Evaluation of CCSDS File Delivery Protocol over Delay Tolerant Networks. Giorgos Papastergiou, Hellenic Aerospace Industry S.A, Schimatari, Greece Democritus University of Thrace , Xanthi, Greece E. Koutsogiannis and V. Tsaoussidis - PowerPoint PPT Presentation
International Workshop on Satellite and Space Communications 2009, IWSSC 2009, 9-11 September 2009, Siena, Italy Evaluation of CCSDS File Delivery Protocol over Delay Tolerant Networks Giorgos Papastergiou, Hellenic Aerospace Industry S.A, Schimatari, Greece Democritus University of Thrace , Xanthi, Greece E. Koutsogiannis and V. Tsaoussidis Department of Electrical and Computer Engineering, Democritus University of Thrace, Xanthi, Greece
Transcript
International Workshop on Satellite and Space Communications 2009, IWSSC 2009, 9-11 September 2009, Siena, Italy
Evaluation of CCSDS File Delivery Protocol over Delay Tolerant Networks
Giorgos Papastergiou,Hellenic Aerospace Industry S.A, Schimatari, Greece
Democritus University of Thrace , Xanthi, Greece
E. Koutsogiannis and V. TsaoussidisDepartment of Electrical and Computer Engineering, Democritus University of Thrace, Xanthi, Greece
Work summary
Investigation of how CFDP can serve as the file transfer protocol within the DTN architecture
Initial evaluation of its performance – integration of ESA/ESTEC CFDP with JPL ION DTN
implementation– Evaluation using a space-oriented Testbed
Conclusion: CFDP can rely on DTN for naming,
routing, SFO and reliability2
International Workshop on Satellite and Space Communications 2009, IWSSC 2009, 9-11 September 2009, Siena, Italy
What gap does this work fill in
During the last decade CCSDS has developed CFDP as a file transfer protocol for space communications
– CFDP is a ready-to-flight product– Future missions will support it– CFDP relies on current space infrastructure (SPP, TM/TC, AOS)
DTN will be the future communication architecture
When migrating to DTN how can we take advantage of the already developed CFDP protocol?
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Current state
Increased number of space elements need for more automated and flexible communications
Current space communication protocols rely on static routing,
– while the number of alternative communication paths in space increases
Space communication protocols have a rather cross-layer functionality
Protocols with cross-layer funcionality
Space Packet Protocol– is really an application layer artifact– has a simple naming mechanism (APID)– static routing through LDPs
CCSDS File Delivery Protocol– has transport layer functionalities as well– supports store-and-forward
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CCSDS File Delivery Protocol 1/2
Application Layer Protocol for file transferring
Transport Layer Functionalities– Two modes of operation (unacknowledged /
acknowledged mode)– Three file delivery services (Core / Extended
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CCSDS File Delivery Protocol 2/2
CFDP is unsuitable when communication complexity increases
– No dynamic routing– No file distribution through multiple relay points in
parallel– No advanced retransmission mechanisms– No end-to-end security
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Towards Delay Tolerant Networking
New protocols and mechanisms for routing and transfer reliability are needed in order to deal with:
– Alternative communication paths– Intermittent connectivity– Large propagation delays– High BER– Resource sharing among space agencies
DTN Architecture tends to dominate the field
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DTN Architecture
Store and Forward message switching
Custody Transfer
Reliability of lower layer (LTP, DS-TP, etc)
Proactive and Reactive Fragmentation
Flexible naming scheme with Late Binding
Dynamic Routing
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DTN Architecture
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The problem
Space agencies will continue to use current infrastructure – legacy mission support– financial reasons
Questions: – How CFDP cooperates with DTN?– Is there any functionality overlapping?– How it performs?
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CFDP and DTN comparison
Features CFDP DTN
File management Yes No
Reliability Yes Yes
SFO Yes Yes
Custody Transfer Yes* Yes
Global naming No Yes
Routing No Yes
Security No Yes
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Solution: keep all the file management features and
disable all other
Evaluation scenario
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COMNET lab’s space oriented communication Testbed
CFDP over DTN (ION)– Each CFDP PDU is encapsulated in
a “bundle”– CFDP at the endpoints
Simple 2-node topology
1Kbyte CFDP PDU size– Data aggregation/segmentation is
left to the underlying network
COMNET lab’s Testbed 1/2
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COMNET lab’s Testbed 2/2
Distributed nodes– COMNET Lab, DUTH, Xanthi, Greece– Hellenic Aerospace Industry, Athens, Greece– Massachusetts Institute of Technology, USA
Protocols Implemented:– ESA/ESTEC CFDP implementation– 2 Bundle Protocol Implementations (ION and DTN2)– LTP– CCSDS Space Packet Protocol (soon)
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Terrestrial and Geostationary links
CFDP/BP/TCP
10 MByte file size
1 Mbps/ 256 Kbps
50-300 ms propagation delay
0 – 10% PER
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Deep-space links
CFDP/BP/LTP and CFDP/UDP
5 and10 MByte file size
1 Mbps/ 256 Kbps
30 sec propagation delay
0 – 10% PER
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Conclusions
It is feasible to operate CFDP only as a file application protocol over DTN (ION)
Advantages of such integration could be :
– the exploitation of the advanced BP features (such as SFO, coarse grained reliability, routing, naming, fragmentation)
– the exploitation of the enhanced (re)transmission ability (LTP, DS-TP)
Further results are still needed to identify potential trade-offs and the mechanisms required to maximize performance
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Thank you
Any questions?
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References
ComNet Group: http://comnet.ee.duth.gr
ESA Project Site: http://www.hai- rt.gr/Projects/ExtendingInternet IntoSpace/ home.aspx
ESA DTN Testbed: C. Samaras, I. Komnios, D. Sotirios, E. Koutsogiannis, V. Tsaoussidis, G. Papastergiou and N. Peccia, "Extending Internet into Space – ESA DTN Testbed Implementation and Evaluation", 1st International Conference on Mobile Lightweight Wireless Systems, Workshop on Research activities funded by ESA in Greece, Athens, Greece, May 18-20, 2009.
DS-TP: Giorgos Papastergiou, Ioannis Psaras and Vassilis Tsaoussidis"Deep-Space Transport Protocol: A Novel Transport Scheme for Space DTNs"Computer Communications (COMCOM), Elsevier Science, Special Issue on Delay-/Disruption-Tolerant Networks, 2009.
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