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Avionics Full-Duplex Switched Ethernet (AFDX), also ARINC 664, is a data network, patented by international aircraft manufacturer
Airbus Airbus SE (; ; ; ) is a European Multinational corporation, multinational aerospace corporation. Airbus designs, manufactures and sells civil and military aerospace manufacturer, aerospace products worldwide and manufactures aircraft througho ...
, for safety-critical applications that utilizes dedicated bandwidth while providing deterministic
quality of service Quality of service (QoS) is the description or measurement of the overall performance of a service, such as a telephony or computer network, or a cloud computing service, particularly the performance seen by the users of the network. To quantitat ...
(QoS). AFDX is a worldwide registered trademark by Airbus. The AFDX data network is based on
Ethernet Ethernet () is a family of wired computer networking technologies commonly used in local area networks (LAN), metropolitan area networks (MAN) and wide area networks (WAN). It was commercially introduced in 1980 and first standardized in 198 ...
technology using
commercial off-the-shelf Commercial off-the-shelf or commercially available off-the-shelf (COTS) products are packaged or canned (ready-made) hardware or software, which are adapted aftermarket to the needs of the purchasing organization, rather than the commissioning of ...
(COTS) components. The AFDX data network is a specific implementation of
ARINC Aeronautical Radio, Incorporated (ARINC), established in 1929, was a major provider of transport communications and systems engineering solutions for eight industries: aviation, airports, defense, government, healthcare, networks, security, and t ...
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 Network Aircraft Data Network (ADN) is a concept introduced by the Airlines Electronics Engineering Committee (AEEC) in the ARINC 664 Specification. The specification proposes data networking standards recommended for use in commercial aircraft installat ...
s (ADN). The six primary aspects of an AFDX data network include
full duplex A duplex communication system is a point-to-point system composed of two or more connected parties or devices that can communicate with one another in both directions. Duplex systems are employed in many communications networks, either to allow ...
, redundancy, determinism, high speed performance, switched and profiled network.


History

Many commercial aircraft use the
ARINC 429 ARINC 429, "Mark33 Digital Information Transfer System (DITS)," is also known as the Aeronautical Radio INC. (ARINC) technical standard for the predominant avionics data bus used on most higher-end commercial and transport aircraft. It defines the ...
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 The ARINC 629 computer bus was introduced in May 1995 and is used on the Boeing 777. The ARINC 629 bus operates as a multiple-source, multiple-sink system; each terminal can transmit data to, and receive data from, every other terminal on the data b ...
, introduced by Boeing for the
777 777 may refer to: * 777 (number), a number * AD 777, a year of the Julian calendar * 777 BC, a year in the 8th century BC * Boeing 777, a commercial jet airliner :* Boeing 777X, the newer generation of the Boeing 777. Art and entertainment Alb ...
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 manufacturers 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 Ethernet () is a family of wired computer networking technologies commonly used in local area networks (LAN), metropolitan area networks (MAN) and wide area networks (WAN). It was commercially introduced in 1980 and first standardized in 198 ...
) 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 The Airbus A350 is a long-range, wide-body twin-engine jet airliner developed and produced by Airbus. The first A350 design proposed by Airbus in 2004, in response to the Boeing 787 Dreamliner, would have been a development of the A330 wi ...
also uses an AFDX network, with avionics and systems supplied by
Rockwell Collins Rockwell Collins was a multinational corporation headquartered in Cedar Rapids, Iowa, providing avionics and information technology systems and services to government agencies and aircraft manufacturers. It was formed when the Collins Radio Comp ...
.
Airbus Airbus SE (; ; ; ) is a European Multinational corporation, multinational aerospace corporation. Airbus designs, manufactures and sells civil and military aerospace manufacturer, aerospace products worldwide and manufactures aircraft througho ...
and its
EADS Airbus SE (; ; ; ) is a European multinational aerospace corporation. Airbus designs, manufactures and sells civil and military aerospace products worldwide and manufactures aircraft throughout the world. The company has three divisions: '' ...
parent company have made AFDX licenses available through the EADS Technology Licensing initiative, including agreements with
Selex ES Selex ES was a subsidiary of Finmeccanica S.p.A., active in the electronics and information technology business, based in Italy and the UK, and formed in January 2013, following Finmeccanica's decision to combine its existing SELEX Elsag and ...
and
Vector Informatik Vector Informatik develops software tools and components for networking of electronic systems based on the serial bus systems CAN, LIN, FlexRay, MOST, Ethernet, AFDX, ARINC 429,
GmbH. A of deterministic Ethernet is used on the Boeing
787 Dreamliner The Boeing 787 Dreamliner is an American wide-body jet airliner developed and manufactured by Boeing Commercial Airplanes. After dropping its unconventional Sonic Cruiser project, Boeing announced the conventional 7E7 on January 29, 2003, ...
. Multiple switches can be bridged together in a cascaded
star topology A star network is an implementation of a spoke–hub distribution paradigm in computer networks. In a star network, every host is connected to a central hub. In its simplest form, one central hub acts as a conduit to transmit messages. Th ...
. This type of network can significantly reduce wire runs, thus the weight of the aircraft. In addition, AFDX can provide
quality of service Quality of service (QoS) is the description or measurement of the overall performance of a service, such as a telephony or computer network, or a cloud computing service, particularly the performance seen by the users of the network. To quantitat ...
and dual link redundancy.


