Vint Cerf Details Interplanetary Plans for DTN

Vint Cerf joined Internet Evolution for a live chat yesterday during which he detailed his 10 years working on a new Internet protocol -- Disruption Tolerant Networking (DTN) -- built for interplanetary use. Ten years in, Cerf says the protocol will be "ready to deploy in operational scenarios" by the end of 2009.

(View the transcript of the live chat by following this link: Vint Cerf Live Chat.)

Cerf has been working as a visiting scientist with the Jet Propulsion Laboratory at NASA since 1998, the year Google (Nasdaq: GOOG) was born, and years before he took a position there in 2005. "Google is not exactly working with NASA on DTN -- this is just my 20 percent time effort that Google permits," Cerf told Internet Evolution.

The difference between DTN and the protocol Cerf helped create in the 1970s, TCP/IP, is that DTN uses a "store-and-forward" method that doesn't assume continuous connection from end-to-end. "TCP is intended for reliable delivery. It does not do well, however, in frequently disrupted networks where end-to-end communication cannot be maintained," said Cerf. "As to spectrum, DTN can theoretically run over any spectrum."

First tested successfully last November on Deep Space Impact, the technology will be used again in 2011 on the EPOXI spacecraft that is en route to visit a comet. (Cerf says this is the same spacecraft as the Deep Impact spacecraft, with a new name.) "Later, Mars missions are targeted for possible use of DTN," he added.

But DTN's deployments won't be limited to government space missions. Cerf noted that he and his team also ported DTN to Android, Google's mobile operating system, and are looking into testing it with Intelsat 14, a commercial satellite serving the American market. "So there might be some testing and experimentation in civilian environments in 2010. We have also tested in military tactical scenarios with good results."

Cerf also sees another potential application for DTN in oceanographic sensing. "Data would be stored in the ocean buoys or in sensors under the ocean surface. At intervals, data could be transferred to an orbiting satellite. That's what happens with today's rovers on Mars."

As DTN performs better in disrupted environments than TCP/IP, Cerf sees further potential for deployment in rural areas and has tested the technology with villagers in the northern part of Sweden.

But because of DTN's "store-and-forward" method, the protocol requires more and different storage than TCP. "DTN assumes that it can store content in the nodes -- that allows it to recover rapidly from link failures, but it does imply that packet/bundle content can be temporarily stored. IP does not make that assumption," said Cerf. "Flash storage may be too slow. There are new solid-state, random access recorders that are commonly used for space applications that might apply for DTN."

As far as DTN's potential as a successor to TCP here on the Earthly Web, Cerf wasn't conclusive. "It may persist for quite some time -- TCP/IP -- because it has shown ability to adapt to a dynamic range of over six orders of magnitude. However, I can imagine some interesting variations such as better use of broadcast media, rather than treating it as point-to-point as TCP/IP does."

To read the full transcript, including Cerf's concerns about malware, the future of Google's revenue stream, and the hold-up on IPv6, just click here: Vint Cerf Live Chat.

— Nicole Ferraro, Site Editor, Internet Evolution