Local Area Networks (LANs) in Aircraft - FTP Directory Listing - FAA

2.1 NOTIONAL NETWORKED AIRCRAFT ARCHITECTURE.
Networking aircraft with the NAS is symptomatic of larger societal changes that are arising from
the emergence of the worldwide Internet network of networks. The Internet has had a profound
impact upon many aspects of modern life. Many businesses have redefined their relationships
with other businesses, increasingly basing them upon Internet-oriented electronic commerce
technologies. The public has also embraced the Internet, as witnessed by the growing ubiquity
of Internet services such as the worldwide web, instant messaging, and electronic mail within
popular culture. Perhaps because of this, many aircraft manufacturers are planning to install
onboard networks enabling passenger access to the Internet. However, if an aircraft
manufacturer opts to have an onboard network that is available to both passengers and avionics
equipment (i.e., a shared LAN), aircraft safety and security concerns arise. As previously
mentioned in the introduction, parallel, evolutionary changes to the NAS increasingly are being
proposed that rely upon greater integration between air-based and ground-based airspace
systems. For example, the operational integration of aircraft with the NAS’ communication and
logistics infrastructure promises dramatic improvements in operational efficiency. Thus, a
variety of motivations are increasing the connectivity of aircraft systems to air-based and
ground-based network infrastructures.
Current commercial aircraft systems and networks can be grouped in three major categories:
closed, private, and public. The closed networks are representative of safety-critical avionics
systems; private systems represent airline operational systems, cabin management systems, etc;
open systems are represented by public Internet services offered to passengers.
Several changes have been proposed for next generation of aircraft due to the use of local area
networking technologies. In response to these proposed changes, some projects have been
initiated in which the common onboard network is designed with partitioning protections. The
assured robustness of the proposed partitioning is a concern, from both a security and safety
perspective. Previous avionics systems have had their own data bus and have not been
accessible by nonavionics systems. Security has historically been enforced by a total lack of
access (i.e., an air gap) between systems. However, as this paradigm changes to support
common networked systems, the safety and security aspects of the onboard network must be
addressed by identifying the resulting risks and establishing appropriate controls to mitigate
those risks.
Several notional views of the current and future aircraft networked systems have been
formulated. Figure 1 shows one of those views. In figure 1, the current (existing) architecture is
shown on the left side, a logical picture of the proposed target architecture is in the middle, and a
list of changes to achieve the target (future) architecture is enumerated on the right. As
previously mentioned, a key feature of the existing architecture is its air gap between airborne
functions and passenger Internet services. Thus, there is no way a passenger or entities within
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