICES
d) section 4 specifies the state table for the protocol;
e) annex A provides ISP1-specific diagnostic codes for the SLE PEER-ABORT
operation;
f) annex B describes differences with earlier implementations of ISP1;
g) annex C lists all terms used in this document and identifies where they are defined;
h) annex D lists all acronyms used within this document;
i) annex E contains a list of informative reference documents.
1.5.2 SLE SERVICES DOCUMENTATION TREE
This Recommended Standard is part of a suite of documents specifying the SLE services.
The SLE services constitute one of the three types of Cross Support Services:
a) Part 1: SLE Services;
b) Part 2: Ground Domain Services;
c) Part 3: Ground Communications Services.
The basic organization of the SLE services documentation is shown in figure 1-1. The
various documents are described in the following subsections.
Space Link Extension
Cross Support
Cross Support Concept SLE Executive
Reference Model
Part 1: SLE Services Summary
Part 1: SLE Services
SLE Transfer Services
Forward SLE Service Return SLE Service Internet Protocol for SLE Service
Specifications Specifications Transfer Services Management Suite
Recommended Recommended
Legend: Report (Green) Report (Yellow)
Standard (Blue) Practice (Magenta)

Figure 1-1: SLE Services and SLE API Documentation
a) Cross Support Concept—Part 1: Space Link Extension Services (reference [E2]), a
Report introducing the concepts of cross support and the SLE services;
CCSDS 913.1-B-1 Page 1-3 September 2008
SPACE LINK EXTENSION—INTERNET PROTOCOL FOR TRANSFER SERVICES
b) Cross Support Reference Model—Part 1: Space Link Extension Services
(reference [1]), a Recommended Standard that defines the framework and
terminology for the specification of SLE services;
c) Forward SLE Service Specifications, a set of Recommended Standards that will
provide specification of all forward link SLE services;
d) Return SLE Service Specifications, a set of Recommended Standards that will provide
specification of all return link SLE services;
e) Internet Protocol for Transfer Services, this Recommended Standard;
f) SLE Service Management Specifications, a set of Recommended Standards that
establish the basis of SLE service management.
1.6 DEFINITIONS, NOMENCLATURE, AND CONVENTIONS
1.6.1 DEFINITIONS
1.6.1.1 Definitions from the SLE Reference Model
This Recommended Standard makes use of the following terms defined in reference [1]:
a) initiator;
b) operation;
c) responder;
d) service user (user);
e) service provider (provider);
f) SLE protocol data unit (SLE-PDU);
g) SLE transfer service instance (service instance).
1.6.1.2 Definitions from SLE Transfer Service Specifications
This Recommended Standard makes use of the following terms defined in references [2], [3],
[4], [5], and [6]:
a) association;
b) communications service;
c) confirmed operation;
d) invocation;
e) parameter (of an operation);
CCSDS 913.1-B-1 Page 1-4 September 2008
SPACE LINK EXTENSION—INTERNET PROTOCOL FOR TRANSFER SERVICES
f) port identifier;
g) return;
h) unconfirmed operation.
1.6.1.3 Definitions from TCP/IP
This Recommended Standard makes use of the following terms defined in references [7] and [8]:
a) Internet Protocol (IP);
b) IP address;
c) port (of TCP);
d) port number;
e) Transmission Control Protocol (TCP);
f) segment (of TCP);
g) socket.
1.6.1.4 Definitions from Abstract Syntax Notation One
This Recommended Standard makes use of the following terms defined in references [9] and [10]:
a) Abstract Syntax Notation One (ASN.1);
b) Basic Encoding Rules (BER);
c) Distinguished Encoding Rules (DER);
d) encoding rules (of ASN.1);
e) encoding;
f) module (of ASN.1).
1.6.1.5 Definitions from OSI Basic Reference Model
This Recommended Standard makes use of the following terms defined in reference [13]:
a) abstract syntax;
b) primitive;
c) (protocol) layer;
d) transfer syntax.
