delay-tolerant networking

{{further|History of delay-tolerant networking}}

In the 1970s, spurred by the decreasing size of computers, researchers began developing technology for routing between non-fixed locations of computers. While the field of ad hoc routing was inactive throughout the 1980s, the widespread use of wireless protocols reinvigorated the field in the 1990s as mobile ad hoc networking (MANET) and vehicular ad hoc networking became areas of increasing interest.

Concurrently with (but separate from) the MANET activities, DARPA had funded NASA, MITRE and others to develop a proposal for the Interplanetary Internet (IPN). Internet pioneer Vint Cerf and others developed the initial IPN architecture, relating to the necessity of networking technologies that can cope with the significant delays and packet corruption of deep-space communications. In 2002, Kevin Fall started to adapt some of the ideas in the IPN design to terrestrial networks and coined the term delay-tolerant networking and the DTN acronym. A paper published in 2003 SIGCOMM conference gives the motivation for DTNs.[http://conferences.sigcomm.org/sigcomm/2003/papers.html#p27-fall A Delay-Tolerant Network Architecture for Challenged Internets], K. Fall, SIGCOMM, August 2003. The mid-2000s brought about increased interest in DTNs, including a growing number of academic conferences on delay and disruption-tolerant networking, and growing interest in combining work from sensor networks and MANETs with the work on DTN. This field saw many optimizations on classic ad hoc and delay-tolerant networking algorithms and began to examine factors such as security, reliability, verifiability, and other areas of research that are well understood in traditional computer networking.

{{further|Routing in delay-tolerant networking}}

The ability to transport, or route, data from a source to a destination is a fundamental ability all communication networks must have. Delay and disruption-tolerant networks (DTNs), are characterized by their lack of connectivity, resulting in a lack of instantaneous end-to-end paths. In these challenging environments, popular ad hoc routing protocols such as AODV{{Citation | last1 = Perkins | first1 = C. | last2 = Royer | first2 = E. | contribution = Ad hoc on-demand distance vector routing | title = The Second IEEE Workshop on Mobile Computing Systems and Applications | year = 1999}} and DSR{{Citation | last1 = Johnson | first1 = D. | last2 = Maltz | first2 = D. | contribution = Dynamic source routing in ad hoc wireless networks | pages = 153–181 | title = Mobile Computing | year = 1996 | publisher = Kluwer Academic}} fail to establish routes. This is due to these protocols trying to first establish a complete route and then, after the route has been established, forward the actual data. However, when instantaneous end-to-end paths are difficult or impossible to establish, routing protocols must take to a "store and forward" approach, where data is incrementally moved and stored throughout the network in hopes that it will eventually reach its destination.John Burgess, Brian Gallagher, David Jensen, and Brian Neil Levine. MaxProp: Routing for vehicle-based disruption-tolerant networks. In Proc. IEEE INFOCOM, April 2006.{{cite conference |author=Philo Juang |author2=Hidekazu Oki |author3=Yong Wang |author4=Margaret Martonosi |author5=Li Shiuan Peh |author6=Daniel Rubenstein |book-title=Proceedings of the 10th international conference on Architectural support for programming languages and operating systems |title=Energy-efficient computing for wildlife tracking: Design tradeoffs and early experiences with ZebraNet |pages=96–107 |year=2002 |doi=10.1145/605397.605408 |isbn=978-1-58113-574-9 |s2cid=1078542 }}{{cite journal |first1=Augustin |last1=Chaintreau |first2=Pan |last2=Hui |first3=Jon |last3=Crowcroft |first4=Christophe |last4=Diot |first5=Richard |last5=Gass |first6=James |last6=Scott |title=Impact of human mobility on opportunistic forwarding algorithms |journal=IEEE Transactions on Mobile Computing |volume=6 |issue=6 |pages=606–620 |year=2007 |doi=10.1109/TMC.2007.1060 |s2cid=206745317 }} A common technique used to maximize the probability of a message being successfully transferred is to replicate many copies of the message in the hope that one will succeed in reaching its destination.{{Citation | last1 = Vahdat | first1 = Amin | last2 = Becker | first2 = David | contribution = Epidemic routing for partially connected ad hoc networks | title = Technical Report CS-2000-06 | publisher = Duke University | year = 2000}} This is feasible only on networks with large amounts of local storage and internode bandwidth relative to the expected traffic. In many common problem spaces, this inefficiency is outweighed by the increased efficiency and shortened delivery times made possible by taking maximum advantage of available unscheduled forwarding opportunities. In others, where available storage and internode throughput opportunities are more tightly constrained, a more discriminate algorithm is required.