Overview of AFDX

AFDX adopted concepts such as the
token bucket The token bucket is an algorithm used in packet-switched and telecommunications networks. It can be used to check that data transmissions, in the form of packets, conform to defined limits on bandwidth and burstiness (a measure of the unevenness ...
from the telecom standards,
asynchronous transfer mode Asynchronous Transfer Mode (ATM) is a telecommunications standard defined by American National Standards Institute (ANSI) and ITU-T (formerly CCITT) for digital transmission of multiple types of traffic. ATM was developed to meet the needs of ...
(ATM), to fix the shortcomings of IEEE 802.3 Ethernet. By adding key elements from ATM to those already found in Ethernet, and constraining the specification of various options, a highly reliable full-duplex deterministic network is created providing guaranteed bandwidth and quality of service (QoS). Through the use of full-duplex Ethernet, the possibility of transmission collisions is eliminated. The network is designed in such a way that all critical traffic is prioritized using QoS policies so delivery, latency, and jitter are all guaranteed to be within set parameters. A highly intelligent switch, common to the AFDX network, is able to
buffer Buffer may refer to: Science * Buffer gas, an inert or nonflammable gas * Buffer solution, a solution used to prevent changes in pH * Buffering agent, the weak acid or base in a buffer solution * Lysis buffer, in cell biology * Metal ion buffer * ...
transmission and reception packets. Through the use of twisted pair or fiber optic cables, full-duplex Ethernet uses two separate pairs or strands for transmitting and receiving the data. AFDX extends standard Ethernet to provide high data integrity and deterministic timing. Further a redundant pair of networks is used to improve the system integrity (although a virtual link may be configured to use one or the other network only). It specifies interoperable functional elements at the following
OSI reference model The Open Systems Interconnection model (OSI model) is a conceptual model that 'provides a common basis for the coordination of SOstandards development for the purpose of systems interconnection'. In the OSI reference model, the communications ...
layers: *
Data link A data link is the means of connecting one location to another for the purpose of transmitting and receiving digital information (data communication). It can also refer to a set of electronics assemblies, consisting of a transmitter and a recei ...
( MAC and virtual link addressing concept); *
Network Network, networking and networked may refer to: Science and technology * Network theory, the study of graphs as a representation of relations between discrete objects * Network science, an academic field that studies complex networks Mathematics ...
( IP and ICMP); *
Transport Transport (in British English), or transportation (in American English), is the intentional movement of humans, animals, and goods from one location to another. Modes of transport include air, land (rail and road), water, cable, pipeline, an ...
( UDP and optionally TCP) * Application (network) (sampling, queuing,
SAP Sap is a fluid transported in xylem cells (vessel elements or tracheids) or phloem sieve tube elements of a plant. These cells transport water and nutrients throughout the plant. Sap is distinct from latex, resin, or cell sap; it is a separa ...
,
TFTP Trivial File Transfer Protocol (TFTP) is a simple lockstep File Transfer Protocol which allows a client to get a file from or put a file onto a remote host. One of its primary uses is in the early stages of nodes booting from a local area netwo ...
and
SNMP Simple Network Management Protocol (SNMP) is an Internet Standard protocol for collecting and organizing information about managed devices on IP networks and for modifying that information to change device behaviour. Devices that typically ...
). The main elements of an AFDX network are: * AFDX end systems * AFDX switches * AFDX links


