Subject: Re: [RTG-DIR] RtgDir Last Call review: draft-ietf-raw-ldacs

From: "Dr. Corinna Schmitt" <[email-masked]>
Date: Fri, 22 Oct 2021 11:43:01 +0200

Dear All,

thanks for the feedback. We addressed it and uploaded a new version a
minute ago: https://www.ietf.org/archive/id/draft-ietf-raw-ldacs-09.html

In order to identify the parts where we addressed the received feedback
find it below in -line.

Regards,

Nils, Thomas, and Corinna

> ------------------------------------------------------------------------
> *Von:* Tal Mizrahi <[email-masked]>
> *Gesendet:* Mittwoch, 1. September 2021 12:11:59
> *An:* [email-masked]; [email-masked]
> *Cc:* [email-masked]; [email-masked]; [email-masked]
> *Betreff:* RtgDir Last Call review: draft-ietf-raw-ldacs
>  
>
> Hello,
>
> I have been selected as the Routing Directorate reviewer for this
> draft. The Routing Directorate seeks to review all routing or
> routing-related drafts as they pass through IETF last call and IESG
> review, and sometimes on special request. The purpose of the review is
> to provide assistance to the Routing ADs. For more information about
> the Routing Directorate, please
> see http://trac.tools.ietf.org/area/rtg/trac/wiki/RtgDir
> <http://trac.tools.ietf.org/area/rtg/trac/wiki/RtgDir>
>
> Although these comments are primarily for the use of the Routing ADs,
> it would be helpful if you could consider them along with any other
> IETF Last Call comments that you receive, and strive to resolve them
> through discussion or by updating the draft.
>
> Document: draft-ietf-raw-ldacs-08
> Reviewer: Tal Mizrahi
> Review Date: 2021-09-01
> Intended Status: Informational
>
> *Summary:*
> I have some minor concerns about this document that I think should be
> resolved before publication.
>
> *Comments:*
>
> The draft provides an overview of the L-band Digital Aeronautical
> Communications System (LDACS), which is a work-in-progress standard by
> the ICAO standardization group. The draft is well-written, and is
> almost ready for publication, with a few comments that follow.
>
> *Major Issues:*
>
>   * Although the abstract clearly explains that LDACS includes support
>     for IPv6, the reader later learns that LDACs is mostly a Layer 2
>     technology, and that IPv6 over LDACS has not been defined yet. The
>     document does not describe the connection between LDACS and IPv6,
>     why IPv6 was chosen (and not IPv4), and the challenges of using
>     IPv6 over this technology. It would be worthwhile to add a
>     paragraph or two about this to the introduction.
>
      o We mentioned further regulatory document such as ICAO Doc 9896,
        RTCA DO-379, EUROCAE ED-262 and ARINC P858 all concerned with
        the foreseen ATN/IPS aeronautical communications backbone
        infrastructure in the introduction (Step (2) ...). IPv6 has been
        chosen as the basis for the ATN/IPS network and LDACS is a
        datalink access network technology from the view of ATN/IPS.
        This I highlighted also in the introduction.

>  *
>
>
>   * Specifically, it would be  useful to add a paragraph that explains
>     how LDACS is related to IETF protocols, and whether any work is
>     expected in the IETF in this context.
>
      o We added a paragraph at the end of the introduction, explaining
        the LDACS relevance in RAW and within the IETF.

> *Other Issues:*
>
>   * Minor issues are concerns about clarity or technical accuracy that
>     should be discussed and resolved before publication, but which
>     would normally be resolved between the authors and the reviewers.
>   * Please include all of the minor issues you have found. Give as
>     much context information as possible (e.g., section numbers,
>     paragraph counts).
>   * If you find no minor issues, please write: "No minor issues found."
>
> *Nits:*
>
> - It would be useful to mention in the introduction in which parts of
> the world LDACS is expected to be deployed, and whether any
> geographical restrictions are expected in the context of this technology.

·       We addressed that in the introduction (Step (1)... “Since
central Europe has been identified as the area of the world, that
suffers the most from increased saturation of the VHF band, the initial
roll-out of LDACS will likely start there, and continue to other
increasingly saturated zones as the east- and west-cost of the US and
parts of Asia [ICAO2018]”).

