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ACP-SWGN110/WP-xx
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International Civil Aviation Organization
WORKING PAPER / ACP-SWGN1-10/WP-1011
13 Sep 2006

AERONAUTICAL COMMUNICATIONS PANEL (ACP)

10th MEETING OF SUB-WORKING GROUP N-1

Montreal, Canada 25-29 September 2006

Agenda Item 5.2: / Completion of the “Use of IPS for A-G Study”

STATUS OF EUROCONTROL STUDY INTO IPS FOR AIR-GROUND ATM COMMUNICATION

(Presented by Tony Kerr)

SUMMARY
The status of an ongoing study into the use of the Internet Protocol Suite (IPS) for air-ground data communication is presented.
ACTION
It is strongly recommended that the conclusions of the study should be taken into account in the SGN1 “Use of IPS for A-G Study.”

1.INTRODUCTION

1.1As previously reported to ACP WGN (WGN06-IP04), EUROCONTROL has commissioned a study into the use of the Internet Protocol Suite (IPS) for future air-ground communication supporting Air Traffic Services (ATS).

1.2This working paper provides an update of the current status of the Study, and recommends that the Study findings should be taken into account in the related work items being undertaken by WGN and its subgroups.

1.3SGN1 members are informed that an open workshop is planned for 8th November 2006 at EUROCONTROL Headquarters in Brussels to discuss Data Link Service requirements and IPS implementation options. The assessment criteria and the security report will be presented. Consensus will be sought as to the preferred mobility scenario.

2.discussion

2.1Purpose

2.1.1This working paper provides an update on a study being undertaken by a consortium of industrial partners on behalf of EUROCONTROL into the use of the Internet Protocol Suite (IPS) for future air-ground communication supporting critical Air Traffic Services (ATS).

2.1.2The study is being undertaken by a team which has wide experience both of the aviation and wider industrial applications of the IPS. It will explore the potential of a future system based on IPS solutions, taking account of lessons learnt from current ATN-based implementations.

2.1.3The international team is led by Helios Technology (UK), and supported by Luftfartsverket LFV (Sweden), Sofréavia (France), SITA (Multinational), Ericsson (Sweden), Rockwell Collins (France) and DLR (Germany).

2.2Overview of the Study Objectives

2.2.1The Future Communication Infrastructure (FCI) will support both ATS and AOC data communication applications between aircraft and ground systems for the year 2020 and beyond. The aims of the Study are to assess the feasibility of using IP to support the next generation of collaborative ATS applications. A key assessment criterion will be the ability to meet future requirements in a way that can take advantage of the wide availability of widely available commercial off-the-shelf (COTS) components.

2.2.2The study has started by identifying a representative sample of Data Link Services that will be deployed in the 2020+ timeframe. From consideration of these Data Link Services, a common set of application requirements is being derived, that an IPS implementation must satisfy if it is to be successfully deployed.

2.2.3In parallel, the use of the IPS over a representative sample of air-ground, ground-ground and air-air networks is being investigated. In particular, the study addresses the question “what is COTS?” when applied to the IPS. The requirement is to use widely accepted communications protocol standards that are implemented and used in real commercial products, and to avoid aviation–specific adaptations and “dead-end” experimental protocols, to the maximum extent possible.

2.2.4The result will be a set of “top down” application requirements and “bottom up” information on how the IPS is expected to be implemented and what it can provide.

2.3Mobility Support

2.3.1It is anticipated that there will be a gap between the “top down” and the “bottom up” requirements, corresponding to the support of mobility. Meeting the mobility requirements will be key to introduction of the IPS.

2.3.2The mobility issue will be addressed by identifying candidate mobility scenarios compatible with how the IPS might be expected to be implemented, and assessing them against the application and user requirements.

2.3.3Three candidate scenarios for meeting the mobility requirements have been identified so far. Two of these are “traditional” approaches, in which the end user does not need to be aware of mobility issues. The third is more radical and exposes applications to changes in network connectivity. The scenarios are:

a)A simple translation of the current ATN specification to the IPS. This would be very similar to the current ATN mobility support, but using the IPS protocol BGP-4 (RFC 1771 Border Gateway Protocol) instead of ISO standard IDRP (ISO/IEC 10747 Inter-domain Routing Protocol). The applications and ATN Upper Layer Communications Service are otherwise unchanged. If this scenario is to be successful then it will be important to demonstrate that the known problems can be solved without a radical change of approach.

b)An IPS ATN based on RFC specified Mobile IP. The study will investigate whether such scenarios result in a reduced level of functionality (e.g. by not supporting more than one mobile network simultaneously), and if so how significant this is. There is also a concern over COTS support of Mobile IP, and this issue will need investigation.

c)Application managed mobility. This is a “three layer approach”, where the lowest layer is standard TCP/IP with no special requirements including no mobility support requirements. The middle layer is an ATN message server and provides a common message exchange and mobility management. It encapsulates what is ATN specific functionality that is common to all Data Link Services, but which is not subject to safety requirements. The top layer is the user layer. This supports the user exchange of messages and is subject to safety requirements.

