Avionics Full-Duplex Switched Ethernet (AFDX), also ARINC 664, is a data network, patented by international aircraft manufacturer Airbus,[1] for safety-critical applications that utilizes dedicated bandwidth while providing deterministic quality of service (QoS).
[2] The AFDX data network is based on Ethernet technology using commercial off-the-shelf (COTS) components.
A data word consists of 32 bits communicated over a twisted pair cable using the bipolar return-to-zero modulation.
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.
Building on the experience from the A380, the Airbus A350 also uses an AFDX network, with avionics and systems supplied by Rockwell Collins.
AFDX adopted concepts such as the token bucket from the telecom standards, Asynchronous Transfer Mode (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).
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.
[11] A highly intelligent switch, common to the AFDX network, is able to buffer transmission and reception packets.
AFDX extends standard Ethernet to provide high data integrity and deterministic timing.
Also the switch, having a VL configuration table loaded, can reject any erroneous data transmission that may otherwise swamp other branches of the network.
Therefore, in a network with multiple switches (cascaded star topology), the total number of virtual links is nearly limitless.