Subject: Re: [dhcwg] Alvaro Retana's Discuss on draft-ietf-dhc-dynamic-shared-v4allocation-07: (with DISCUSS)

From: Qi Sun <[email-masked]>
Date: Thu, 28 May 2015 11:25:46 +0800

Dear Alvaro,

Thanks for the review. Please see inline.

On May 28, 2015, at 10:47 AM, Alvaro Retana <[email-masked]> wrote:

> 
> ----------------------------------------------------------------------
> DISCUSS:
> ----------------------------------------------------------------------
> 
> Section 2 (Applicability Statement) says that “this extension is only
> suitable for specific architectures based on the Address plus Port model
> (A+P) [RFC6346]”, which I take to mean that the components of the
> solution in RFC6346 must be present (PRR, for example).  In fact, if the
> functionality described in RFC6346 is not present, then the forwarding
> won’t work as standard destination-based protocols may not deliver the
> packets to the right place.  I think that RFC6346 should be a Normative
> Reference, which then results in a DOWNREF to an Experimental RFC.
> 
> IOW, if the functionality in RFC6346 is needed (which I think it is),
> then the status of this document should not be Standards Track.
> 
> 

IMO, RFC6346 provides an architecture of A+P, while [I-D.ietf-softwire-lw4over6] and [I-D.ietf-softwire-map] follow RFC6346 for sharing IPv4 in the context of IPv4-over-IPv6 tunnelling. Those two documents are being published as Standard Track by the IETF. 

This document intends to define a provisioning method (a DHCPv4 option used with DHCPv4 over DHCPv6 [RFC7341]), not another A+P IPv6 transition mechanism. In the Section 2, we’re trying to make it clear that this mechanism is not universally applicable. It’s only suitable for “[I-D.ietf-softwire-lw4over6] and certain configurations of  [I-D.ietf-softwire-map]”, which are on Standard Track and are normative referenced in this document. We think that would sufficiently avoid potential mis-use of this mechanism.

Hope the explanation could help to resolve your concern.

Thanks! 
Qi

---

From: Ted Lemon <[email-masked]>
Date: Thu, 28 May 2015 03:44:57 +0000

> then the status of this document should not be Standards Track.

Actually, the text you quote does not say that this extension is only suitable for use with RFC 6346, but rather that it is only suitable for use with architectures _based_ on 6346.   Several of these have been defined, and were approved by the IETF on the standards track, and indeed the first two normative references in this document refer to two such documents.   So I don't think you've identified a problem, unless I'm missing something here.   As a general rule what it means for something to be a normative reference is that you couldn't implement the document making the reference without reading the normative reference.   That would clearly not be the case for RFC 6346 with respect to the shared-v4allocation draft.

That said, it might be cleaner for this text to refer to the lw4over6 and map-t documents; I think the reason it does is to leave the door open for other documents based on 6346 other than those two.   However, I really don't think that this change is DISCUSS-worthy!   :)

---

From: "Alvaro Retana (aretana)" <[email-masked]>
Date: Thu, 28 May 2015 11:25:45 +0000

On 5/27/15, 11:25 PM, "Qi Sun" <[email-masked]> wrote:

Qi:

Hi!

>In the Section 2, we¹re trying to make it clear that this mechanism is
>not universally applicable. It¹s only suitable for
>³[I-D.ietf-softwire-lw4over6] and certain configurations of
>[I-D.ietf-softwire-map]², which are on Standard Track and are normative
>referenced in this document. We think that would sufficiently avoid
>potential mis-use of this mechanism.

This is the source of my concern.  The current text says this:

   The solution allows multiple hosts to be simultaneously allocated the
   same IP address.  As the IP address is no longer a unique identifier
   for a host, this extension is only suitable for specific
   architectures based on the Address plus Port model (A+P) [RFC6346]
   such as [I-D.ietf-softwire-lw4over6] and certain configurations of
   [I-D.ietf-softwire-map].

..which presents the two Standards Track documents as examples (³such as²)
of RFC6346-based architectures.  What you¹re saying above is different:
this extension is not for any RFC6346-based, but specifically for those
two documents.

I would suggest changing the text so it doesn¹t sound dependent on
RFC6346.  For example:

   The solution allows multiple hosts to be simultaneously allocated the
   same IP address.  As the IP address is no longer a unique identifier
   for a host, this extension is only suitable for specific
   architectures based on the Address plus Port model (A+P) [RFC6346].
   Specifically, this document presents a solution that applies to
[I-D.ietf-softwire-lw4over6]
   and certain configurations of [I-D.ietf-softwire-map].

I think it is also necessary to clarify which configurations of
[I-D.ietf-softwire-map] are addressed (or which are not ‹ whichever is
clearer/easier).

Thanks!

Alvaro.