CNCL NO S/S

This standard details the functionality and principle interfaces for the ASAAC (Allied Standard Avionics Architecture Council) Network to ensure the interoperability of Common Functional Modules and design guidelines to assist in implementation of such a network. It is one of a set of standards that define an ASAAC Integrated Modular Avionics (IMA) System.

The purpose of this standard is to establish by means of well defined interfaces and functionality, a network design that is technology transparent, that is open to a multi-vendor market and that can make the best use of Commercial Off The Shelf (COTS) technologies. Therefore, the associated data communication network topology, protocols and technologies are not identified in this document. For these items the document identifies the issues that should be considered when defining a specific network implementation to support the ASAAC architecture and provides guidelines to assist.

Although the physical organisation and implementation of the network shall remain the System Designers choice, in accordance with the best use of the current technology, it is necessary to define interfaces and parameter sets in order to achieve a logical definition of the network with a defined functionality. This definition includes:

The generic functionality applicable to all networks.

The logical interfaces to the Operating System and Module Support Layers.

The physical interfaces to the Common Functional Modules (CFM).

The ASAAC Standards are intended to be independent of specific technologies, including network technologies. This document identifies the principle interfaces for the Network, in section 5, and where appropriate, provides requirements on network parameters to be defined. The interfaces relevant to the network are the Module Support Layer to Operating System (MOS), Module Physical Interface (MPI) and Module Logical Interface (MLI). The MOS and MPI are generically defined elsewhere (Standards for Software [2] and Packaging [4]). The MLI is clearly a function of the selected network. The MOS and MPI definitions are generic and will need to be supported by network specific information. There is no networkdependent information in the Software or Packaging standards. So a future network specification will not only define the particular MLI, but will also need to define the specific aspects of the MPI, topologies, system properties etc.

Relationship with other ASAAC Standards

The definition of the complete Communications and Network Interfaces is partitioned and is covered by the following ASAAC standards:

Network physical Interfaces – ASAAC Standards for Packaging.

Module to Module Communication functions – ASAAC Standards for Software.

Operating System to Network interface – ASAAC Standards for Software.

CFM Software Architecture – ASAAC Standards for Software.

Network physical requirements and properties that define the capability and behaviour required to support CFM to CFM communications – This document.