Re: [Gen-art] Gen-art review of draft-ietf-dime-pmip6-lr-07

[Qin Wu <[e-mail]>]

Hi, Elwyn:
Thank for your followup comments, please see my replies inline.

Regards!
-Qin
----- Original Message ----- 
From: "Elwyn Davies" <[e-mail]>
To: "Qin Wu" <[e-mail]>
Cc: "General Area Review Team" <[e-mail]>; <[e-mail]>
Sent: Wednesday, February 08, 2012 6:58 PM
Subject: Re: [Gen-art] Gen-art review of draft-ietf-dime-pmip6-lr-07


> Hi, Qin.
> 
> Thanks for your quick reponse.. some comments in line (I have deleted
> the bits agreed),
> 
> /Elwyn
> 
> On Fri, 2012-02-03 at 12:53 +0800, Qin Wu wrote:
>> Hi,Elwyn:
>> Thank for your valuable review. please see our replies below.
>> ----- Original Message ----- 
>> From: "Elwyn Davies" <[e-mail]>
>> To: "General Area Review Team" <[e-mail]>
>> Cc: <[e-mail]>
>> Sent: Thursday, February 02, 2012 9:06 PM
>> Subject: Gen-art review of draft-ietf-dime-pmip6-lr-07
>> 
>> 
>> >I am the assigned Gen-ART reviewer for this draft. For background on
>> > Gen-ART, please see the FAQ at
>> > < http://wiki.tools.ietf.org/area/gen/trac/wiki/GenArtfaq>.
>> > 
>> > Please wait for direction from your document shepherd
>> > or AD before posting a new version of the draft.
>> > 
>> > Document: draft-ietf-dime-pmip6-lr-07.txt
>> > Reviewer: Elwyn Davies
>> > Review Date: 2 February 2012
>> > IETF LC End Date: 24 January 2012
>> > IESG Telechat date: 16 February 2012
>> > 
>> > Summary:
>> > I have a couple of queries/minor issues regarding checking whether LMA1
>> > and LMA2 are the same node and some hand waving over the idea of
>> > 'localized routing setup/signaliing'.  There are also a few minor nits.
>> > Otherwise this is ready for the IESG.
>> > 
>> > [This document missed the normal gen-art last call allocation
>> > notification mechanism for some reason - so I didn't realize it was on
>> > my allocation till the end of last call and as a result the review is a
>> > bit late.]
>> > 
>> > Major issues:
>> > None
>> > 
>> > Minor issues:
>> > s5.1, para 3 and s5.2, last para:
>> > In s5.1:
>> >> MAG1 can verify
>> >>    whether both MAGs are under the same LMA by comparing the addresses
>> >>    of LMA1 and LMA2.
>> > Is this guaranteed to work?  Should we care? Or is this just too bad if
>> > the LMA has multiple addresses and the two MNs have different ideas?
>> 
>> [Qin]: In the example described in the s5.1, we don't consider one LMA has two LMA address.
>> LMA1 and LMA2 may represent two different mobility entities identified by LMA1 adress and LMA2 adress respectively.
>> If LMA1 address is LMA2 address, this just indicate LMA1 and LMA2 are the same mobility entity.
>> Even one LMA have more than one LMA address, this still work since MAG can know if these LMA addresses come from
>> the same mobility entity based on MN1 and MN2's binding update list.
>> 
>> > However in s5.2:
>> >> In the case where MNs share the same LMA, LR should be initiated by
>> >>    LMA1 (i.e.,LMA2) since only LMA1 knows that both MN1 and MN2 belong
>> >>    to itself by looking up the binding cache entries corresponding to
>> >>    MN1 and MN2. 
>> > I am unsure whether these two statements are talking about the same
>> > thing - and, if so, are they contradictory?
>> > 
>> 
>> [Qin]: No Confliction, See above.
> 
> I think this is exactly the point: You give two different (but allegedly
> non-conflicting ways) of doing the same thing at two places in the
> draft.  From what you say, I infer that you could do either thing in
> both cases. If so then it would be better to give the alternatives
> together for the first case and refer to the previous comments when the
> second case is reached in the text.

[Qin]: Good suggestion and will follow this.
> 
>> 
>> > s5.1, last para:
>> >> Figure 4 shows another example scenario, similar to the example
>> >>    scenario illustrated in Figure 3, LMA1 does not respond to MAG1 with
>> >>    the address of LMA2, instead setting up a localized routing path
>> >>    directly between itself and LMA2 via localized routing signaling.
>> > I am unsure what 'localized routing signaliing' would involve.  What
>> > would the nodes do for this?  Appears to involve some waving of hands.
>> 
>> [Qin]: LMA1 and LMA2 exchange to trigger corresponding LMA to setup binding entries
>> on the correspoding MAG for localized routing and establish localized
>> routing path between MAG1 and MAG2.
>> 
>> > On a slightly broader point, there are a number of places where the
>> > phrase 'localized routing setup' (or similar) is used.  It would, I
>> > think, be useful to add a few words indicating what is thought to be
>> > involved although actually doing it is clearly out of scope of this
>> > document.
>> 
>> [Qin]: Okay.
> 
> I am afraid this doesn't really help: You say 'establish localized
> routing path between MAG1 and MAG2'. How? Does this imply that the MAG
> or some other component will (re-)configure the local packet routing
> infrastructure? (Not something I would expect the MAG to be authorized
> to do.) Or is this a matter of creating a tunnel?  I think this needs to
> be a whole lot more concrete - both ends have to be expecting the
> packets and know what to do with them.

[Qin]: Yes, your are right. Tunneling between MAG1 and MAG2 should be configured on both MAGs.
As default static behavior,tunnel between MAG1 and MAG2 uses the same encapsulation mechanism
as that being used for PMIP tunnel between MAG and LMA. In this case, MAG1 and MAG2
can start using the same tunneling mechanism without special configuration (e.g.using other 
tunnel mechanism that is uniform in the PMIP domain) on MAGs or dynamic tunneling negotiation between MAGs.
but special configuration on MAGs or dynamic tunnel negotiation can overide 
the default static behavior mentioned above if they are really needed.

Hope this clarifies.

> Regards,
> Elwyn  
> 
>