Delay Tolerant Networking Birds of a Feather 1300 -1700, 4 October 2007 Heppenheim, Germany 4 October, 2007 CCSDS DTN Bo. F -- Heppenheim
Original Agenda Time Topic Presenter 1300 -1400 -1500 Current state of the IRTF DTN Protocol. How good a fit is it for CCSDS? Documents (Arch, Protocol Spec) DTN 2 ION Protocol overhead Documents Security 1500 -1510 Solicitation of interest: do we think CCSDS should invest in standardizing DTN technology and protocol(s)? Poll for agency support 1510 -1600 Assuming interest, how to incorporate DTN into CCSDS (adopt, adapt [issues? ], …)? Discussion 1600 -1700 4 October, 2007 Possible space mission drivers for DTN technology: MERs ESA Others? Draft DTN WG Charter Discussions Agency support (resources) Schedule (1 year? ) How to specify? 2 implementation req’t? s Discussion CCSDS DTN Bo. F -- Heppenheim Keith Scott, Scott Burleigh 2
Proposed Agenda Partial Order First Topic DTN Overview – DTN as a formalization of long-term store-and-forward relay technologies – Overlay network on top of [transport | network | link] – DTN as a refactorization and generalization of CFDP with additional capabilities – Relationship to Mars Interoperability WG Second Current state of DTN Protocol and Implementations – Specifications (Architecture, Protocol, Security) – DTN 2 Reference Implementation – Interplanetary Overlay Network (ION) Architectures and interoperability points DTN activities Last DTN WG Charter Discussions (assumes interest in WG formation) – Agency support (resources) – How to incorporate DTN into CCSDS (adopt, adapt [issues? ], …)? – Schedule? 4 October, 2007 CCSDS DTN Bo. F -- Heppenheim 3
DTN in a Nutshell “Postal model” of Communications Store and Forward, minimal interactivity source Link Decoupling Routing destination Persistent Storage Disrupted Region DTN provides network services across disruption and massive differences in delay and bandwidth 4 October, 2007 CCSDS DTN Bo. F -- Heppenheim 5
DTN Overlay Network persistent storage Application DTN Gateway Application DTN DTN Transport Transport Network Network Link Link Phy Phy Planetary-local Network Deep Space Terrestrial Network • DTN interconnects disparate networking regions – Operates above regional transport layer stacks – Allows flexibility to adapt to specific environments 4 October, 2007 CCSDS DTN Bo. F -- Heppenheim 6
DTN Overlay Network for Deep Space (No Relays Yet) persistent storage CFDP / AMS DTN Gateway CFDP / AMS DTN DTN Transport Network Link Phy Phy Planetary-local Network TCP LTP Pkts AOS Deep Space TCP IP IP Link Phy Terrestrial Network • For space, DTN can run over CCSDS protocols – Could also run directly over space packets, e. g. 4 October, 2007 CCSDS DTN Bo. F -- Heppenheim 7
DTN Accounting: Custody Transfer persistent storage Custody Transfers CFDP / AMS DTN Gateway CFDP / AMS DTN DTN Transport Network Link Phy Phy Planetary-local Network TCP LTP Pkts AOS TCP IP IP Link Phy Deep Space Terrestrial Network • DTN reliability is via custody transfer – Once custody has been accepted by a downstream bundle, the current custodian is safe to remove it 4 October, 2007 CCSDS DTN Bo. F -- Heppenheim 8
DTN Accounting: Status Reports persistent storage Bundle status reports from intermediate nodes CFDP / AMS DTN Gateway CFDP / AMS DTN DTN Transport Network Link Phy Phy Planetary-local Network TCP LTP Pkts AOS Deep Space TCP IP IP Link Phy Terrestrial Network • DTN provides a number of status reports for accountability from intermediate nodes – Time of (receipt, custody, forwarding, deletion) – Settable on a per-bundle basis 4 October, 2007 CCSDS DTN Bo. F -- Heppenheim 9
DTN Accounting: Delivery Report persistent storage End-to-End Delivery Receipt CFDP / AMS DTN Gateway CFDP / AMS DTN DTN Transport Network Link Phy Phy Planetary-local Network TCP LTP Pkts AOS Deep Space TCP IP IP Link Phy Terrestrial Network • One of the status reports is a delivery receipt, indicating the bundle has been delivered to the destination application 4 October, 2007 CCSDS DTN Bo. F -- Heppenheim 10
DTN’s Derived Design Rules • Don’t plow the same ground twice – hold the gains you’ve achieved • Don’t engage in unnecessary chit-chat – build complete transactions and make network accesses count • Don’t depend on information from inaccessible / remote places if you can avoid it – build a sequence of local control operations and use late binding • Don’t force homogeneity – allow different network components to use environmentally-relevant optimizations 4 October, 2007 CCSDS DTN Bo. F -- Heppenheim 11