Virtual links

The central feature of an AFDX network are its ''virtual links'' (VL). In one abstraction, it is possible to visualise the VLs as an
ARINC 429 ARINC 429, "Mark33 Digital Information Transfer System (DITS)," is also known as the Aeronautical Radio INC. (ARINC) technical standard for the predominant avionics data bus used on most higher-end commercial and transport aircraft. It defines the ...
style network each with one source and one or more destinations. Virtual links are unidirectional logic paths from the source end-system to all of the destination end-systems. Unlike that of a traditional Ethernet switch which switches frames based on the Ethernet destination or MAC address, AFDX routes packets using a virtual link ID, which is carried in the same position in an AFDX frame as the MAC destination address in an Ethernet frame. However, in the case of AFDX, this virtual link ID identifies the data carried rather than the physical destination. The virtual link ID is a 16-bit
unsigned integer In computer science, an integer is a datum of integral data type, a data type that represents some range of mathematical integers. Integral data types may be of different sizes and may or may not be allowed to contain negative values. Integers are ...
value that follows a constant 32-bit field. The switches are designed to route an incoming frame from one, and only one, end system to a predetermined set of end systems. There can be one or more receiving end systems connected within each virtual link. Each virtual link is allocated dedicated bandwidth MTU.html"_;"title="Maximum_Transmission_Unit.html"_;"title="um_of_all_VL_bandwidth_allocation_gap_(BAG)_rates_x_Maximum_Transmission_Unit">MTU">Maximum_Transmission_Unit.html"_;"title="um_of_all_VL_bandwidth_allocation_gap_(BAG)_rates_x_Maximum_Transmission_Unit">MTUwith_the_total_amount_of_bandwidth_defined_by_the_system_integrator._However,_total_bandwidth_cannot_exceed_the_maximum_available_bandwidth_on_the_network._Bi-directional_communications_must_therefore_require_the_specification_of_a_complementary_VL. Each_VL_is_frozen_in_specification_to_ensure_that_the_network_has_a_designed_maximum_traffic,_hence_determinism._Also_the_switch,_having_a_VL_configuration_table_loaded,_can_reject_any_erroneous_data_transmission_that_may_otherwise_swamp_other_branches_of_the_network._Additionally,_there_can_be_sub-virtual_links_(sub-VLs)_that_are_designed_to_carry_less_critical_data._Sub-virtual_links_are_assigned_to_a_particular_virtual_link._Data_are_read_in_a_Round-robin_scheduling.html" ;"title="Maximum_Transmission_Unit">MTU.html" ;"title="Maximum_Transmission_Unit.html" ;"title="um of all VL bandwidth allocation gap (BAG) rates x Maximum Transmission Unit">MTU">Maximum_Transmission_Unit.html" ;"title="um of all VL bandwidth allocation gap (BAG) rates x Maximum Transmission Unit">MTUwith the total amount of bandwidth defined by the system integrator. However, total bandwidth cannot exceed the maximum available bandwidth on the network. Bi-directional communications must therefore require the specification of a complementary VL. Each VL is frozen in specification to ensure that the network has a designed maximum traffic, hence determinism. Also the switch, having a VL configuration table loaded, can reject any erroneous data transmission that may otherwise swamp other branches of the network. Additionally, there can be sub-virtual links (sub-VLs) that are designed to carry less critical data. Sub-virtual links are assigned to a particular virtual link. Data are read in a Round-robin scheduling">round-robin sequence among the virtual links with data to transmit. Also sub-virtual links do not provide guaranteed bandwidth or latency due to the buffering, but AFDX specifies that latency is measured from the traffic regulator function anyway.


BAG rate

BAG stands for bandwidth allocation gap, this is one of the main features of the AFDX protocol. This is the maximum rate data can be sent, and it is guaranteed to be sent at that interval. When setting the BAG rate for each VL, care must be taken so there will be enough bandwidth for other VL's and the total speed cannot exceed 100 Mbit/s.


Switching of virtual links

Each switch has filtering, policing, and forwarding functions that should be able to process at least 4096 VLs. Therefore, in a network with multiple switches (cascaded star topology), the total number of virtual links is nearly limitless. There is no specified limit to the number of virtual links that can be handled by each end system, although this will be determined by the BAG rates and maximum frame size specified for each VL versus the Ethernet data rate. However, the number of sub-VLs that may be created in a single virtual link is limited to four. The switch must also be non-blocking at the data rates that are specified by the system integrator, and in practice this may mean that the switch shall have a switching capacity that is the sum of all of its physical ports. Since AFDX utilizes the Ethernet protocol at the MAC layer, it is possible to use high performance COTS switches with Layer 2 routing as AFDX switches for testing purposes as a cost-cutting measure. However, some features of a real AFDX switch may be missing, such as traffic policing and redundancy functions.


