This specification defines Network and Transport layer provisions for data networks that are installed on commercial aircraft. The definitions are based on Internet Engineering Task Force (IETF) Internet protocol and service standards that have been published as Request for Comments (RFC). In some cases the protocols and services are tailored for use on board aircraft. The specification identifies two types of networks: First, Compliant Aircraft Data Network, which operates fully within the applicable Internet specifications. Second, Profiled Aircraft Data Network, in which one or more industry standard protocols have been extended to address the unique environment of aircraft installations. Within the specification, the functionality of Internet protocols and services are defined with the intent that interoperability of components connected to onboard data networks can be achieved without undue restrictions on the component designer.