This whitepaper looks at Integrated versus Component Management of AFTN and AMHS Systems for Aviation messaging. It looks at the differences between these approaches and the benefits of each. A summary is given of the Isode product capabilities to support integrated management, and integrated AMHS & AFTN Management (in the shape of the AIDA-NG product from Isode partner Comsoft) is described.
AMHS & AFTN
The aviation industry is adopting AMHS (Air Traffic Services (ATS) Message Handling Services) to support ground to ground communications for services such as flight plans and meteorological data. This will eventually replace the older AFTN (Aeronautical Fixed Telecommunication Network) based systems. The AMHS standards are specified by ICAO (International Civil Aviation Authority), based on X.400.
To enable co-existence of AMHS and AFTN, ICAO has also specified standards for interoperability between AMHS and AFTN, using a component formally referred to as an MTCU (Message Transfer & Conversion Unit) which provides a gateway between AMHS and AFTN.
Isode provides a complete AMHS server infrastructure using its M-Switch X.400 (Message Transfer Agent) and M-Store X.400 (Message Store) server products, described in more detail here. Isode provides protocols and APIs for integration of AMHS Client applications, and an AMHS Gateway API, that enables Isode partners to build MTCUs that are closely integrated with M-Switch X.400.
Integrated vs Component Management
In an environment moving from use of AFTN to use of AMHS, there will be a need for AFTN Servers, AMHS Servers, and MTCUs (at least one of each). There are two basic management architectures.
The diagram above illustrates component management, where AFTN, AMHS and MTCU have separate management.
Benefits of Component Management
Managing the component separately has the following advantages:
- Existing component management can be used out of the box. In particular, Isode management tools can be used for AMHS management. This reduces system development cost.
- Management tools can be specific to purpose, so that the tool for managing a specific component is tailored for that single function.
Benefits of Integrated Management
An integrated management approach gives a number of advantages:
- Single view for operator of multiple systems, so that all components can be managed as a single system. This means in particular unified queue handling, configuration, and alarming as well as common administration procedures.
- One common traffic database for AMHS and AFTN therefore simplified tracing of message flow through the overall system including AMHS and AFTN networks.
- Common lower-layer protocol implementation and physical interfaces for AMHS and AFTN give flexibility to migrate gradually from AFTN to AMHS.
- Reduced cost for operator training and re-training.
Integrated versus component management has been presented above with the "extreme" positions. Intermediate combinations are possible, for example to use SNMP monitoring of all components from a single management station, but use separate management for control functions.
There will be many factors in choice of an AMHS and AFTN solution. An important one affecting management choice will be the nature of transition. Two scenarios are noted.
- "Slow Transition". Here a long period is anticipated when both AFTN and AMHS systems will both be operated, with some users receiving messages by AFTN and others by AMHS. Supporting this type of transition, an integrated management solution is ideal, because of the need to support a mix of users and to gradually change.
- "Fast Transition". Here, a rapid transition is made with all users moving at the same time from AFTN to AMHS. This means that local support for both AFTN and AMHS is needed for only a short transitional period. An MTCU will be needed for a longer period to support international connections not using AMHS. In this scenario, the component management approach may be preferable.
How Isode Supports Integrated Management
Isode provides M-Switch X.400 (X.400 Message Transfer Agent) and M-Store X.400 (X.400 Message Store) that provide full AMHS Server functionality (Basic and Extended Service). Isode provides a complete set of management tools for these that provide everything that is needed for the AMHS Server part of a component management approach. An MTCU based on M-Switch X.400 is tightly integrated, so Isode management also covers X.400 side of the MTCU and overall MTCU process management. Thus, component management of the Isode servers comes as a part of the Isode product.
Isode's strategy to support integrated management, is to ensure that all management GUIs are decoupled from the Isode servers, using a client/server architecture. This is described in detail in the Isode white paper Isode Management Architecture: Client/Server and Directory. This approach enables Isode partners to build management GUIs over the Isode infrastructure. The key elements of this are:
- Directory Schema, used to specify configuration of the Isode products.
- Use of Isode protocols, with documented APIs for messaging control functionality.
This architecture provides the Isode management functionality in a GUI-neutral manner, that enables managing the Isode products with different GUIs. This is a flexible approach, which can be used to provide custom access to specific pieces of functionality or to build a complete alternate GUI management system.
Although Isode's X.400 products form an excellent basis for the development of an AMHS solution with integrated management, the technical understanding and engineering efforts to achieve this is non-trivial.
Implementing AMHS systems adapted to the operational needs for the Air Traffic Control market is a complex task. In particular, the integrated management with unified handling of both AFTN and AMHS networks is often an explicit or implicit requirement of traffic operators. Isode's partner COMSOFT in close cooperation with Eurocontrol and leading national Air Navigation Services Provides chose the fully integrated approach to address their operational needs. This solution is shown in more detail in the next section.
Integrated Management in Comsoft AIDA-NG
COMSOFT's AIDA-NG product provides AMHS, AFTN and MTCU capabilities based on Isode’s M-Switch X.400 server. M-Switch is closely integrated with the AFTN application and the MTCU. Traffic and event logs as well as configuration data are stored in the same database which allows the operator to analyse these data within the context of the full system. Lower-layer protocols and interfaces are shared between the messaging applications of the various network parts.
M-Switch is fully integrated in COMSOFT's failover cluster technology with extremely fast switchover times. It provides an integrated management approach using COMSOFTs GUI over the Isode infrastructure. AIDA-NG is based on substantial operational experience, with numerous operational deployments using AMHS and AFTN the largest systems amongst them being installed in the United Kingdom, Germany, Singapore, Australia, and at Eurocontrol.
This paper has contrasted the Integrated and Component approaches to management of AFTN/AMHS systems, and the benefits of each. An integrated management system is particularly important where a slow transition is planned. The ability of the Isode products to support integrated management has been explained, and demonstrated by the Comsoft AIDA-NG product.