Usage

The AFDX bus is used in Airbus A380, Boeing 787, Airbus A400M,
Airbus A350 The Airbus A350 is a long-range, wide-body twin-engine jet airliner developed and produced by Airbus. The first A350 design proposed by Airbus in 2004, in response to the Boeing 787 Dreamliner, would have been a development of the A330 wi ...
,
Sukhoi Superjet 100 The Sukhoi Superjet 100 () or SSJ100 is a regional jet designed by Russian aircraft company Sukhoi Civil Aircraft, a division of the United Aircraft Corporation (now: Regional Aircraft – Branch of the Irkut Corporation). With development starti ...
,
ATR 42 The ATR 42 is a regional airliner produced by Franco-Italian manufacturer ATR, with final assembly in Toulouse, France. On 4 November 1981, the aircraft was launched with ATR, as a joint venture between French Aérospatiale (now Airbus) and ...
,
ATR 72 The ATR 72 is a twin-engine turboprop, short-haul regional airliner developed and produced in France and Italy by aircraft manufacturer ATR (french: Avions de transport régional or it, Aerei da Trasporto Regionale), a joint venture formed b ...
(-600),
AgustaWestland AW101 The AgustaWestland AW101 is a medium-lift helicopter in military and civil use. First flown in 1987, it was developed by a joint venture between Westland Helicopters in the United Kingdom and Agusta in Italy in response to national requirement ...
,
AgustaWestland AW189 The AgustaWestland AW189 is a twin-engined, super-medium-lift helicopter manufactured by Leonardo S.p.A. It is derived from the AW149, and shares similarities with the AW139 and AW169. Development On 20 June 2011, development of the eight-tonn ...
,
AgustaWestland AW169 The AgustaWestland AW169 is a twin-engine, 10-seat, 4.8t helicopter developed and manufactured by the helicopter division of Leonardo (formerly AgustaWestland, merged into Finmeccanica since 2016). It was designed to share similarities with the ...
,
Irkut MC-21 The Irkut MC-21 (russian: Иркут МС-21) is a single-aisle airliner, developed in Russia by the Yakovlev Design Bureau and produced by its parent Irkut, a branch of the United Aircraft Corporation (UAC), itself a 92%-owned subsidiary o ...
,
Bombardier Global Express The Bombardier Global Express is a large cabin, 6,000 nmi / 11,100 km range business jet designed and manufactured by Bombardier Aviation (formerly Bombardier Aerospace). Announced in October 1991, it first flew on 13 October 1996, receiv ...
,
Bombardier CSeries The Airbus A220 is a family of five-abreast narrow-body airliners by Airbus Canada Limited Partnership. It was originally designed by Bombardier and had two years in service as the Bombardier CSeries. The program was launched on 13 July 2 ...
,
Learjet 85 The Learjet 85 was a Learjet development program by aircraft manufacturer Bombardier Aerospace. The program was launched on October 30, 2007 and a mockup of the aircraft was unveiled in October 2008 at the NBAA show in Orlando. The Learjet 85 w ...
,
Comac ARJ21 The Comac ARJ21 Xiangfeng () is a 78–90 seat regional jet manufactured by the Chinese state-owned aerospace company Comac. Development of the ARJ21 (Advanced Regional Jet) began in March 2002, the first prototype was rolled out on 21 Decem ...
, Comac C919 and
AgustaWestland AW149 The AgustaWestland AW149 is a medium-lift multi-role military helicopter developed by AgustaWestland, now Leonardo, launched in 2006. On 20 June 2011 AgustaWestland announced the AW189, a civilian development of the AW149, for service in 2013. ...
.


References


External links


AFDX/ARINC664P7
AIM Avionics Databus Solutions, Interface Boards for AFDX/ARINC-664
PBA.pro-AFDX
AIM Avionics Databus Solutions, Analyzers for AFDX/ARINC-664 and more
AFDX Training
by AIM Avionics Databus Solutions, Interface Boards for AFDX/ARINC-664

by Mercury Instruments, Inc. ARINC664/AFDX Simulation and Verification Solution.
ARINC-664 part 7(AFDX) Tutorial (video)
from Excalibur Systems Inc.
Embvue AFDX , Arinc 664
by Embvue
AFDX/ARINC 664 Tutorial
from GE Intelligent Platforms

(EC Comp GmbH) *[https://web.archive.org/web/20150417191346/http://www.mhz-solutions.com/software/afdx/AEDX.html Avionics Ethernet Data Xplorer ARINC-664P7 Simulyzer - Software for monitoring, simulating and testing ARINC-664P7 / AFDX systems ] (MHZ Solutions)
AFDX SID data frame structure
(MHZ Solutions) {{Ethernet Industrial Ethernet Avionics