2.3.4The third scenario is being developed so that it could be deployed without the mobility extensions, i.e. the proposed architecture is that of an Application Message Server which can be extended to manage both multi-homing (for resilience) and IP Address changes (for mobility). It is thus also providing a common communications environment for all three solutions.

2.3.5Each of the above scenarios will be documented and analysed against an agreed set of evaluation criteria including the application requirements identified earlier, but also safety, performance, security, efficiency, coverage, cost and availability of COTS components. As a result of these analyses, a recommendation will be made on the appropriate mobility scenario for an IPS ATN and to identify any remaining issues.

2.4Security

2.4.1The study will address security issues by conducting a threat and vulnerability analysis for each of the above scenarios. Use of IPSec is expected to be integral to the design of the Application Message Server. The Key Management strategies are being investigated and Key Management may also be an integral part of the Message Server Architecture.

2.5Consultation and Dissemination

2.5.1In order to obtain a wide involvement from stakeholders when assessing the candidate scenarios, the focal point of the assessment will be a workshop, foreseen for 8th November 2006 at EUROCONTROL HQ. At the workshop, the Data Link Service requirements and IPS implementation options and the three candidate scenarios will be presented. The assessment criteria and the security report will also be presented. Consensus will be sought as to which is the preferred scenario.

2.5.2Once the recommended scenario has been agreed, a “helicopter view” of the resulting ATN will be provided and Use Cases will be documented. Trials and Simulations for validating the recommendations and resolving any identified issues will be proposed.

2.6The final study outputs will be reported at the ACP WGN and SGN1 meetings following the completion of the study.

2.7Deliverables and Timescales

2.7.1The study commenced in June 2006 and is planned to complete by the end of January 2007.

2.7.2The main deliverables from the study are summarised in the following table:

Deliverable Reference / Title / Approximate Date / Current Status
D1 / Application Requirements Analysis Report / Delivered / Internal review
D2 / IPS Analysis Report / Delivered / Internal review
D3 / Report on Assessment of Candidate FCIs / 01 Oct 2006
D4 / Security Report / 31 Oct 2006
D5 / Report on the Candidate IPS Architecture / 15 Dec 2006
D6 / Final Report / 30 Jan 2007

3.ACTION BY THE MEETING

3.1The ACP SGN1 is invited to:

  • Note the progress being made on the EUROCONTROL Study into IPS for Air-Ground ATM Communications
  • Comment on the scope and approach of the study
  • Note that an open workshop is planned for 8th November 2006 to discuss Data Link Service requirements and IPS implementation options, and attempt to build consensus as to the way forward.
  • Note that the final report of the Study is scheduled for 30 January 2007
  • Plan to incorporate the conclusions of the Study into the appropriate work item of the sub-working group before presenting any conclusions to ACP WGN.

APPENDIX A.WORK ITEM SUMMARY

This Appendix provides additional information on the work items being performed. The Study is organised into the 7 work packages outlined below.

WP1: Application Requirement Analysis

This work package aims to provide a firm basis for the subsequent work packages, by providing a consistent and up-to-date set of application requirements and a revised set of ATN communication requirements. The work package comprises the following tasks:

1.Documentation of the LINK 2000+ Data Link Services requirements;

2.Identification of the CASCADE Data Link Services requirements, including broadcast applications and ASAS;

3.Identification of Oceanic Data Link Service Requirements including FANS-1/A convergence;

4.Identification of additional Data Link Services for deployment up to and including 2020 and their requirements;

5.Documentation of existing AOC Applications;

6.Identification of future AOC Applications in the 2020+ timeframe;

7.Review and validation of the ATN Communication Requirements, including how the data exchanges of Data Link Services should be specified.

For each individual Data Link Service, the Safety Requirements and the Required Communications Performance (RCP) are identified. The RCP includes:

•Data Integrity;

•Availability (AUSE and APROVISION);

•Elapsed Time (ET) and Transit Time for the 95th percentile (TT(95));

•Communications reliability (probability of message delivery within a defined time).

In addition, mobility and security requirements are being identified.

WP2: IPS Analysis

This work package considers the use of the IPS in the air-air, air-ground, and ground-ground environments. Maximum commonality between the environments is a desirable objective; hence the desire to consider the three environments together. The main objective of this work package is to identify how the IPS will be used over each subnetwork and the approaches available to meet user security requirements. The work takes into account the current work of ICAO ACP SGN1 and SGN4 on the use of the IPS for Aeronautical Communication, but will not consider mobility issues, as this is left to WP3.

The aim of the work package is to gather together the state of knowledge for the use of IPS in order to inform the analysis carried out in WP3.

The work package comprises the following tasks:

1.Analysis of “What is COTS?” This task comprises a survey of IPS protocols, specifications and products, in order to identify not just those that are relevant to these environments but also which are available as robust products. Availability in standard Linux distributions will be an important consideration of what is COTS. Input will also be taken from the recent EUROCONTROL study into Migration to IPv6 for ATM air-ground data communication.

