ACP SGN1/10 WP1007

AERONAUTICAL COMMUNICATIONS PANEL(ACP)

Working Group N - NETWORKING

SUBGROUP N1 – Internet Communications Services

Montréal, Canada, 25th– 29th September 2006

(10th Meeting)

Working Paper 1007

Observationson the proposed Draft Manual for an IPS Communication Service for the ATN

Prepared by Mark A. Brown (Japan)

Presented by the sub-group chairman

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ACP SGN1/10 WP1007

1.Introduction

1.1.This working paper presents observations by the Japanese members of ACP Working Group N on the draft Internet Communications Service (ICS) SARPs being developed by SGN1.

2.Discussion

2.1.We have concerns over the selection of IPv6 as the network protocol for the IPS-based ATN ICS, regarding its technical maturity and availability of commercial off-the-shelf (COTS) equipment. The main driver for using IPS protocols in the ATN is to reap the benefits of a well-understood, mature, and widely-implemented technology, with interoperable COTS products being available from a number of vendors at reasonable cost. However, despite the IPv6 protocol specification itself now being over seven years old and despite heavy industry investment, the adoption of this protocol has been very slow. In addition, some of the standards for the control and routeing protocols (e.g.RFC-4271 BGP-4 January 2006, RFC-4443 ICMPv6 March 2006) and security-related protocols (e.g.RFC-4305, RFC-4306, RFC-4307) specified by the draft IPS SARPs appear to be very recent, and so have only had limited time for implementation by vendors and for use in the field. We therefore question whether IPv6 technologies are sufficiently mature for the aeronautical community to reap the benefits promised by using IPS in the first place.

2.2.The limited number of IPv4 addresses versus the number of hosts worldwide is often cited as the main justification for the adoption of IPv6 commercially. However, the ATN IPS internet is a closed network, and is not, and should not, be connected directly to the public Internet. Therefore, address planning can ignore IANA allocations and can be tailored to the needs of the aeronautical community. Consequently, address exhaustion should not be a problem given the much more limited number of ATN hosts, and should not be a justification for the selection of IPv6 over IPv4 in the ATN.

2.3.From studies presented at ACP WGN06, it appears that the use of IPS for air-ground aeronautical communication is feasible but a number of approaches to mobility are still being examined, with BGP-4 routeing being only one candidate. The ATN ground IPS internet communications service should be harmonised with a future air-ground ISP ICS. Therefore, it would seem prudent to wait until the solution for achieving mobility in the IPS ATN has been selected, before settling on BGP-4 as the routeing protocol for the ground ICS.

3.Recommendations

3.1.SGN1 should investigate the practical feasibility of using IPv6 and the proposed supporting protocols (BGP4+, IPsec protocols) in the IPS-based ATN ICS, considering the maturity of the standards and availability of interoperable, standards-compliant equipment from more than one vendor.

3.2.SGN1 should await the outcome of the IPS air-ground study before further developing SARPs for the ATN IPS ground network. An analysis should be made of the requirements on the ground ICS to support the proposed mobility solution, to ensure that the ground network infrastructure is able to support ICS air-ground communication.

4.Conclusions

4.1.The meeting is invited to review the observations in this working paper, and to consider the recommendations.

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