2004 International Telemetering Conference20 October 2004 1

CCSDS FILE DELIVERY PROTOCOL

INTER-IMPLEMENTATION TESTING FINAL REPORT

TESTING OF A DTN PROTOCOL

RICHARD D. CARPER1

Consultant, Space Data Systems

MASSIMILIANO CICCONE2

European Space Agency

KATHY BRYAN ROCKWELL1

Jet Propulsion Laboratory,California Institute of Technology

1This work was performed in part at and under the direction of of the Jet Propulsion Laboratory, California Institute of Technology under a contract with the National Aeronautics and Space Administration.

2This work was performed in part at and under the direction of the European Space Agency.

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• The CCSDS has for over twenty years developed and promulgated space link standards for the use of the international space-faring community

• Over 250 spacecraft have used or are using these standards

• Some of the CCSDS member Agencies, most specifically JPL, are presently developing standards which will extend the Internet into the space data domain.

256 Missions now usingCCSDS Space Link Protocols

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CCSDS File Delivery Protocol (CFDP)

Provides international standard file delivery:

•in both reliable and expedited modes•across both short haul and Deep Space links•across single or multi-hop (store and forward) links• re-creates the user’s product directly for transfer to user’s processing•automated protocol improves link utilization and reduces operational costs and complexity

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Objectives of Interoperability Test Program

Objectives of the Test Program were to:

Validate the protocol specification

Clarify the wording of the specification, reducing the possibility of differing interpretations

Demonstrate the interoperability of independent implementations

Provide tested reference implementations for potential users

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Three Levels of CFDP Protocol Capability

Core Proceduresoperate point-to-point across a single link.

Extended Proceduresproviding an end-to-end store-and-forward functionality across an

arbitrary network, containing multiple links with disparate availability,

as well as subnetworks with heterogeneous protocols.

Store and Forward Overlay (SFO) ProceduresProvide an alternative to the Extended Procedures and operate at the

Application layer, utilizing only the Core Procedures

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Three Configurations for Testing

“Face-to-Face” Initial Tests

Worldwide Distributed Testing via the Internet

“Absentee Owner” Testing in a Protocol Testing Laboratory

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“Face-to-Face” Tests

The first Testing Workshop was hosted in May, 2000, at APL, Columbia, Maryland It was sufficiently productive that it resulted in a series of Workshops

Further face-to-face Workshops were held at DERA, Farnborough UK, in November 2000, and then at JPL, Pasadena, USA, in May, 2001

Following the Pasadena Workshop the testing migrated to what became a distributed international Inter-Agency Testbed, operating over the Internet

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CFDP Distributed Tests

The CFDP Core Procedures were tested in this configuration.15 Test Sessions of approximately 4 hours each were held with implementers and a proctor. 490 tests were conducted.Areas of the specification which were subject to different interpretations were found, but no true errors in the protocol

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Protocol Test Lab Tests

The Extended Procedures and the Store and Forward Overlay procedures were tested in the JPL Telecommunications Section’s Protocol Test Laboratory

Both the ESA implementation and the JPL implementation were installed (as multiple instances) in the Lab’s host systems.

Unlike previous tests, the software, set-up and tests were all conducted by Lab personnel, rather than by the Implementers.

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Protocol Test Lab Tests (2)

A special tool was developed by the ESA implementer which allowed him to receive hex dumps, via email, of PDUs causing problems and re-insert those PDUs into his local system at ESA ESTEC in Noordwijk, Holland, thus exactly recreating the problem encountered in the Lab at JPL in Pasadena.

This enabled a kind of “batch remote debugging” operation during the initial installation and start-up phase.

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Added Capabilities of a Test Lab

CFDP

User App

CFDP/UDP

Ethernet

CFDP

User App

CFDP/UDP

Ethernetinternet

CFDP

User App

CFDP

User App

CCSDS Link CCSDS Link

Radio Radio

Face-to-Face andDistributed TestingVia the Internet

Testing within aSpecialized Test Lab

Noisy,Noisy,AsymmetricAsymmetric

radio linkradio link

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Results of Testing

“Face-to-Face” Test ResultsThe CFDP Core Procedures were tested in this configuration. The tests were primarily developmental in nature, and were successful in terms of necessary precursor work and experience.

Distributed Test ResultsThe CFDP Core Procedures were tested in this configuration.15 Test Sessions of approximately 4 hours each were held with implementers and a proctor. 490 tests were conducted.Areas of the specification which were subject to different interpretations were found, but no true errors in the protocol

Protocol Test Lab ResultsThe CFDP Extended Procedures and the Store and Forward Overlay procedures were tested in this configuration. (RESULTS TO BE SUPPLIED)

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Lessons Learned

Testing of an in-design protocol by using independently created implementations greatly improves the protocol and the specification document, and increases confidence in them

Face-to-face testing workshops, distributed testing via the Internet, and testing in specialized Protocol Test Laboratories are all valuable and complimentary

To keep testing focused, organized, and moving, it is essential to have a set of common test plans/descriptions for all to use in inter-implementation testing

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Conclusions

The CFDP Interoperability Test Program -

Validated the protocol specification

Clarified the wording of the specification, reducing the possibility of differing interpretations

Demonstrated the interoperability of independent implementations

Provided tested reference implementations for potential users

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Untethered, disconnectedExtreme mass/power constraintsMobile, ad-hoc, self organizing

Space missions are increasingly moving from point-to-point to networked architectures -- internal to each spacecraft -- on and around other planetsJust like the terrestrial Internet, standardized space networking allows us to build low-cost, reusable infrastructure that can be shared by many diverse space missions

Mars Region 1

Mars Region 2

Mars Orbit Region

Terrestrial RegionDeep Space Backbone Region

A Step on the Road to Interplanetary DTNs

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Questions?