The Basics Of AFDX

Within the avionics industry, there are multiple specialized types of networks that are required to operate, coordinate and integrate all the different systems within the aircraft. One of those specialized networks is the AFDX or Avionics Full-Duplex Switched Ethernet.

The AFDX was originally designed and developed, and then later patented, by Airbus, which is a civil aircraft manufacturing company headquartered in Blagnac, France. The purpose of the system is to provide a data network for what are termed safety-critical applications requiring top quality of service (QoS), as well as dedicated bandwidth.

Use of Commercial Off-The-Shelf Components

The use of commercial off-the-shelf types of components, which means they are available in the common marketplace, sets AFDX systems apart from other specialized systems within the avionics industry.

Through using these parts, the system cost of development and production can be reduced, and there can also be a decrease in the time to production, the cost of repairs and other relevant factors.

With the AFDX system, even with the commercial off-the-shelf components, there is still a definition for these parts now and in the future systems, and this is provided in ARINC 664 Part 7.

The Primary Aspects

There are six important or primary aspects and features of the AFDX networks. These include that they are:

* Full duplex

* Redundant

* Deterministic

* High speed

* Switched

* Profiled

There are also several very important components of an AFDX data network. These include the end systems, the switches, and the links.

The links, which are called Virtual Links or VLs allow one end system to be connected with one, or multiple, end systems. This connection is unidirectional, and the switches are used to route a specific frame from one end system to the preset corresponding end system or end systems. There is only one source on each VL, but there can be multiple end system receiving the data.

The bandwidth along these VL is carefully designed to allow maximum traffic. To allow a bi-directional communication, there is a complimentary VL, which reverses the process, ensuring that data transfer rates are always maximized. It is also possible for the AFDX switches to route secondary or less critical information through what are known as sub-VLs to maintain the safety-critical system data rates.
The AFDX bus and data network are used on a range of different aircraft today. This includes the Learjet 85, Boeing 787 and the Airbus A380 to name just a few.

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