>
> - Throughout the document the word "shall" (lowercase) is used often.
> It is not clear whether this is because this text refers to the future
> tense, or whether because this is phrased as a requirement. I would
> suggest to replacethe word "shall" by a different word, or to explain
> at the beginning what it means in this document.

·       Apart from directly citing the security objectives in chapter
9.3. and from RTCA DO-350A document in the appendix A, we removed the
word “shall” throughout the document.

>
> - Abstract:
>   "High reliability and availability for IP connectivity over LDACS
> are therefore essential."
>   It would be useful to also mention security in this sentence.

·       This is addressed now in the abstract.

>
> - Introduction:
>   "efficient aircraft control and safe separation"
>   Please clarify what you mean by separation (perhaps separation
> between entertainment system traffic and aircraft control traffic?).

    We clarified that by clearly stating “aircraft separation”. This is
    a term is used and widely known in aeronautics for ”…vertical and
    horizontal separation standards to facilitate the safe navigation of
    aircraft in controlled airspace” [ICAO Doc 4444 – Chapter 5].

>
> - Introduction:
>   The following sentence is mentioned in Section 4. Maybe it would be
> useful in the introduction.
>   "LDACS standardization within the framework of the ICAO started in
>    December 2016.  The ICAO standardization group has produced an
>    initial Standards and Recommended Practices document [ICA2018]."

·       Thank you for the note, we moved it to the end of the introduction

>
> - Section 3:
>   The term "Business Communication" is used several times. It would be
> useful to define what this means.

·       We added a short explanatory sentence in chapter 3 for a clear
definition of the term.

>
> - Section 5:
>   The word "RECOMMENDS" (uppercase) is used here. This is not a
> standard RFC2119 key word. Please change it to lowercase.

·       We changed all appearances of that word to lowercase.

>
> - Section 5:
>   "Regulatory this is considered related to the safety and regularity"
>   Please consider rephrasing this sentence. It is not clear.

·       We altered the sentence in chapter 5.2.4. for better understanding.

>
> - Section 8:
>   "FL and RL boundaries are aligned in time"
>   Please mention what is the method used for synchronizing the time.

·       We clarified this now by adding a mention of LDACS
synchronization symbols in chapter 8.2. now.

>
> - Section 9:
>   Figure 2 presents the LDACS protocol stack, where IPv6 is
> illustrated above the SNP layer. It would be useful to have some text
> in Section 9.5 that explains how the SNP layer is connectedto the IPv6
> layer, and why IPv6 is used here (vs. IPv4).

·       We added a paragraph clarifying the issue in chapter 7.3.
(second paragraph).

>
> - Section 10:
>   "Reasons for Wireless Digital Aeronautical Communications"
>   This title does not really fit the section - please consider
> rephrasing it.

·       We changed it to “Security in Wireless Digital Aeronautical
Communications” and also changed the content of the section slightly to
fir the title. As we relocated some parts of the text to other sections
you can find this part now adressed within Section 9

> - Section 10.2:
>   Typo: LADACS ==> LDACS

·       We changed this unfortunate typo. Keep in mind Section 10 is now
section 9 due to relocation of text parts.

>
> - Section 11:
>   "Privacy Considerations"
>   The text in this section is not related to privacy. I would suggest
> removingthis section completely.

·       We removed this section.

>
> - Reference section:
>   Please review the "normative references" section. I would move all
> the references to "informative", unless you find that one of these is
> absolutely required as normative.

·       We changed the order of bibliography: Now only regulatory
documents or the ICAO specification of LDACS are stated as normative
reference, while the rest has been declared informative references.

>
> - Please remove [RFC2119], as it is not used in the document.

    We removed unused references.

-- 
******************************************************

PD Dr. rer. nat. habil. Corinna Schmitt
Head of Secure IoT

Research Institute CODE
Universität der Bundeswehr München

Werner-Heisenberg-Weg 39
85577 Neubiberg, Germany

Email: [email-masked]
https://www.unibw.de/code
https://www.corinna-schmitt.de