In efforts to provide a shared framework for algorithm and application development in DTNs, {{IETF RFC |4838|5050 |leadout=and}} were published in 2007 to define a common abstraction to software running on disrupted networks. Commonly known as the Bundle Protocol, this protocol defines a series of contiguous data blocks as a bundle—where each bundle contains enough semantic information to allow the application to make progress where an individual block may not. Bundles are routed in a store and forward manner between participating nodes over varied network transport technologies (including both IP and non-IP based transports). The transport layers carrying the bundles across their local networks are called bundle convergence layers. The bundle architecture therefore operates as an overlay network, providing a new naming architecture based on Endpoint Identifiers (EIDs) and coarse-grained class of service offerings.

Protocols using bundling must leverage application-level preferences for sending bundles across a network. Due to the store and forward nature of delay-tolerant protocols, routing solutions for delay-tolerant networks can benefit from exposure to application-layer information. For example, network scheduling can be influenced if application data must be received in its entirety, quickly, or without variation in packet delay. Bundle protocols collect application data into bundles that can be sent across heterogeneous network configurations with high-level service guarantees. The service guarantees are generally set by the application level, and the {{IETF RFC |5050}} Bundle Protocol specification includes "bulk", "normal", and "expedited" markings.

In October 2014 the Internet Engineering Task Force (IETF) instantiated a [https://datatracker.ietf.org/wg/dtn/about/ Delay Tolerant Networking working group] to review and revise the protocol specified in {{IETF RFC |5050}}. The Bundle Protocol for CCSDS{{Cite book|url=https://public.ccsds.org/Pubs/734x2b1.pdf|title=CCSDS Bundle Protocol Specification|publisher=CCSDS|year=2015|location=Washington, D.C.}} is a profile of RFC 5050 specifically addressing the Bundle Protocol's utility for data communication in space missions.

As of January 2022, the IETF published the following RFCs related to BPv7: {{IETF RFC |9171|9172|9173|9174}}.

In January 2025, {{IETF RFC |9713|}} was published, which updates RFC 9171.

Addressing security issues has been a major focus of the bundle protocol. Possible attacks take the form of nodes behaving as a "black hole" or a "flooder".{{Cite book|last1=Bucur|first1=Doina|last2=Iacca|first2=Giovanni|last3=Squillero|first3=Giovanni|last4=Tonda|first4=Alberto|title=Applications of Evolutionary Computation |chapter=Black Holes and Revelations: Using Evolutionary Algorithms to Uncover Vulnerabilities in Disruption-Tolerant Networks |date=2015|editor-last=Mora|editor-first=Antonio M.|editor2-last=Squillero|editor2-first=Giovanni|volume=9028|series=Lecture Notes in Computer Science|language=en|publisher=Springer International Publishing|pages=29–41|doi=10.1007/978-3-319-16549-3_3|isbn=978-3-319-16549-3|hdl=11572/196441|hdl-access=free}}{{Cite journal|last1=Bucur|first1=Doina|last2=Iacca|first2=Giovanni|date=2017-09-01|title=Improved search methods for assessing Delay-Tolerant Networks vulnerability to colluding strong heterogeneous attacks|journal=Expert Systems with Applications|volume=80|pages=311–322|doi=10.1016/j.eswa.2017.03.035|issn=0957-4174|hdl=11572/196740|s2cid=37476103 |url=https://research.utwente.nl/en/publications/58e2e72e-c9eb-4fc4-b254-9f30969cc8ba |hdl-access=free}}

