Draft Report of the second ACP/SG N3 meeting (Montréal, May 2004) ATNP/SGN3/2
ACP WGN03-WP07
ACP/WGN/SGN3-DR2-1a
25/05/2004
AERONAUTICAL COMMUNICATIONS PANEL(ACP)
Working Group N - NETWORKING
SUBGROUP N3 – GROUND-GROUND Applications
Draft Report of the second ACP/SG N3 meeting (Montréal, May 2004)
Presented by Jean-Marc Vacher
Table of contents
1 Agenda Item 1 : Approval of Agenda 3
2 Agenda Item 2 : Administrative Concerns 3
3 Agenda Item 3: ATS Message Handling Services 3
4 Joint SGN3 – SGN4 Session about ATN Directory considerations 5
5 Agenda Item 4: Inter-Centre Communications (ICC) over the ATN 7
6 Existing Aeronautical Fixed Service (AFTN/CIDIN) 7
7 Future SG N3 work 7
8 Any Other Business 8
9 ATTACHMENT A : List of participants 9
10 ATTACHMENT B : List of working papers presented at the meeting 10
11 ATTACHMENT C : Agenda of the meeting as approved by the subgroup 11
STNA/sgN3r2-1a.doc Page 11 25/05/2004
Version 0.1a (Draft)
Draft Report of the second ACP/SG N3 meeting (Montréal, May 2004) ATNP/SGN3/2
Introduction
0.1 The Ground-Ground Applications Subgroup (SG N3) of the ACP/WGN held its second meeting in Montreal, Canada, from May 19th to May 21st, 2004.
0.2 There were 6 persons participating in the meeting, the list of which is supplied in Attachment A. The meeting was chaired by Jean-Marc Vacher, Chairman of the subgroup.
0.3 There were 10 working papers proposed for the meeting, including 1 information paper, the list of which is given in Attachment B.
1 Agenda Item 1 : Approval of Agenda
1.1 WP/2-1, including the proposed Agenda, was presented by Jean-Marc Vacher. The agenda was approved by the meeting.
2 Agenda Item 2 : Administrative Concerns
Agenda Item 2.1: Approval of the report of the SGN3/1 meeting
2.1 The report of the 1st SGN3 meeting was reviewed and approved without comments.
Agenda Item 2.2: Co-ordination with WGN and other working groups or subgroups
2.2 Brian Cardwell verbally informed the meeting about the discussions and outcome of the AFSG/7 meeting held in Paris last April. Significant work had gone ahead in terms of AMHS deployment activities and interoperability trials, by two groups of 3 or 4 States/Organizations. A list of potential PDRs had been put together concerning ATSMHS as a result of one of these exercises, these were currently under scrutiny before submission by interoperability testing partners. Eurocontrol had progressed its work on AMHS profile. A task force had been set up in Europe under the aegis of EANPG, for handling the BUFR issue. The Task Force would be co-ordinating with ICAO Headquarters. This could have a potentially significant impact on AFS communications.
2.3 JMV noted that Directory matters were not included in the terms of reference of any subgroup. This was becoming an issue in view of the number of contributions presented about this subject in the current set of meetings. Brian Cardwell agreed that this should be reported to the WG. Because the Security subgroup (SGN4) was also interested in directory matters, a joint session between SGN3 and SGN4 with subject “ATN Directory considerations” would take place in the current set of meetings.
2.4 JMV informed the meeting about the new mailing lists that were in operation, hosted by the CENA server in France. An information paper would be submitted in WGN to provide explanations on how to subscribe and use the lists.
2.5 Jean-Marc Vacher said that the subjects discussed in the subgroup would be reported to WGN. Some topics might be subject to further discussions in the Working Group. The intent was to have detailed discussions in the subgroup and more "high level" discussions in the working group.
3 Agenda Item 3: ATS Message Handling Services
Agenda Item 3.1: Evolution of existing SARPs and GM documents on ATSMHS
WP/2-4
3.1 J.M. Vacher presented WP/2-4 (Transport of binary data messages in AMHS). The goal of this paper was to review the AMHS specification for transfer of binary data messages, in the light of the new requirement created by the World Meteorological Organization (WMO) decision to migrate to Binary Universal Form for the Representation of meteorological data (BUFR) for Coded Meteorological Messages. The paper examined a number of options to carry binary data in AMHS, and proposed the adoption of the MHS FTBP (file-transfer body part) for this purpose and its inclusion in Document 9705.