CCSDS 913.1-B-1 Page 1-5 September 2008
SPACE LINK EXTENSION—INTERNET PROTOCOL FOR TRANSFER SERVICES
1.6.1.6 Additional Definitions
1.6.1.6.1 General
For the purposes of this Recommended Standard, the following definitions also apply.
1.6.1.6.2 (SLE) Application
An application is a software entity in an SLE user system or an SLE provider system that
makes use of the ISP1 protocol, as distinguished from the software implementing the
protocol layers defined in this Recommended Standard. The application is considered to
implement the ‘higher layers’ defined in the architectural model in section 2.
1.6.1.6.3 Local Application
The local application is the application implementing the higher layers interfacing with a
given instance of an ISP1 implementation.
1.6.1.6.4 Peer Application
The peer application is the application that communicates with the local application via the
ISP1 protocol. The peer application is typically located on a remote network, but may also be
located on the local network, or even on the same host as the local application.
1.6.1.6.5 Application Identifier
The application identifier is the authority identifier of the application by which the
application is identified in the BIND invocation and the BIND return.
NOTE – For an initiating SLE application, the application identifier is the initiator-
identifier, and for a responding SLE application, the application identifier is the
responder-identifier.
1.6.2 NOMENCLATURE
The following nomenclature applies throughout this Recommended Standard:
a) the words ‘shall’ and ‘must’ imply a binding and verifiable specification;
b) the word ‘should’ implies an optional, but desirable, specification;
c) the word ‘may’ implies an optional specification;
d) the words ‘is’, ‘are’, and ‘will’ imply statements of fact.
CCSDS 913.1-B-1 Page 1-6 September 2008
SPACE LINK EXTENSION—INTERNET PROTOCOL FOR TRANSFER SERVICES
1.6.3 CONVENTIONS
The Internet SLE Protocol is specified by a layered architecture model in which the
interfaces between the layers are defined using abstract service primitives, roughly following
the concepts in the OSI Basic Reference Model (reference [13]).
A service primitive is a signal optionally associated with a set of parameters that is generated
by one layer and consumed by another (adjacent) layer. The direction in which the
information is passed is defined by one of the following:
request a primitive that is passed from the higher layer to the lower layer;
indication a primitive that is passed from the lower layer to the higher layer;
response a primitive generated by the higher layer in response to an indication of the
same type;
confirmation a primitive generated by the lower layer in response to a request of the same
type.
For every service primitive, the following specifications are provided:
a) the name of the primitive;
b) the uses of the primitive (request, indication, response, confirmation);
c) the parameters associated with each of these uses.
In addition, the conditions under which the source emits a primitive and the tasks that the
receiver shall perform are described.
In this Recommended Standard, primitive names are capitalized and are followed by the
specific use in lowercase letters. The primitive name is prefixed by the identifier of the layer
that defines the interface, e.g., ‘TML-CONNECT-indication’. In the state table in section 4,
the prefix is omitted in order to avoid clashes with the notation used in these tables.
1.7 REFERENCES
The following documents contain provisions which, through reference in this text, constitute
provisions of this Recommended Standard. At the time of publication, the editions indicated
were valid. All documents are subject to revision, and users of this Recommended Standard
are encouraged to investigate the possibility of applying the most recent editions of the
documents indicated below. The CCSDS Secretariat maintains a register of currently valid
CCSDS Recommended Standards.
NOTE – A list of informative references is provided in annex E.
[1] Cross Support Reference Model—Part 1: Space Link Extension Services.
Recommendation for Space Data System Standards, CCSDS 910.4-B-2. Blue Book.
Issue 2. Washington, D.C.: CCSDS, October 2005.
CCSDS 913.1-B-1 Page 1-7 September 2008
SPACE LINK EXTENSION—INTERNET PROTOCOL FOR TRANSFER SERVICES
[2] Space Link Extension—Return All Frames Service Specification. Recommendation for
Space Data System Standards, CCSDS 911.1-B-2. Blue Book. Issue 2. Washington,
D.C.: CCSDS, December 2004.
[3] Space Link Extension—Return Channel Frames Service Specification. Recommendation
for Space Data System Standards, CCSDS 911.2-B-1. Blue Book. Issue 1.