Security concerns for delay-tolerant networks vary depending on the environment and application, though authentication and privacy are often critical. These security guarantees are difficult to establish in a network without continuous bi-directional end-to-end paths between devices because the network hinders complicated cryptographic protocols, hinders key exchange, and each device must identify other intermittently visible devices.{{Cite journal|last1=Kate|first1=Aniket|last2=Zaverucha|first2=Greg|last3=Hengartner|first3=Urs|date=2007|title=Anonymity and security in delay tolerant networks|journal=3rd International Conference on Security and Privacy in Communication Networks (SecureComm 2007)|citeseerx=10.1.1.71.8314 }}{{Cite book|last1=Farrell|first1=S.|last2=Cahill|first2=V.|title=2nd IEEE International Conference on Space Mission Challenges for Information Technology (SMC-IT'06) |chapter=Security Considerations in Space and Delay Tolerant Networks |date=2006-07-17|chapter-url=https://ieeexplore.ieee.org/document/1659530|pages=8 pp.–38|doi=10.1109/SMC-IT.2006.66|isbn=0-7695-2644-6 |s2cid=2191529 }} Solutions have typically been modified from mobile ad hoc network and distributed security research, such as the use of distributed certificate authorities[http://infoscience.epfl.ch/record/54941/files/01542053.pdf DICTATE: DIstributed CerTification Authority with probabilisTic frEshness for Ad Hoc Networks] and PKI schemes. Original solutions from the delay-tolerant research community include: 1) the use of identity-based encryption, which allows nodes to receive

information encrypted with their public identifier;"Practical security for disconnected nodes" Seth, A. Keshav, S. 1st IEEE ICNP Workshop on Secure Network Protocols (NPSec), 2005. and 2) the use of tamper-evident tables with a gossiping protocol;[http://www.cs.ucl.ac.uk/staff/D.Quercia/publications/quercia08mobirate.pdf MobiRate: Making Mobile Raters Stick to their Word]. ACM Ubicomp 2008

There are a number of implementations of the Bundle Protocol:

The main implementation of BPv6 are listed below. A number of other implementations exist.

• [https://github.com/nasa/HDTN High-rate DTN]—C++17 - based; performance-optimized DTN; runs directly on Linux and Windows.
• NASA Interplanetary Overlay Network (ION)—Written in C; designed to run on a wide variety of platforms; conforms to restrictions for space flight software (e.g. no dynamic memory allocation).
• [https://github.com/ibrdtn IBR-DTN]—C++ - based; runs on routers with OpenWRT; also contains Java applications (router and user apps) for use on Android.
• [https://github.com/delay-tolerant-networking/DTN2 DTN2]—C++ - based; designed to be a reference / learning / teaching implementation of the Bundle Protocol.
• [https://github.com/nasa/DTNME DTN Marshal Enterprise (DTNME)]—C++ - based; Enterprise solution; designed as an operational DTN implementation. Currently used in ISS operations. DTNME is a single implementation supporting both BPv6 and BPv7.

The draft of BPv7 lists the following implementations.{{Cite journal|last1=Fall|first1=Kevin|last2=Birrane|first2=Edward|last3=Burleigh|first3=Scott|title=Bundle Protocol Version 7|url=https://tools.ietf.org/html/draft-ietf-dtn-bpbis-27.html|access-date=2020-10-29|newspaper=Ietf Datatracker|date=28 October 2020 |language=en}}

• [https://github.com/nasa/HDTN High-rate DTN]—C++17 - based; performance-optimized DTN; runs directly on Linux and Windows.
• [https://upcn.eu/ μPCN]—C; built upon the POSIX API as well as FreeRTOS and intended to run on low-cost micro satellites.
• PyDTN—Python; developed by X-works and during the IETF 101 Hackathon.
• [https://github.com/RightMesh/Terra/ Terra]—Java; developed in the context of terrestrial DTN.
• [https://github.com/dtn7/dtn7-go dtn7-go]—Go; implementation focused on easy extensibility and suitable for research.
• [https://github.com/dtn7/dtn7-rs/ dtn7-rs]—Rust; intended for environments with limited resources and performance requirements.
• NASA Interplanetary Overlay Network (ION)—C; intended to be usable in embedded environments including spacecraft flight computers.
• [https://github.com/nasa/DTNME DTN Marshal Enterprise (DTNME)]—C++ - based; Enterprise solution; designed as an operational DTN implementation. Currently used in ISS operations. DTNME is a single implementation supporting both BPv6 and BPv7.
• [https://github.com/nasa/bplib NASA BPLib]-C; A Bundle Protocol library and associated applications by Goddard Space Flight Center. Intended for general use, particularly in space flight applications, integration with [https://cfs.gsfc.nasa.gov/ cFS] (core Flight System), and other applications where store-and-forward capabilities are needed. First time will be used on PACE mission [https://www.nasa.gov/communicating-with-missions/delay-disruption-tolerant-networking/]

