ADXN Core
ADXN network is a network standard derived from IEEE 802.3 implementing determinism and redundancy and supporting IP and UDP protocols for network and transport layer, respectively.
ADXN is a packet-based network. Each packet is composed by a header and a payload; this structure is present in each layer, thus for each layer a packet is composed by a header and a payload, which is in turn the packet of the upper layer.
Physical Layer
In order to reduce the adoption impact in existing environments and technologies, the physical layer is the same as standard networks: this does not require the manufacturer to design new electronics, with all the subsequent certification and validation requirements, but to reuse existing and well-established network technologies, and in particular technologies compliant with IEEE802.3 standard.
Thus, the physical layer can be implemented either with copper wires, and in particular 4 or 8 wires twisted cables, or with optical fibers. It is also suggested, for endpoint manufacturers, to consider a design that is agnostic to the physical technologies, for example using SFP transducers.
However, at physical layer redundancy is required to be implemented through two separate networks.
Link layer
Link layer is where the ADXN standard most differs from IEEE802.3 and adhere to other avionic standards, such as A664p7: in fact, communication links are defined as Virtual Links, which are the virtual routes for traffic flows. Each VL is a unidirectional connection between an End-System’ partition and another.
In ADXN, a VL shall be defined through:
An ID – that can also be found in the destination MAC Address in the packet headers
One source
A tBAG – the minimum interval between the beginning of two consecutive packets in the VL
VL Type – allows the definition of unencrypted or encrypted links, of links that can talk with other deterministic networks, such as A664p7-based networks, of service messages specific of ADXN; of course, if the VL type is AXED only, it is not compatible with other standard’ endpoints.
Network layer
The network layer has been designed to comply with IPv4 standard while Transport Layer relies on UDP, so to allow applications to use standard and existing libraries and technologies and to be abstracted from the actual network.
This choice has been carried out considering both existing standards, so to increase the integrability of ADXN, and the development effort for third party manufacturers.