2.Use of the IPS in VDL Mode 2: This task documents current and future plans for the possible use of the IPS in a VDL Mode 2 context and aims at determining the most likely implementation architecture, and implementation issues.

3.Use of the IPS in VDL Mode 4: This task documents current and future plans for the possible use of the IPS in a VDL Mode 4 context and aims at determining the most likely implementation architecture and implementation issues. It includes consideration of XDL4 (VDL4 in another RF band).

4.Use of the IPS in Satellite Communications: This task documents current and future plans for the possible use of the IPS in a SATCOM context, including services such as Inmarsat SwiftBroadband, and aims at determining the most likely implementation architecture and implementation issues.

5.Use of the IPS in Terrestrial Wideband: This task documents current and future plans for the possible use of the IPS in a Terrestrial Wideband context such as that developed for EUROCONTROL’s Wideband Trials project, and aims at determining the most likely implementation architecture and implementation issues.

6.Use of the IPS in Aeronautical Ground Networks: This task documents current and future plans for the possible use of the IPS in a ground/ground context and aims at determining the most likely implementation architecture and implementation issues. Input material will be taken from the iPAX task force and the Pan-European Network Service (PENS) Project.

7.Use of the IPS in the passenger cabin and onboard aircraft. This task will review the ARINC 664 (ADN) outputs and identify the likely availability of on board IPS communications networks.

8.Use of Public Safety and specialised Mobile Radio Networks. This task will document the use of the IPS over example Public Safety and specialised Mobile Radio Networks. It includes consideration of P34.

9.Air-Air use of the IPS. This task will document the possible use of the IPS for support of Air-Air Data Link Services including but not necessarily limited to ASAS.

10.IP security, including IPSec and SSL.

WP3: Assessment of Candidate Future Comm Infrastructures

This WP is to identify and make recommendations on the appropriate Mobility Scenario. Each architecture will be defined and assessed under this work package, against a number of well-defined assessment criteria, to be derived during the study.

The work package comprises the following tasks:

1.Finalisation of scenarios and assessment criteria. The criteria will be reviewed and an agreed assessment plan developed.

2.Description of the Application Message Server architecture.

3.Development of an outline description of the architecture for Mobility Management using Standard Routing Protocols (Scenario 1).

4.Development of an outline description of the architecture for Mobility Management using Mobile IP to manage mobility (Scenario 2).

5.Development of an outline description of the architecture for Mobility Management using the Application Message Server (Scenario 3).

6.Assessment of the candidate architectures. The assessment will be conducted according to the agreed assessment criteria.

7.Documentation of the results of the assessment.

WP4: Security Threat and Vulnerability Analysis

A threat and vulnerability analysis will be conducted for the Data Link Services identified in WP1 and implemented under each of the three candidate architectures described in WP3. In this context, and for ATS Applications, the threats are defined as “deliberate acts that result in a failure to meet Safety Objectives corresponding to remote or more serious hazards”. Essentially, these are threats that could result in a loss of aircraft separation.

The work package comprises the following tasks:

1.Threat and Vulnerability analysis workshop.

2.Security Analysis of the common parts of the Architecture.

3.Security Analysis of the Scenario 1 Candidate IPS Architecture.

4.Security Analysis of the Scenario 2 Candidate IPS Architecture.

5.Security Analysis of the Scenario 3 Candidate IPS Architecture.

WP5: Review and Recommendation of the Candidate IPS Architecture

After reviewing the outputs of WP3 and WP4, this WP is to develop recommendations on the FCI architecture. The following tasks are included:

1.Review of WP3 and WP4 outputs, leading to a recommendation on the most appropriate FCI architecture. This task will be performed as a workshop.

2.Documentation of Workshop conclusion.

3.ATN to IPS Transition Approach. Develop a proposal for mixed mode operations during a transition phase from the current ATN to an IPS based ATN. It will also describe how components of the FCI (VHF data link, satellite solutions, current airborne architecture, ground infrastructure, etc.) will migrate to the envisioned FCI architecture. Issues concerning migrating existing data link applications, both ATN and FANS-1/A, to the FCI will also be considered.

4.A "helicopter view" of the FCI will be documented. It will take an end-to-end approach of the communications chain between flight data processing systems (including controller HMI as well as automated functions) on the ground, and aircraft systems (including flight management automation and cockpit HMIs).

WP6: Use Cases

This WP is to develop use cases describing the progress of a typical commercial passenger flight from departure gate to arrival gate in terms of the transitions seen at the data communications infrastructure level. They will show how the proposed mobility solution maintains the required level of communications services, continually satisfying interoperability, safety, and performance requirements, through all phases of flight.

1.Use Case demonstrating a set of ATC services.

2.Use Case demonstrating use of ASAS.

3.Use Case demonstrating use of AOC Applications.

WP7: Trials and Simulations

Proposals will be made for the development of prototype systems and trials, where required, to demonstrate the feasibility of the recommendations. The trials are to provide a validation of the principles and investigation of any outstanding issues identified in WP5.