|
The interplanetary internet (based on IPN, also called ''InterPlaNet'') is a conceived computer network in space, consisting of a set of network nodes that can communicate with each other.〔(The Interplanetary Internet ), Joab Jackson, IEEE Spectrum, August 2005.〕〔(Generation InterPlanetary Internet | SpaceRef — Your Space Reference )〕 Communication would be greatly delayed by the great interplanetary distances, so the IPN needs a new set of protocols and technology that are tolerant to large delays and errors.〔 Although the Internet as it is known today tends to be a busy ''network of networks'' with high traffic, negligible delay and errors, and a wired backbone, the interplanetary Internet is a store and forward ''network of internets'' that is often disconnected, has a wireless backbone fraught with error-prone links and delays ranging from tens of minutes to even hours, even when there is a connection.〔(The Interplanetary Internet: A Communications Infrastructure for Mars Exploration ) – 53rd International Astronautical Congress. ''The World Space Congress'', 19 Oct 2002/Houston, Texas〕 ==Development== Space communication technology has steadily evolved from expensive, one-of-a-kind point-to-point architectures, to the re-use of technology on successive missions, to the development of standard protocols agreed upon by space agencies of many countries. This last phase has gone on since 1982 through the efforts of the Consultative Committee for Space Data Systems (CCSDS),〔http://public.ccsds.org〕 a body composed of the major space agencies of the world. It has 11 member agencies, 22 observer agencies, and over 100 industrial associates. The evolution of space data system standards has gone on in parallel with the evolution of the Internet, with conceptual cross-pollination where fruitful, but largely as a separate evolution. Since the late 1990s, familiar Internet protocols and CCSDS space link protocols have integrated and converged in several ways, for example, the successful FTP file transfer to Earth-orbiting STRV 1B on January 2, 1996, which ran FTP over the CCSDS IPv4-like Space Communications Protocol Specifications (SCPS) protocols.〔(The Space Technology Research Vehicles: STRV-1a, b, c and d ), Richard Blott and Nigel Wells, AIAA Small Satellite Conference, Logan, Utah, 1996.〕〔Appendix F, (CCSDS 710.0-G-0.3: Space Communication Protocol Specification (SCPS) - Rationale, Requirements, and Application Notes ), Draft Green Book, Issue 0.3. April 1997.〕 Internet Protocol use without CCSDS has taken place on spacecraft, e.g., demonstrations on the UoSAT-12 satellite, and operationally on the Disaster Monitoring Constellation. Having reached the era where networking and IP on board spacecraft have been shown to be feasible and reliable, a forward-looking study of the bigger picture was the next phase. The Interplanetary Internet study at NASA's Jet Propulsion Laboratory (JPL) was started by a team of scientists at JPL led by Vinton Cerf and Adrian Hooke.〔(CCSDS.org — Meet the Area Directors — Adrian Hooke )〕 Cerf is one of the pioneers of the Internet on Earth, and currently holds the position of distinguished visiting scientist at JPL. Hooke is one of the directors of the CCSDS. While IP-like SCPS protocols are feasible for short hops, such as ground station to orbiter, rover-to-lander, lander-to-orbiter, probe-to-flyby, and so on, delay-tolerant networking is needed to get information from one region of the solar system to another. It becomes apparent that the concept of a "region" is a natural architectural factoring of the InterPlanetary Internet. A "region" is an area where the characteristics of communication are the same.〔(Interplanetary Internet )〕 Region characteristics include communications, security, the maintenance of resources, perhaps ownership, and other factors.〔 The Interplanetary Internet is a "network of regional internets." What is needed then, is a standard way to achieve end-to-end communication through multiple regions in a disconnected, variable-delay environment using a generalized suite of protocols. Examples of regions might include the terrestrial Internet as a region, a region on the surface of the moon or Mars, or a ground-to-orbit region. The recognition of this requirement led to the concept of a "bundle" as a high-level way to address the generalized Store-and-Forward problem. Bundles are an area of new protocol development in the upper layers of the OSI model, above the Transport Layer with the goal of addressing the issue of bundling store-and-forward information so that it can reliably traverse radically dissimilar environments constituting a "network of regional internets." Delay-tolerant networking (DTN) was designed to enable standardized communications over long distances and through time delays. At its core is something called the Bundle Protocol (BP), which is similar to the Internet Protocol, or IP, that serves as the heart of the Internet here on Earth. The big difference between the regular Internet Protocol (IP) and the Bundle Protocol is that IP assumes a seamless end-to-end data path, while BP is built to account for errors and disconnections — glitches that commonly plague deep-space communications.〔(Space Station Astronaut Drives Robot on Earth via 'Interplanetary Internet' )〕 Bundle Service Layering, implemented as the Bundling protocol suite for delay-tolerant networking, will provide general purpose delay-tolerant protocol services in support of a range of applications: custody transfer, segmentation and reassembly, end-to-end reliability, end-to-end security, and end-to-end routing among them. The Bundle Protocol was first tested in space on the UK-DMC satellite in 2008.〔(Use of the Delay-Tolerant Networking Bundle Protocol from Space ), L.Wood ''et al.'', Conference paper IAC-08-B2.3.10, 59th International Astronautical Congress, Glasgow, September 2008.〕〔(UK-DMC satellite first to transfer sensor data from space using 'bundle' protocol ), press release, Surrey Satellite Technology Ltd, 11 September 2008.〕 An example of one of these end-to-end applications flown on a space mission is the CCSDS File Delivery Protocol (CFDP), used on the comet mission, ''Deep Impact''. CFDP is an international standard for automatic, reliable file transfer in both directions. (CFDP should not be confused with Coherent File Distribution Protocol, which unfortunately has the same acronym and is an IETF-documented experimental protocol for rapidly deploying files to multiple targets in a highly networked environment.) In addition to reliably copying a file from one entity (such as a spacecraft or ground station) to another entity, CFDP has the capability to reliably transmit arbitrary small messages defined by the user, in the metadata accompanying the file, and to reliably transmit commands relating to file system management that are to be executed automatically on the remote end-point entity (such as a spacecraft) upon successful reception of a file. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Interplanetary Internet」の詳細全文を読む スポンサード リンク
|