3.2 A discussion took place to well understand the impact of the change, in which the current SARPs requirement mandating to support “bilaterally-defined body-parts” (BBP) would be relaxed to become optional. The meeting agreed with the proposed adoption of FTBP.
3.3 The proposed amendment to Document 9705 was then examined by the meeting. A minor amendment was made to the proposed update and supported by the meeting. It was further agreed to submit these for endorsement to WGN with the subgroup's support.
3.4 Tadashi Mahara informed the meeting about another new requirement concerning the transfer of binary data but on air-ground data links, such a requirement stemming from the METLINK Panel. This was considered out of the scope of the subgroup but would be referred to SGN2 (air-ground applications).
WP/2-6
3.5 Robert Willmott presented WP/2-6 (Comments on ACP WGN02-WP14 – AMHS implementation profiles). The referred paper, presented in the Bangkok SGN3 and WGN meetings (November 2003), introduced an initial view of sub-setting rules for AMHS. The AMHS Implementation Profiles paper suggested that support for BBP (or FTBP as agreed earlier in the meeting) was dependent on the Directory and the IPM Heading Extensions functions. This paper re-examined the rationale for these dependencies, and suggested a simpler structuring. This paper also provided comments and suggestions on the structure and purpose of the Implementation Profiles document.
3.6 A thorough discussion took place about the initial paper and the comments paper, concerning particularly the goals of the paper. There was a consensus that the paper should define technical profiles that could serve as (part of) a procurement specification. The set of profiles should form a “catalog” or list of a limited number of AMHS Functional Group combinations, each of them technically and operationally coherent. PC Chan said that there should not be too many individual subsets in the list, to facilitate interoperability. This view was supported by the meeting. Each user community, e.g. States in a Region, but not exclusively, could then refer to one of the profiles as a common procurement baseline, depending upon its community (e.g. regional) requirements. The meeting agreed about these principles and about the need to further develop the AMHS profiles document on this basis.
3.7 The detailed recommendations of WP/2-6 were then examined one by one. The meeting agreed with the view expressed in the paper that the support of BBP (or FTBP) should be relieved from its IHE or DIR dependency. The modification of terminology as well as the definition of several Directory Functional Groups to better explain the functional role of the directory was agreed.
3.8 Finally the recommendation that the “Global Minimum Subset” become “Basic Service AMHS + BBP” was the subject of a long debate. Pramuk Rungrojaree noted that the recommendations 1 to allow the subset “Basic Service + BBP”, and 3 about the global minimum, were in contradiction with the Bangkok decision to have “Basic Service + DIR (Directory)” as a Global Minimum subset. Brian Cardwell said that there was no immediate requirement for DIR and that it should consequently not be part of a global minimum profile. Robert Willmott was concerned with the risk of classifying as mandating functions not useful for all users. He was also seeking consistency between the EUR-AMHS Profile that he was developing for Europe under the aegis of Eurocontrol, and the Global Minimum defined within WGN. Jean-Marc Vacher saw as an issue the fact of contradicting the Bangkok decision. A consensus could not be reached about the Global Minimum to be recommended, the choice being between “Basic Service + FTBP” and “Basic Service + DIR + FTBP”. It was agreed to report about this situation to WGN, highlighting the different opinions expressed and the non-technical implications of mandating a given “Global Minimum” procurement profile.
WP/2-9
3.9 Robert Willmott presented WP/2-9 (AMHS and ATN Directory Functional Groups), which was an information paper. The paper listed a set of AMHS and ATN Directory Functional Groups that may be useful in the context of profiling AMHS and Directory Systems. The paper included both Functional Groups defined in the ISO/IEC ISPs and AMHS specific Functional Groups, using the basis of the previously commented paper (ACP WGN02-WP14 – AMHS implementation profiles). The paper finally provided a refinement of potential Directory functionality subsets providing a group of “AMHS DIR Functional Groups”.
3.10 The meeting discussed the relevance to AMHS of the listed FGs, suggesting to remove a few of them, and to group together some others. Overall, this information paper was considered as a good basis to determine the Functional Groups that could be used to form the profiles discussed with WP/2-6.
Agenda Item 3.2: Guidance Material on AMHS implementation
WP/2-3
3.11 J.M. Vacher presented WP/2-3 (Publication and Maintenance of the ICAO Register of AMHS MDs). The paper was related to the information collected by the ICAO Secretariat from ICAO Member States and Organizations, with the goal of building the “ICAO Register of AMHS MDs and addressing information”. The goal of this paper was to propose a set of practices and procedures aimed at publication and maintenance of the Register by the ICAO Secretariat, in co-operation with States continuing to provide up-to-date information.