Various research efforts are currently investigating the issues involved with DTN:

• The [https://web.archive.org/web/20050209141050/http://www.dtnrg.org/ Delay-Tolerant Networking Research Group].
• The [https://web.archive.org/web/20100620194630/http://tier.cs.berkeley.edu/ Technology and Infrastructure for Developing Regions] project at UC Berkeley
• The [https://web.archive.org/web/20100815015702/http://www.tslab.ssvl.kth.se/csd/projects/092106/ Bytewalla] research project at the [https://web.archive.org/web/20110901170251/http://vm-199.xen.ssvl.kth.se/csdlive/content/projects Royal Institute of Technology, KTH]
• The KioskNet research project at the University of Waterloo.
• The [http://dome.cs.umass.edu/umassdieselnet DieselNet] {{Webarchive|url=https://web.archive.org/web/20220317144638/http://dome.cs.umass.edu/umassdieselnet |date=2022-03-17 }} research project at the University of Massachusetts Amherst, Amherst.
• The [https://resilinets.org/ ResiliNets Research Initiative] at the University of Kansas and Lancaster University.
• The [http://haggleproject.org Haggle]{{Dead link|date=January 2025}} EU research project.
• The Space Internetworking Center EU/FP7 project at the Democritus University of Thrace.
• The [https://web.archive.org/web/20090118001032/http://www.n4c.eu/ N4C] EU/FP7 research project.
• The [https://web.archive.org/web/20160304032027/http://www.darpa.mil/STO/strategic/wireless.html WNaN] DARPA project.
• The [http://www.ibr.cs.tu-bs.de/projects/emma/ EMMA] and [http://www.ibr.cs.tu-bs.de/projects/optracom/ OPTRACOM] projects at TU Braunschweig
• The [http://www.netlab.hut.fi/u/jo/dtn/index.html DTN] at Helsinki University of Technology.
• The [http://www-valoria.univ-ubs.fr/SARAH SARAH] {{Webarchive|url=https://web.archive.org/web/20181225233244/http://www-valoria.univ-ubs.fr/SARAH |date=2018-12-25 }} project, funded by the French National Research Agency ([http://www.agence-nationale-recherche.fr/ ANR]).
• The development of the [https://casa-irisa.univ-ubs.fr/dodwan DoDWAN platform] at [https://www.univ-ubs.fr Université Bretagne Sud].
• The [http://anr-crowd.lip6.fr/ CROWD] {{Webarchive|url=https://web.archive.org/web/20110721005820/http://anr-crowd.lip6.fr/ |date=2011-07-21 }} project, funded by the French National Research Agency ([http://www.agence-nationale-recherche.fr/ ANR]).
• The [https://web.archive.org/web/20100515140646/http://podnet.ee.ethz.ch/ PodNet] project at KTH Stockholm and ETH Zurich.

Some research efforts look at DTN for the Interplanetary Internet by examining use of the Bundle Protocol in space:

• The [http://personal.ee.surrey.ac.uk/Personal/L.Wood/saratoga/ Saratoga] project at the University of Surrey, which was the first to test the bundle protocol in space on the UK-DMC Disaster Monitoring Constellation satellite in 2008.[http://info.ee.surrey.ac.uk/Personal/L.Wood/publications/ Use of the Delay-Tolerant Networking Bundle Protocol from Space] {{Webarchive|url=https://web.archive.org/web/20080513145740/http://info.ee.surrey.ac.uk/Personal/L.Wood/publications/ |date=2008-05-13 }}, L. Wood et al., Conference paper IAC-08-B2.3.10, 59th International Astronautical Congress, Glasgow, September 2008.[http://www.sstl.co.uk/News_and_Events/Latest_News/?story=1254 UK-DMC satellite first to transfer sensor data from space using 'bundle' protocol] {{Webarchive|url=https://web.archive.org/web/20120426220355/http://www.sstl.co.uk/News_and_Events/Latest_News/?story=1254 |date=2012-04-26 }}, press release, Surrey Satellite Technology Ltd, 11 September 2008.[http://www.engineeringbritain.com/space/archives/190-CLEO-Orbital-Internet-earns-Time-Magazine-award.html CLEO Orbital Internet earns Time Magazine award] {{Webarchive|url=https://web.archive.org/web/20081207033626/http://www.engineeringbritain.com/space/archives/190-CLEO-Orbital-Internet-earns-Time-Magazine-award.html |date=2008-12-07 }}, Robin Wolstenholme, Surrey Satellite Technology Ltd space blog, 14 November 2008.
• NASA JPL's Deep Impact Networking (DINET) Experiment on board the Deep Impact/EPOXI spacecraft.[http://www.technologyreview.com/communications/21601/?a=f A Better Network for Outer Space] {{Webarchive|url=https://web.archive.org/web/20120331041302/http://www.technologyreview.com/communications/21601/?a=f |date=2012-03-31 }}, Brittany Sauser, MIT Technology Review, 27 October 2008.[http://www.nasa.gov/home/hqnews/2008/nov/HQ_08-298_Deep_space_internet.html NASA Successfully Tests First Deep Space Internet] {{Webarchive|url=https://web.archive.org/web/20101124220808/http://www.nasa.gov/home/hqnews/2008/nov/HQ_08-298_Deep_space_internet.html |date=2010-11-24 }}, NASA press release 08-298, 18 November 2008.
• BioServe Space Technologies, one of the first payload developers to adopt the DTN technology, has utilized their CGBA (Commercial Generic Bioprocessing Apparatus) payloads on board the ISS, which provide computational/communications platforms, to implement the DTN protocol.Jenkins, Andrew; Kuzminsky, Sebastian; Gifford, Kevin K.; Holbrook, Mark; Nichols, Kelvin; Pitts, Lee. (2010). [http://www-bioserve.colorado.edu/wp2/wp-content/uploads/2010/05/DTN-Initial-Flight-Tests-Results-v0.035.pdf "Delay/Disruption-Tolerant Networking: Flight Test Results from the International Space Station."] {{webarchive|url=https://web.archive.org/web/20110902182525/http://www-bioserve.colorado.edu/wp2/wp-content/uploads/2010/05/DTN-Initial-Flight-Tests-Results-v0.035.pdf |date=2011-09-02 }} IEEE Aerospace Conference.Gifford, Kevin K.; Jenkins, Andrew; Holbrook, Mark; Kuzminsky, Sebastian; Nichols, Kelvin; Pitts, Lee. (2010). [http://www-bioserve.colorado.edu/wp2/wp-content/uploads/2010/09/AIAA-2010-2173-810.pdf "DTN Implementation and Utilization Options on the International Space Station."] {{Webarchive|url=https://web.archive.org/web/20110902182641/http://www-bioserve.colorado.edu/wp2/wp-content/uploads/2010/09/AIAA-2010-2173-810.pdf |date=2011-09-02 }} American Institute of Aeronautics and Astronautics.][http://bioserve.colorado.edu The Automation Group at BioServe Space Technologies] University of Colorado, Boulder.
• NASA, ESA Use Experimental Interplanetary Internet to Test Robot From International Space Station {{Cite web|url=http://www.nasa.gov/home/hqnews/2012/nov/HQ_12-391_DTN.html|title = NASA, ESA Use Experimental Interplanetary Internet to Test Robot from International Space Station|date = 7 April 2015}}

• Logistical Networking
• Message switching
• Store and forward

{{reflist|30em}}

{{Channel access methods}}

{{DEFAULTSORT:Delay-Tolerant Networking}}

Category:Network architecture

Category:Network protocols