Washington, D.C.: CCSDS, December 2004.
[4] Space Link Extension—Return Operational Control Fields Service Specification.
Recommendation for Space Data System Standards, CCSDS 911.5-B-1. Blue Book.
Issue 1. Washington, D.C.: CCSDS, December 2004.
[5] Space Link Extension—Forward CLTU Service Specification. Recommendation for
Space Data System Standards, CCSDS 912.1-B-2. Blue Book. Issue 2. Washington,
D.C.: CCSDS, December 2004.
[6] Space Link Extension—Forward Space Packet Service Specification. Recommendation
for Space Data System Standards, CCSDS 912.3-B-1. Blue Book. Issue 1.
Washington, D.C.: CCSDS, December 2004.
[7] J. Postel. Transmission Control Protocol. STD 7. Reston, VA: ISOC, September 1981.
[8] J. Postel. Internet Protocol. STD 5. Reston, VA: ISOC, September 1981.
[9] Information Technology—Abstract Syntax Notation One (ASN.1): Specification of
Basic Notation. International Standard, ISO/IEC 8824-1:2002. 3rd ed. Geneva: ISO,
2002.
[10] Information Technology—ASN.1 Encoding Rules: Specification of Basic Encoding
Rules (BER), Canonical Encoding Rules (CER) and Distinguished Encoding Rules
(DER). International Standard, ISO/IEC 8825-1:2002. 3rd ed. Geneva: ISO, 2002.
[11] Information Technology—Open Systems Interconnection—The Directory: Public-Key
and Attribute Certificate Frameworks. International Standard, ISO/IEC 9594-8:2001.
4th ed. Geneva: ISO, 2001.
[12] Secure Hash Standard. Federal Information Processing Standards Publication 180-1.
Gaithersburg, MD: NIST, 1995.
[13] Time Code Formats. Recommendation for Space Data System Standards, CCSDS
301.0-B-3. Blue Book. Issue 3. Washington, D.C.: CCSDS, January 2002.
[14] Information Technology—Open Systems Interconnection—Basic Reference Model:
The Basic Model. International Standard, ISO/IEC 7498-1. 2nd ed. Geneva: ISO,
1994.
CCSDS 913.1-B-1 Page 1-8 September 2008
TML Association
Control Interface
TML Listener Interface
Internet SLE Protocol Layer
SPACE LINK EXTENSION—INTERNET PROTOCOL FOR TRANSFER SERVICES
2 DESCRIPTION OF THE INTERNET SLE PROTOCOL
2.1 INTRODUCTION
This section describes a layered model of a system supporting the Internet SLE Protocol One
and introduces the main concepts by describing each layer and the interfaces between the
layers. Detailed specifications are provided in section 3, which references the concepts,
layers, and interfaces described by this model. It is stressed that this model has the sole
purpose of supporting the specifications in this Recommended Standard and is not intended
to suggest any specific design of a real implementation.
The discussion in this section assumes that the reader is familiar with the CCSDS
Recommended Standards for Space Link Extension transfer services provided by references
[2], [3], [4], [5], and [6], and assumes a general background on the Internet protocols,
especially on TCP (reference [7]).
2.2 ARCHITECTURAL MODEL
The architectural model used to specify the Internet SLE Protocol is shown in figure 2-1.
Higher Layers
Authentication Layer (AL)
Data Encoding Layer (DEL)
Transport Mapping Layer (TML)
Transmission Control Protocol (TCP)
Internet Protocol (IP)
Figure 2-1: ISP1 Architecture Model
CCSDS 913.1-B-1 Page 2-1 September 2008
SPACE LINK EXTENSION—INTERNET PROTOCOL FOR TRANSFER SERVICES
The Higher Layers represent the functionality specified by the Recommended Standards for
SLE transfer services (references [2], [3], [4], [5], and [6]), including in particular:
a) preparation of SLE protocol data units to be sent to the peer application;
b) analysis and processing of the SLE protocol data units received from the peer
application;
c) implementation of the state tables defined in the applicable Recommended Standard
for the SLE transfer service being provided or used.