4 October, 2007 Circa 2002 Demonstration CCSDS DTN Bo. F -- Heppenheim 12
Relationship to Mars Interoperability Working Group • Mars Interop. WG standardizes the parameters and options for the various data links, concentrating on the relay orbiter-to-remote surface interface – Reliability, accounting, file transfer left to upper layers – DTN can provide these 4 October, 2007 CCSDS DTN Bo. F -- Heppenheim 13
Space Relay Requirements • Support for automated multi-hop data relay between remote elements and Earth – Short local control loops enable finer-grained decision making and better performance – Cross-support between different agencies’ assets • CCSDS-wide naming / addressing scheme to allow unified and unambiguous identification of communications endpoints – Supports cross-support between different agencies’ assets – Something for SANA to manage 4 October, 2007 CCSDS DTN Bo. F -- Heppenheim 14
Why DTN? • Capabilities: – – – Reliable delivery via custody transfer Built-in accounting mechanisms (time of receipt, time of forward, …) Precedence Extensibility Security that protects the infrastructure • DTN Provides more than CFDP alone – Additional per-hop accounting plus end-to-end delivery notifications – DTN supports fragmentation and delivery over multiple parallel paths – Security • Cleanly extend terrestrial endpoint past end of space data link (cross -support of IP on the ground would make this cross-supportable) • Generalization (refactoring) of CFDP capabilities to provide both message and file paradigms 4 October, 2007 CCSDS DTN Bo. F -- Heppenheim 15
Current State of DTN • Delay Tolerant Networking is being developed under the Internet Research Task Force – Architecture document: RFC 4838 – Bundle Protocol Specification: In process to be published as an informational RFC • Optional reliability via custody transfer • End-to-end and hop-by-hop security mechanisms – Security • Draft-irtf-dtnrg-sec-overview-03 • Draft-irtf-dtnrg-bundle-security-04 – Bundle Authentication – Payload Security – Payload Encryption • Implementations – – DTN 2 reference implementation (available from dtnrg. org) JPL Interplanetary Overlay Network (ION) implementation TKK implementation for Symbian cellphone Georgia Tech. Net implementation 4 October, 2007 CCSDS DTN Bo. F -- Heppenheim 17
Interoperability at IETF 67 November 5 -10, 2006 TKK Language Platform DTN 2 MITRE* BBN* GA Tech ION C++ C++, Java C# C Mac. Os Symbian and Linux cellphone on PC and Nokia 770 Linux on PC; external router Linux on. NET on PC; Win 32 & external CL Linux on adapter PC & PDA Linux on PC Custody Transfer Status Reports TCP CL UDP CL 4 October, 2007 CCSDS DTN Bo. F -- Heppenheim * Derived from DTN 2 RI 18
Topology for IETF 67 Interoperability Tests udp Demmer-mac tcp BBN, java. 11, RI. 31, RI ext CL Demmer-pc udp. 12 Pocket, C#. 63 udp jpl 1. 23, ION udp mitre 2. 52, RI 770 tcp udp. 42, RI on Nokia 770 War, C#. 61 udp Charon, C# udp mitre. 62, GA Tech. 51, RI ext Rtr “Hey, these status reports are kinda useful. ” 4 October, 2007 tcp 9300, C++. 41, Symbian Status reports direct to demmer-mac Destination dtn: //9300. dtn/send CCSDS DTN Bo. F -- Heppenheim 19
Features Tested at IETF 67 • End-to-end transmission – With and without custody transfer – Moving between convergence layers • Payload sizes varying from 6 to 1545 bytes – Raw text messages – Email-format messages destined for Symbian phone • All status reports generated and parsed – Report-to different from source endpoint • Partial test of TTL expiration 4 October, 2007 CCSDS DTN Bo. F -- Heppenheim 20
Bundle Protocol Headers (Blocks) Bundle Protocol Headers CBHE Compressed Bundle Header Encoding 32 bits Version 32 bits Flags Block Destination Source length Scheme SSP Scheme Source Report-to Custodian SSP Scheme SSP scheme Custodian Creation Stamp 1 SSP Creation Lifetime Stamp 2 Dictionary Length Version Primary Bundle Block Control Flags Payload Destination Element # Service # Report-to Element # Service # Creation Stamp 1 Block Type Fragment Offset Payload Block Length Primary Bundle Block Lifetime Total ADU length Control Flags Total ADU length Block Type Scheme Number Source Service # Creation Stamp 2 Dictionary Length=0 Dictionary (Variable) Fragment Offset Block length Source Element # Custodian Element # Flags Block Length Bundle Payload Block Dictionary allows references to address information that may occur multiple times (e. g. src. and dst. schemes the same; src and report-to endpoints the same). Dashed boxes are SDNVs. 4 October, 2007 CCSDS DTN Bo. F -- Heppenheim 22
