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

["Les Ginsberg (ginsberg)" <[e-mail]>]

Suresh -

Replies inline.

> -----Original Message-----
> From: Suresh Krishnan [mailto:[e-mail]]
> Sent: Tuesday, February 28, 2012 5:47 PM
> To: Les Ginsberg (ginsberg)
> Cc: [e-mail]; [e-mail]; draft-ietf-netext-pmip-
> [e-mail]
> 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:
> > (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.
> 
> 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.

> 
> >
> > 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?
> 
> 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.

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

> 
> >
> > 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?
> 
> 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
>