Subject: [RTG-DIR] RtgDir review: draft-ietf-netext-pmip-lr-08.txt

From: "Les Ginsberg (ginsberg)" <[email-masked]>
Date: Sun, 26 Feb 2012 23:28:56 -0800

(Resending w corrected draft address)

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. The purpose
of the review is to provide assistance to the Routing ADs. For more
information about the Routing Directorate, please see
http://www.ietf.org/iesg/directorate/routing.html

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-netext-pmip-lr-08
Reviewer: Les Ginsberg
Review Date: 26 February 2012
IETF LC End Date: ???
Intended Status: Standards Track

Summary:
I have some minor concerns about this document that I think should be
resolved before publication.

Comments:
This document is clearly written and easy to understand.
This is the first PMIP document I have reviewed, so I went back and read
some of the previous RFCs. Despite that it may mean that some of my
comments/questions are naive. Please indulge me.

Major Issues:
No major issues found.

Minor Issues:

Why are you not using the "MN-CN" terminology from RFC 6279? The fact
that you use "MN-MN" makes me think that you are only addressing cases
where both endpoints are MNs. Is this the case? If so, this should be
explicitly stated. If not, it would seem to be better to use the RFC
6279 terminology.

Section 5

I assume the lack of requirement for synchronization works because the
LMA will always forward packets regardless of whether it has sent an
LRI/received an LRA? This implies that MNs and MAGs may receive
duplicate packets at times - which presumably should be no problem. I am
wondering if it would be useful to discuss these points?

Similarly, in Section 6.1 it is assumed that LMAs always forward
inter-MN packets regardless of the state of LR?

Nits:
A number of acronyms are used without definition. For example, in
Section 4 page 7 "HNP" "BUL" "BCE" are all undefined. This does not
represent a complete list. Can you please scrub the document for all
such occurences?

---

From: "Les Ginsberg (ginsberg)" <[email-masked]>
Date: Wed, 29 Feb 2012 20:32:18 -0800

Suresh -

Replies inline.

> -----Original Message-----
> From: Suresh Krishnan [mailto:[email-masked]]
> Sent: Tuesday, February 28, 2012 5:47 PM
> To: Les Ginsberg (ginsberg)
> Cc: [email-masked]; [email-masked]; draft-ietf-netext-pmip-
> [email-masked]
> Subject: Re: RtgDir review: draft-ietf-netext-pmip-lr-08.txt
> 
> Hi Les,
>   Thanks for the review. Please find responses inline.
> 
> On 02/27/2012 02:28 AM, Les Ginsberg (ginsberg) wrote:
> > Although these comments are primarily for the use of the Routing
ADs,
> it
> Your understanding is correct. I will add a statement to that effect.

Could you also explain why the solutions defined do not work unless both
nodes are Mobile?
And, since you say that MN-CN is not addressed, is this something which
is planned for a future document? RFC 6279 seems to clearly include both
MN-MN and MN-nonMN (my terminology invention :-)) in the problem space
to be solved.

> > duplicate packets at times - which presumably should be no problem.
I
> am
> In the handover case, the MAG2 will continue sending packets to MAG1
> until the LMA establishes new LR state towards nMAG1, and these
packets
> will be lost. I will add text to this section to make this clear.

This is not what I was commenting on - though additional clarity in this
case would be helpful as well.
I was commenting on the initial setup of LR. I was commenting on the
statement

" The protocol does not require any synchronization between the MAGs
   before local forwarding begins."

This occurs at the end of Section 5 BEFORE the discussion of handoff in
Section 5.1.
Please respond to this comment.

> There will be no inter-LMA forwarding in this case during handover.
The
> wg decided not to handle this case (A22) because there is no defined
> inter-LMA communication mechanism in PMIPv6.

I am not commenting on A22 - which is discussed in Section 7. My comment
is regarding what happens during the handover discussed in Section 6.1.
My concern is regarding what prevents packets from being lost during the
handover. I assume that no packets are lost because the LMA will always
forward packets to an MN registered with it even if it currently
believes that LR is active/enabled - but wanted to confirm and also
suggest that mention of that point (if correct) might be clarifying.

I understand that the scenario morphs into A22 and you are not trying to
enable LR in that scenario. I also understand that there will not be
LMA1-LMA2 communication.

Hope this helps clarify my original comment.

> These are inherited from the base PMIP RFC (RFC5213). Would you still
> like me to add the expansions here?

I have been advised in the past on drafts I have co-authored that
defining all acronyms is necessary - even if they are defined in a
reference. I think this is motivated by trying to make the reader
experience more friendly. They should not have to open another document
just to find the definition of an acronym.

   Les
 
> Thanks
> Suresh