Afdx (Avionics Full Duplex Switched Ethernet) is a deterministic network based on standard Ethernet technology (IEEE 802.3), which is defined by part 7 of ARINC664 protocol.

AFDX network composition

AFDX communication bus is composed of terminal system, switch and physical link, which constitutes a star topology. The transmission path of AFDX network is static, which is realized by directly loading the network configuration table with high reliability.

1) end system: the end system is an important part of AFDX communication network, which ensures the safe and reliable data exchange between nodes in the network. The end system not only provides hardware interfaces, but also provides various software program interfaces for users to read, write and receive user data.

2) Switch: Switch is responsible for data forwarding in AFDX network and connecting all terminal systems. Switches can be cascaded with each other to expand switch ports, which is convenient for the construction of large-scale communication networks.

Virtual link technology

Virtual link technology is the core technology of AFDX bus, which establishes a logical one-way connection from the source terminal to one or more target terminals, effectively divides bandwidth resources, and realizes time-sharing multiplexing of actual bandwidth.

At the sender, traffic shaping technology is used to allocate resources for virtual links. The end system will set two parameters for each virtual link in advance, namely the bandwidth allocation gap (BAG, representing the minimum time interval between frames) and the maximum frame length (Lmax), so as to limit the maximum available bandwidth of each virtual link (maximum available bandwidth =Lmax/BAG) and ensure that each virtual link follows.