AFDX(Avionics Full DupleX Switched Ethernet)

AFDX - Overview

1.Advanced protocol system to interconnect Avionics subsystem

2.The standard is based on widely approved and adopted standards like Ethernet (IEEE 802.3) and IP/UDP (Internet Protocols)which are applied for sharing information anywhere on the aircraft

3.100 MBit switched Ethernet (wire).

4.Uses a special protocol to provide deterministic timing and redundancy management.

5.The main elements of an AFDX network are:
- AFDX End Systems
- AFDX Switches
- AFDX Links

Topology Description:

1.AFDX is a network than bus.

2.All connections are full duplex (100 MBits/sec).

3.Redundancy is achieved by duplication of the connections (wires) and the Switches.


Specifications of AFDX:

1.UDP/IP protocol including IP fragmentation/reassembly.

2.Virtual Links and Sub-Links.

3.Traffic shaping through bandwidth allocation gap (BAG.

4.Redundancy control.

5.AFDX addressing with multicast and unicast addresses.

6.Sampling and queuing ports for transmit and receive.

7.Autonomously scheduled transmissions.

8.Statistic counters.

Avionics Full-Duplex Switched Ethernet:
Avionics Full-Duplex Switched Ethernet (AFDX) is Part 7 of the ARINC 664 Specification which defines how Commercial Off-the-Shelf (COTS) networking technology will be used for future generation Aircraft Data Networks (ADN).
AFDX is an Airbus trademark, the equivalent Boeing product is known as CDN or Common Data Network.
AFDX defines a low-level network and protocol to communicate between avionics (referred to as End-System) devices in aircraft.
It is based on Ethernet, and like all full-duplex networks uses dedicated outgoing and incoming channels to allow full-speed transmission in both directions at the same time.
AFDX extends standard Ethernet to provide high data integrity and deterministic timing.
It specifies interoperable functional elements at the following OSI Reference Model layers:

Data Link (MAC and Virtual Link addressing concept);
Network (IP and ICMP);
Transport (UDP and optionally TCP)
Application (Network) (Sampling, Queuing, SAP, TFTP and SNMP).
The Physical layer is not defined as part of ARINC 664 Part 7 (AFDX) but can be any of the solutions defined in ARINC 664 Part 2, including:

10BASE-T to support traffic at 10Mbit/s;
100BASE-TX and 100BASE-FX to support traffic at 100 Mbit/s; and
provisions for growth to 1000 Mbit/s operations.