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Avionics Full-Duplex Switched Ethernet
Avionics Full-Duplex Switched Ethernet (AFDX) is a data network, patented by international aircraft manufacturer Airbus, for safety-critical applications that utilizes dedicated bandwidth while providing deterministic quality of service (QoS). AFDX is a registered trademark by Airbus in several countries worldwide, including Europe.〔(【引用サイトリンク】 title=AFDX )〕 The AFDX data network is based on Ethernet technology using commercial off-the-shelf (COTS) components. The AFDX data network is a specific implementation of ARINC Specification 664 Part 7, a profiled version of an IEEE 802.3 network per parts 1 & 2, which defines how commercial off-the-shelf networking components will be used for future generation Aircraft Data Networks (ADN). The six primary aspects of an AFDX data network include full duplex, redundancy, deterministic, high speed performance, switched and profiled network.
==History==
Many commercial aircraft use the ARINC 429 standard developed in 1977 for safety-critical applications. ARINC 429 utilizes a unidirectional bus with a single transmitter and up to twenty receivers. A data word consists of 32 bits communicated over a twisted pair cable using the Bipolar Return-to-Zero Modulation. There are two speeds of transmission: high speed operates at 100 kbit/s and low speed operates at 12.5 kbit/s. ARINC 429 operates in such a way that its single transmitter communicates in a point-to-point connection, thus requiring a significant amount of wiring which amounts to added weight.
Another standard, ARINC 629, introduced by Boeing for the 777 provided increased data speeds of up to 2 Mbit/s and allowing a maximum of 120 data terminals. This ADN operates without the use of a bus controller thereby increasing the reliability of the network architecture. The drawback is that it requires custom hardware which can add significant cost to the aircraft. Because of this, other manufactures did not openly accept the ARINC 629 standard.
AFDX was designed as the next-generation aircraft data network. Basing on standards from the IEEE 802.3 committee (commonly known as Ethernet) allows commercial off-the-shelf hardware to reduce costs and development time. AFDX is one implementation of deterministic Ethernet defined by ARINC Specification 664 Part 7. AFDX was developed by Airbus Industries for the A380, initially to address real-time issues for flight-by-wire system development. Building on the experience from the A380, the Airbus A350 also uses an AFDX network, with avionics and systems supplied by Rockwell Collins. Airbus and its EADS parent company have made AFDX licenses available through the EADS Technology Licensing initiative, including agreements with Selex ES〔“(Selex ES to partner with Airbus on mission management systems AFDX )” (Press release). Selex ES. 2013-6-19. Retrieved 2013-7-30.〕 and Vector Informatik〔“(Vector signs agreement for licensed use of Airbus-developed AFDX technology )” (Press release). Vector. 2013-2-19. Retrieved 2013-7-30.〕 GmbH. A similar implementation of deterministic Ethernet is used on the Boeing 787 Dreamliner. AFDX bridges the gap on reliability of guaranteed bandwidth from the original ARINC 664 standard. It utilizes a cascaded star topology network, where each switch can be bridged together to other switches on the network. By utilizing this form of network structure, AFDX is able to significantly reduce wire runs thus reducing overall aircraft weight. Additionally, AFDX provides dual link redundancy and Quality of Service (QoS).
抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』
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