What are the challenges to communication in extreme environments?
Among the challenges to be addressed are: large delay for transmissions resulting from either physical link properties or extended periods of network partitioning, routing capable of operating efficiently with frequently-disconnected, pre-scheduled, or opportunistic link availability, high per-link error rates making end-to-end reliability difficult, heterogeneous underlying network technologies (including non-IP-based internets), and application structure and security mechanisms capable of limiting network access prior to data transit in an environment where round-trip-times may be very large.
How was the group started?
DTNRG was formed in 2002 as a result of the observation that a non-interactive, asynchronous form of messaging service, able to operate over diverse types of networks, would be useful for several networks currently in use or being contemplated. Earlier work within IRTF's Interplanetary Internet Research Group (IPNRG) appeared to be a suitable basis for a generalization to networks other than those operating in deep space. IPNRG has since been moved to historical status within IRTF, yet remains active as part of CCSDS, a standards group concerned with protocols operating in space. IPNRG itself sprang out of the earlier Internet Society Interplanetary Internet Special Interest Group (IPNSIG), set up as part of the Internet Society, and now dormant.
The architecture originally conceived within IPNRG and developed further under the auspices of DTNRG proposes an alternative to the Internet TCP/IP end-to-end interactive delivery model and employs hop-by-hop storage and retransmission as a transport-layer overlay. It provides a messaging service interface conceptually similar to electronic mail, but generalized for application-independence and supported by specialized reliability and routing capabilities.
How does this group relate to IPNRG, the IETF, and the IRTF?
DTNRG is an IRTF-sponsored open research group. IRTF is the research-oriented relative of IETF. Prior to the chartering of DTNRG, the bundling architecture was developed within the Interplanetary Internet Research Group (IPNRG), which is now of 'historical' status within IRTF. Interest specifically in the Interplanetary Internet was originally established by the IPN Special Interest Group, and its members will continue to participate in CCSDS (a group responsible for data communications standards in space) and other efforts.
What other projects are dealing with similar issues?
The following links will take you to other projects that are dealing with similar issues. Some of these are using the product of DTNRG directly, and others are developing their own approaches:
If you would like your project linked-to here, please post some information about it to firstname.lastname@example.org.