DTN Activities • NASA effort to demonstrate flight-ready DTN by 2010 – Target of TRL 8 by 2010 • Active research community – Testing the protocol – Maintaining multiple interoperable implementations – Developing additional capabilities • ‘Space-Oriented’ Implementation and Applications – ION Implementation – Remote AMS over DTN 4 October, 2007 CCSDS DTN Bo. F -- Heppenheim 23
How DTN Might Fit Within CCSDS: Architectures and Interoperability • Slides with strawman architectures and interoperability points 4 October, 2007 CCSDS DTN Bo. F -- Heppenheim 24
Strawman DTN Architecture Downlink • Minimal DTN deployment • No additional interoperability requirements beyond current plans Application DTN TCP Space Packets Space Pkts Prox-1 Remote Element 4 October, 2007 X-Support Xfer Svcs AOS Remote Relay X-Support Agency A Space Pkts Ground Station Deep-Space X-Support Agency B IP AOS Ether Control Center Terrestrial X-Support 1 Agency C Agency A CCSDS DTN Bo. F -- Heppenheim 26
Strawman DTN Architecture Downlink • DTN in relay orbiter • Significant performance increase Application DTN DTN Space Packets Space Pkts Prox-1 Remote Element 4 October, 2007 Space Pkts X-Support Xfer Svcs AOS Remote Relay X-Support Agency A TCP Ground Station Deep-Space X-Support Agency B IP AOS Ether Control Center Terrestrial X-Support 1 Agency C Agency A CCSDS DTN Bo. F -- Heppenheim 27
Strawman DTN Architecture Downlink • Fully deployed DTN • Additional terrestrial interoperability shown Application DTN DTN Space Packets Space Pkts Prox-1 Remote Element Remote Relay X-Support Agency A 4 October, 2007 Space Pkts Ground Station Deep-Space X-Support Agency B TCP X-Support Xfer Svcs AOS DTN TCP IP IP AOS Ether Control Center Terr. User Terrestrial X-Support 1 Agency C Terrestrial X-Support 2 Agency D CCSDS DTN Bo. F -- Heppenheim Agency A 28
Strawman DTN Architecture Uplink • Minimal DTN over TC deployment • No additional interoperability requirements beyond current plans Application DTN TCP Space Packets Space Pkts Prox-1 Remote Element 4 October, 2007 X-Support Xfer Svcs TC Remote Relay X-Support Agency A Space Pkts Ground Station Deep-Space X-Support Agency B IP TC Ether CLTUs Control Center Terrestrial X-Support 1 Agency C Agency A CCSDS DTN Bo. F -- Heppenheim 30
Strawman DTN Architecture Uplink • DTN at remote relay Application DTN DTN Space Packets Space Pkts Prox-1 Remote Element 4 October, 2007 Space Pkts X-Support Xfer Svcs TC Remote Relay X-Support Agency A TCP Ground Station Deep-Space X-Support Agency B IP TC Ether CLTUs Control Center Terrestrial X-Support 1 Agency C Agency A CCSDS DTN Bo. F -- Heppenheim 31
Strawman DTN Architecture Uplink • Fully deployed DTN • Additional terrestrial interoperability shown • DTN boundaries can be security boundaries; control center checking Application DTN DTN Space Packets Space Pkts Prox-1 Remote Element Remote Relay X-Support Agency A 4 October, 2007 Space Pkts Ground Station Deep-Space X-Support Agency B TCP X-Support Xfer Svcs TC DTN TCP IP IP TC Ether Control Center Terr. User CLTUs Terrestrial X-Support 1 Agency C Terrestrial X-Support 2 Agency D CCSDS DTN Bo. F -- Heppenheim Agency A 32
Conclusions • Orbiter-Landed element interoperability is necessary but additional features are needed – Packets by themselves don’t provide reliability, mutli-packet ADU, or accountability – CFDP provides many but not all of these features under a ‘filespecific’ model • DTN generalizes CFDP functionality by refactoring it into its constituent parts (LTP, DTN, Application) and adds additional capabilities – More useful for SMC? • CCSDS can leverage work done by the DTN community – Demonstrated interoperability – Protocol extensions 4 October, 2007 CCSDS DTN Bo. F -- Heppenheim 33
Draft WG Deliverables (From Group Discussion) • DTN Green Book – Architecture • Compatibility w/ existing systems – Relationship between DTN and CFDP – Ops concepts • JAXA conops (source apps and time) – data recorder design – Mission Scenarios – Section on routing requirements / ideas or separate document on routing requirement s / ideas (no protocol book) • DTN bundle protocol (Blue Book) • LTP protocol (Blue Book) 4 October, 2007 CCSDS DTN Bo. F -- Heppenheim 39
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