4
One of the reasons that AFDX is such an attractive tech-
nology is that it is based upon Ethernet, a mature technol-
ogy that has been continually enhanced, ever since its
inception in 1972. In fact, the commercial investment and
advancements in Ethernet have been huge compared say,
to ARINC 429, MIL-STD-1553, and other specialized data-
communications technologies.
As shown in Figure 1, an AFDX system comprises the follow-
ing components:
Avionics Subsystem: The traditional Avionics Subsystems
on board an aircraft, such as the flight control com-
puter, global positioning system, tire pressure monitoring
system, etc. An Avionics Computer System provides a
computational environment for the Avionics Subsystems.
Each Avionics Computer System contains an embedded
End System that connects the Avionics Subsystems to an
AFDX Interconnect.
AFDX End System (End System): Provides an “interface”
between the Avionics Subsystems and the AFDX Intercon-
nect. Each Avionics Subsystem the End System interface
to guarantee a secure and reliable data interchange with
other Avionics Subsystems. This interface exports an ap-
plication program interface (API) to the various Avionics
Subsystems, enabling them to communicate with each
other through a simple message interface.
AFDX Interconnect: A full-duplex, switched Ethernet in-
terconnect. It generally consists of a network of switches
that forward Ethernet frames to their appropriate destina-
tions. This switched Ethernet technology is a departure
from the traditional ARINC 429 unidirectional, point-to-
point technology and the MIL-STD-1553 bus technology.
Chapter 1 Overview
The Antecedents
Moving information between avionics subsystems on board
an aircraft has never been more crucial, and it is here that
electronic data transfer is playing a greater role than ever
before. Since its entry into commercial airplane service on the
Airbus A320 in 1988, the all-electronic fly-by-wire system has
gained such popularity that it is becoming the only control
system used on new airliners.
But there are a host of other systems — inertial platforms,
communication systems, and the like — on aircraft, that
demand high-reliability, high-speed communications, as well.
Control systems and avionics in particular, rely on having
complete and up-to-date data delivered from source to re-
ceiver in a timely fashion. For safety-critical systems, reliable
real-time communications links are essential.
That is where AFDX comes in. Initiated by Airbus in the evolu-
tion of its A380 Aircraft, they coined the term, AFDX, for Avion-
ics Full-DupleX, switched Ethernet. AFDX brings a number of
improvements such as higher-speed data transfer — and with
regard to the host airframe — significantly less wiring, thereby
reducing wire runs and the attendant weight.
What is AFDX?
Avionics Full DupleX Switched Ethernet (AFDX) is a standard
that defines the electrical and protocol specifications (IEEE
802.3 and ARINC 664, Part 7) for the exchange of data be-
tween Avionics Subsystems. One thousand times faster than
its predecessor, ARINC 429, it builds upon the original AFDX
concepts introduced by Airbus.
Figure 1. AFDX Network
Controllers
Actuators
Sensors
Controllers
Actuators
Sensors
Gateway
Avionics Computer System
AFDX
Interconnect
End
System
Avionics
Subsystem
Avionics
Subsystem
End
System
End
System
Avionics Computer System
Avionics Computer System
Internet
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