What is DTN (Disruption Tolerant Networking)?

Even with strong, reliable communication connectivity and ad-hoc MANET techniques, current systems often rely on either proprietary data and network protocols – locking the solution provider into one particular vendor – or are based on protocols intended for the terrestrial Internet.

While these have proven to be extremely capable in our day-to-day lives, the Internet (and the Internet Protocol or “IP” on which its based) make several significant assumptions which do not hold true in a mobile, globally spanning, non-deterministic environment such as global shipping and supply chain management.

What is required is a re-examination of a C3I architecture without the assumptions of traditional communications networking (connectedness, short delay, bidirectionality, etc.). Fortunately, industry, government, and academia have been examining this problem for quite some time. Emerging out of the need to perform command and control of deep space missions, and to address the inherent failings of the “traditional internet protocols” as networks become more mobile and more disconnected, Disruption Tolerant Networking (DTN) was conceived. Originally funded through a partnership between DARPA and NASA, researchers developed a set of network concepts and protocols to provide “highly reliable communications” in a delayed and disrupted environment – one in which broken links, slow data rates, and high delays are assumed as characteristics of the environment and not unusual failure cases.

What was developed is ideally suited for mobile, low SWAP, LPI/LPD networking that is also fully compatible with traditional networks such as those based on Link-16 and TCP/IP. Essentially a technique was developed to extend “fingers of the Internet” out to the edge cases where the broader architecture could not fit. In this case, we propose to extend “fingers of the Global Information Grid (GIG)” to the edge cases where the global supply chain resides.

Technology Maturity and Readiness

DTNs have been developed and deployed in many operational environments by NASA and other international space agencies, the NSF, many universities, and several emergent space companies. NASA’s operational use of DTN includes deploying the Bundle Protocol and its supporting infrastructure onboard the International Space Station as the primary path for science and engineering data to be exchanged with Earth. NASA’s Jet Propulsion Laboratory used DTN store and forward communications architectures form command, control, telemetry, and mission data return from its fleet of Mars spacecraft and rovers. DTN instances (including those developed by NASA) are available in the open source and have been rigorously tested and validated by the community – including certification for use in manned space flight.

DTN concepts are in use at the international McMurdo Base Research Station in Antarctica, providing reliable communications across intermittent SATCOM links between Antarctica and NSF headquarters. Additionally, this architecture uses both commercial and NASA TDRSS relay satellites which communicate in completely dissimilar ways in terms of frequency, modulation, channel coding, and packet structure.

Worldwide international standards bodies including the Internet Engineering Task Force (IETF), with responsibility for Internet standards, and the Consultative Committee for Space Data Systems (CCSDS), with responsibility for international space systems interoperability have established and codified standards for the protocols, behaviors, architectures, management, and validation of DTNs built upon the Bundle Protocol suite.

Depending on the application, DTNs are at a TRL between 6 and 9. 9 if you consider routine operations by the NSF and NASA; 6 if you need to extend the protocols and application suite for specific missions and purposes.