Subject: Re: [Gen-art] re-review of draft-ietf-mipshop-pfmipv6-11.txt

From: Hidetoshi Yokota <[email-masked]>
Date: Fri, 04 Dec 2009 13:22:44 +0900

Hello Francis,

Now I see what gave you a pain... A series of unfamiliar abbreviations
may hamper readability. Please take a look at the following style. The
key words below are spelled out:

MN -> mobile node
P/N-AN -> previous/new access network
P/NMAG-> previous/new MAG
etc.

If the revised style is acceptable, we will revise the whole document as
such.

============ <excerpt from Section 4.1> =======================
   (a)  The mobile node detects that a handover is imminent and reports
        the identifier of itself (MN ID) and the New Access Point
        Identifier (New AP ID) [RFC5568] to which the mobile node is
        most likely to move.  The MN ID could be the NAI or a Link Layer
        Address (LLA), or any other suitable identifier.  This step is
        access technology specific.  In some cases, the previous access
        network (P-AN) will determine which AP ID the mobile node is
        moving to.

   (b)  The previous access network, to which the mobile node is
        currently attached, indicates the handover of the mobile node to
        the previous mobile access gateway (PMAG).  Detailed definition
        and specification of this message are outside the scope of this
        document.

   (c)  The previous MAG sends the Handover Initiate (HI) message to the
        new mobile access gateway (NMAG).  The HI message MUST have the
        P flag set and include the MN ID, the HNP(s) and the address of
        the local mobility anchor (LMA) that is currently serving the
        mobile node.  If there is a valid (non-zero) MN Link-layer
        Identifier (MN LL-ID), that information MUST also be included.
        With some link layers, the MN Link-local Address IID (MN LLA-
        IID) can also be included (see Section 6.2.3).

   (d)  The new MAG sends the Handover Acknowledge (HAck) message back
        to the previous MAG with the P flag set.

   (e)  If it is preferred that the timing of buffering or forwarding
        should be later than step (c), the new MAG may optionally
        request the previous MAG at a later and appropriate time to
        buffer or forward packets by setting U flag [RFC5568] or F flag
        in the HI message, respectively.

   (f)  If the F flag is set in the previous step, a bi-directional
        tunnel is established between the previous MAG and new MAG and
        packets destined for the mobile node are forwarded from the
        previous MAG to the new MAG over this tunnel.  After
        decapsulation, those packets may be buffered at the new MAG.  If
        the connection between the new access network and new MAG has
        already been established, those packets may be forwarded towards
        the new access network, which then becomes responsible for them
        (e.g., buffering or delivering depending on the condition of the
        mobile node's attachment); this is access technology specific.

   (g)  The mobile node undergoes handover to the new access network.

   (h)  The mobile node establishes a physical link connection with the
        new access network (e.g., radio channel assignment), which in
        turn triggers the establishment of a link-layer connection
        between the new access network and new MAG if not yet
        established.  An IP layer connection setup may be performed at
        this time (e.g., PPP IPv6CP) or at a later time (e.g., stateful
        or stateless auto address configuration).  This step can be a
        substitute for the Unsolicited Neighbor Advertisement (UNA) in
        [RFC5568].  If the new MAG acquires a valid new MN LL-ID via the
        new access network and a valid old MN LL-ID from the previous
        MAG at step (c), these IDs SHOULD be compared to determine
        whether the same interface is used before and after handover.
        When the connection between the mobile node and new MAG is PPP
        and the same interface is used for the handover, the new MAG
        SHOULD confirm that the same interface identifier is used for
        the mobile node's link-local address (this is transferred from
        previous MAG using the MN LLA-IID option at step (c), and sent
        to the mobile node during the Configure-Request/Ack exchange).

   (i)  The new MAG starts to forward packets destined for the mobile
        node via the new access network.

   (j)  The uplink packets from the mobile node are sent to the new MAG
        via the new access network and the new MAG forwards them to the
        previous MAG.  The previous MAG then sends the packets to the
        LMA that is currently serving the mobile node.

   (k)  The new MAG sends the Proxy Binding Update (PBU) to the LMA,
        whose address is provided in (c).  Steps (k) and (l) are not
        part of the fast handover procedure, but shown for reference.

   (l)  The LMA sends back the Proxy Binding Acknowledgment (PBA) to the
        new MAG.  From this time on, the packets to/from the mobile node
        go through the new MAG instead of the previous MAG.
============

Regards,
-- 
Hidetoshi

Francis Dupont wrote:
> I have been selected as the General Area Review Team (Gen-ART) 
> reviewer for this draft (for background on Gen-ART, please see 
> http://www.alvestrand.no/ietf/gen/art/gen-art-FAQ.html). 
> 
> Please resolve these comments along with any other Last Call comments 
> you may receive. 
> 
> Document: draft-ietf-mipshop-pfmipv6-11.txt
> Reviewer: Francis Dupont
> Review Date: 2009-09-22/2009-11-30
> IETF LC End Date: 2009-09-22
> IESG Telechat date: unknown
> 
> Summary: Ready
> 
> Comments: the style is still at least questionable, I quote an example:
> 
>    (f)  If the F flag is set in the previous step, a bi-directional
>         tunnel is established between the PMAG and NMAG and packets
>         destined for the MN are forwarded from the PMAG to the NMAG over
>         this tunnel.  After decapsulation, those packets may be buffered
>         at the NMAG.  If the connection between the N-AN and NMAG has
>         already been established, those packets may be forwarded towards
>         the N-AN, which then becomes responsible for them (e.g.,
>         buffering or delivering depending on the condition of the MN's
>         attachment); this is access technology specific.
> 
> IMHO if abbrevs are fine in figures and can help to keep a document
> reasonably not too long, their abuse as in this document is clearly
> not a good thing. Now it is a matter of taste.
> 
> Regards
> 
> [email-masked]
> 
> 
>

---

From: Francis Dupont <[email-masked]>
Date: Fri, 11 Dec 2009 17:53:06 +0100

In your previous mail you wrote:

=> BTW I am familiar with most of these abbrevs (I worked a lot in Mobile
IPv6 area) but it is just a matter of taste: the abuse of abbrevs is
IMHO a bad style for a written text. And this includes the "use English
words the first time, introduce abbrevs and use them in place of plain
English after".
Please note it is a matter of taste and I am not against the use of
abbrevs, just against the abuse.

Regards

PS: I apologize for the delay (travel, mail server crash, ...)

---

From: Jari Arkko <[email-masked]>
Date: Mon, 14 Dec 2009 07:53:11 +0200

Francis,

> words the first time, introduce abbrevs and use them in place of plain

I agree, by the way. We can, of course, WR (Write) TXT (Text) with ABs 
(Abbreviations) but it just produces HTRT (Hard To Read Text). Its so 
much easier to just say "the mobile node" or "the home agent" than use 
one of the abbreviations.

(And I'm not demanding this conversion be done for the current document. 
But I find many of the documents that I see a little overusing the 
abbreviations.)

Jari

---

From: Hidetoshi Yokota <[email-masked]>
Date: Mon, 28 Dec 2009 23:08:10 +0900

Hi Jari and Francis,

I understand that some abbreviations familiar to me are not necessarily
so to others. In the latest document (v12), MN and LMA are spelled out
as "mobile node" and "local mobility anchor" as many as possible. Also,
the itemized descriptions for Figures 2 and 3 in Section 4.1 use more
unabbreviated words.

Apologize for this delay, but the latest version was submitted earlier
as v12. Hope that the readability has improved even a bit...

Regards,
-- 
Hidetoshi