3.12 The meeting made the following comments about the paper: PC Chan noted that there would be an interaction with AMHS operations. Until now in AFTN, declarations of new circuits were made after a time sufficient to ensure that operation was successful. The present paper was suggesting anticipated declaration, this was a change in practices. It was agreed that the procedures going to be defined should include guidance for urgent (fall-back) changes, in case difficulties would be met at the moment of applying the Register changes. Tadashi Mahara suggested that information be distributed by ICAO in two phases, first using a physical media such as a CD, and then electronically using existing AFS messaging (AFTN/CIDIN or AMHS).
3.13 The meeting put a lot of emphasis on the need for security at all stages of the procedures, particularly if the ICAO web site would be used for this purpose. It was recommended to use encryption and secure SSL-type access, if the Register were to be posted on the ICAO web site.
3.14 The meeting agreed that with the comments above, the paper formed an appropriate basis for discussing with the ICAO Secretariat the way in which the Register could be maintained.
4 Joint SGN3 – SGN4 Session about ATN Directory considerations
Presentation of working papers and information papers
SGN4 – IP0204
4.1 Tom McParland presented SGN4 – IP0204 (ATN Directory Vision). This information paper contained an ATN Directory Service Vision from the perspective of a product supplier. The paper discussed using directory services primarily for AMHS support. It was of interest to the Security Subgroup since a directory may be used for distribution of ATN Certificates. The paper was presented as a courtesy paper. The meeting noted the information provided.
SGN3 – WP/2-7
4.2 Robert Willmott presented SGN3 – WP/2-7 (an LDAP Contribution). The paper was a follow-up to ACP WGN02-WP17 ‘Use of LDAP Directory in support of AMHS’, which proposed that LDAP should be investigated as a TCP/IP alternative to accessing the Directory for support of AMHS. This paper provided some initial input to that investigation based on limited market and technical research carried out by Eurocontrol. The paper concluded that to use an LDAP directory server would need re-coding of all ASN.1 of AMHS and ATN schema elements into BNF. This would be a complex task. The paper recommended to select appropriate Directory Access Protocols from a provided list, for access to an ATN X.500 Directory Server.
4.3 The paper served as an efficient basis to a discussion between the participants to both subgroup meetings about the benefits, but also difficulties related to LDAP. The meeting noted the information provided and agreed to take it into account when progressing its work on directory considerations.
SGN3 – WP/2-5
4.4 Jean-Marc Vacher presented SGN3 – WP/2-5 (Scenarios for use of LDAP Directory in support of AMHS). The paper was also a follow-up to ACP WGN02-WP17 ‘Use of LDAP Directory in support of AMHS’. The goal of this paper was to progress this analysis by the definition of scenarios for use of LDAP, thereby enabling to determine the benefits and limits of applicability of LDAP directory services in support of AMHS. The paper highlighted the same limits of LDAP as the WP/2-7. Three scenarios were analyzed, among which one consisting of the development of an LDAP ATN Directory. In view of the above difficulties, the paper recommended not to progress this scenario. However a LDAP-based minimal scenario for a “LDAP Directory in support of AMHS address conversion” was presented, for potential implementation by the ATSOs which are intending to deploy AMHS. The paper recommended to further study this scenario, with a status to be determined in terms of ICAO publication.
SGN3 – WP/2-8
4.5 Robert Willmott presented SGN3 – WP/2-8 (Orphaned Object Identifiers in Doc. 9705 SV VII). This paper identified a registration problem with the Object Identifiers allocated to Directory Schema Elements (Object Classes, Attribute Types and Attribute Syntaxes etc...) defined in Doc 9705 SV VII.
4.6 It was agreed that a PDR should be submitted to the AMSG to correct this defect. Robert Willmott volunteered to make this submission. Jean-Marc Vacher mentioned that other defects in Sub-Volume VII should be the subject of at least another PDR. This would be further discussed in the AMSG. Tom McParland also took the action to review certificate issues in Sub-Volume VII and raise a PDR if appropriate.
Conclusion of the joint session
4.7 Tom McParland summarized that the session had been the opportunity of a fruitful exchange of information on these subjects which were of interest, but relatively new to SGN4. It was agreed that both subgroups would keep themselves mutually informed of their future progress in this area. The meeting generally agreed about the benefit of having such joint sessions.