The Internet SLE Protocol Layer is further decomposed into the following sub-layers:
a) The Authentication Layer (AL) is responsible for generating and analyzing the
credentials specified in the Recommended Standards for SLE transfer services. For
this purpose this Recommended Standard specifies use of the simple authentication
scheme defined in reference [11] and the Secure Hash Function (SHA-1) defined in
reference [12].
b) The Data Encoding Layer (DEL) is responsible for encoding of SLE protocol data
units received from higher layers and decoding of protocol data units received from
the peer application. For this purpose, this Recommended Standard specifies use of
the ASN.1 syntax defined by reference [9] and of the ASN.1 Basic Encoding Rules
(BER) defined by reference [10].
c) The Transport Mapping Layer (TML) handles the interface to the Transmission
Control Protocol (TCP) specified by reference [7].
ISP1 maps one TCP connection to one ISP1 association, which is used by the higher layers
for one SLE association as specified by the Recommended Standards for SLE transfer
services. ISP1 provides data encoding and decoding services but does not process SLE
protocol data units in any other respect.
For implementations assuming the responder role, the Transport Mapping Layer provides a
service to listen for incoming TCP connection requests. It therefore provides an interface by
which higher layers can request to start and stop listening for a specified SLE responder port
identifier, which the TML maps to an IP address and a TCP port number.
Except for the interface to control listening, all interfaces refer to one association only. ISP1
association establishment and release involves only the Transport Mapping Layer. Once the
association has been established, all SLE protocol data units are passed through the Data
Encoding Layer and the Authentication Layer.
ISP1 requires a number of configuration parameters for its operation, which are identified in
the following subsections. This Recommended Standard does not specify how these
parameters are defined, agreed, stored, and made available to the implementation of the ISP1.
CCSDS 913.1-B-1 Page 2-2 September 2008
SPACE LINK EXTENSION—INTERNET PROTOCOL FOR TRANSFER SERVICES
2.3 AUTHENTICATION LAYER
The ISP1 Authentication Layer (AL) receives SLE protocol data units from the higher layers
and adds the credentials parameter if required. Likewise, it receives decoded protocol data
units from the Data Encoding Layer and verifies that the credentials match the security
attributes of the peer application. If authentication is not used for a given service instance or
for a given PDU, the Authentication Layer passes the protocol data unit to the next layer
without modification or analysis.
For generation and analysis of the credentials, the Authentication Layer uses the simple
authentication scheme specified by reference [11], which is based on a secret password and a
message digest generated from that password, the time at which the credentials were
generated, and a random number. For the secure one-way hash function, required for this
scheme, the Secure Hash Function (SHA-1) specified by reference [12] is used.
If authentication fails for a PDU received from the peer application, the Authentication Layer
informs the higher layers, which are expected to handle this event as specified by the
Recommended Standards for SLE transfer services.
The Authentication Layer requires the following service instance configuration parameter for
its operation:
– authentication-level, defined by the Recommended Standards for SLE transfer
services, which can have the values
a) ‘all’: all invocations and returns, except the invocation of PEER-ABORT, shall
be authenticated;
b) ‘bind’: only the BIND invocation and return shall be authenticated;
c) ‘none’: no invocation or return shall be authenticated.
If the authentication-level is set to ‘all’ or ‘bind’ the Authentication Layer requires the
following additional configuration parameters:
a) the identifier of the local application;
b) the password of the local application;
c) the identifier of the peer application;
d) the password of the peer application;
e) the maximum time allowed between generation of the credentials by the invoker of an
SLE operation and verification of the credentials by the performer.
CCSDS 913.1-B-1 Page 2-3 September 2008
SPACE LINK EXTENSION—INTERNET PROTOCOL FOR TRANSFER SERVICES
NOTE – If the local application assumes the initiator role for the BIND operation, the
identifier of the local application is the initiator-identifier and the identifier of the
peer application is the responder-identifier defined by the Recommended
Standards for SLE transfer services. Otherwise, the identifier of the local
application is the responder-identifier and the identifier of the peer application is
the initiator-identifier.
2.4 DATA ENCODING LAYER
The ISP1 Dat
...