Subject: [RAI] RAI-ART review of draft-loreto-simple-im-srv-label-00.txt

From: Miguel Garcia <[email-masked]>
Date: Wed, 09 Apr 2008 14:34:27 +0300

I am the assigned RAI-ART reviewer for 
draft-loreto-simple-im-srv-label-00.txt.

For background on RAI-ART, please see the FAQ at 
<http://www.softarmor.com/rai/art/rai-art-FAQ.html>.

Please resolve these comments along with any other comments you may receive.

Document: draft-loreto-simple-im-srv-label-00.txt
Reviewer: Miguel Garcia <[email-masked]>
Review Date: 2008-04-09
Review Due: 2008-04-11
Review Type: Early documents

Comments:

- I have one substantial comment. It is with respect the scope of the 
draft. It seems that the draft is trying to achieve two goals in the 
same shot: a) register a couple of SRV labels with IANA; b) Specify how 
SIP IM and Presence use DNS SRV to resolve im: and pres: URIs.

The problem is that b) is already specified in RFC 3861 Section 3. So, I 
recommend to get b) out of the scope of the draft and focus on a)

Nits:

- The title of the draft does not mention Presence, in spite it 
registers a label for the presence service. Also, remove the word 
'registry', because you don't register a 'registry', but a label in a 
registry.

- I would expect the Introduction to give a brief description (max one 
paragraph) of what SRV records are and how they are structured: 
"_Service._Proto.Name", so the text can later justify that the _im and 
_pres labels have been registered as _Service, but not _sip. The text 
should also add a reference to RFC 2782 (DNS SRV), which is relevant for 
understanding this draft.

- Section 2 says:

    However if the UA is unable to resolve the IM URI, in order to
    resolve the IM URI into corresponding SIP URI, it SHOULD perform a
    SRV lookup for:

The text hints that the UA first tries to resolve th IM URI and it if 
fails, it should try the SRV record. I don' think this is what the text 
wants to say. I think the text should say that, although there are 
standard mechanisms for resolving the im and pres URIs (refer to RFC 
3861 Section 3), the labels are not registered for SIP.

- Also, according to my first comment, I don't get the reason for the 
SHOULD strength in the following sentence:

    However if the UA is unable to resolve the IM URI, in order to
    resolve the IM URI into corresponding SIP URI, it SHOULD perform a
    SRV lookup for:

Is this draft putting a normative requirement to the SIP/SIMPLE 
application? This draft is not specifying that behavior, therefore, the 
test should use descriptive text.

- Section 2. The text is short in words around the "_pres" SRV label 
(just one sentence). Furthermore, RFC 3265 is not related to presence, 
so that RFC is not going to tell me how to resolve a pres URI. Perhaps a 
better reference is the presence event package RFC 3856.

- Security considerations. I think this draft goes beyond its scope. The 
scope of the draft is to include a registration in the IANA registry. 
The scope of this draft is not about SIP or DNS procedures, so, it 
shouldn't mention any of them. I guess a simpler text would be enough, 
such as: This document merely serves for the registration of DNS SRV 
labels in the appropriate IANA registry. The does not specify a 
protocol, therefore, there are no security issues associated with it.

- IANA considerations section. This is the core of this document. I 
think it is not accepted to refer to the "appropriate registry" here, 
when the draft says:

    the IANA
    registers the "_sip" protocol label in the appropriate registry, as
    follows:

The draft needs to explicitly mention the registry by name, which in 
this case is the 'Instant Messaging SRV Protocol Label Registry'.

The same applies to the 'Presence SRV Protocol Label Registry'.

/Miguel

-- 
Miguel A. Garcia           tel:+358-50-4804586
Nokia Siemens Networks     Espoo, Finland

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---

From: "Hisham Khartabil" <[email-masked]>
Date: Thu, 10 Apr 2008 09:20:18 +1000

On 09/04/2008, Miguel Garcia <[email-masked]> wrote:
> For background on RAI-ART, please see the FAQ at <
> http://www.softarmor.com/rai/art/rai-art-FAQ.html>.
>
> draft. It seems that the draft is trying to achieve two goals in the same
> shot: a) register a couple of SRV labels with IANA; b) Specify how SIP IM
> and Presence use DNS SRV to resolve im: and pres: URIs.
>

I agree.

Hisham

Nits:
>
> - The title of the draft does not mention Presence, in spite it registers
> a label for the presence service. Also, remove the word 'registry', because
> you don't register a 'registry', but a label in a registry.
>
> "_Service._Proto.Name", so the text can later justify that the _im and _pres
> labels have been registered as _Service, but not _sip. The text should also
> add a reference to RFC 2782 (DNS SRV), which is relevant for understanding
> this draft.
>
> - Section 2 says:
>
> wants to say. I think the text should say that, although there are standard
> mechanisms for resolving the im and pres URIs (refer to RFC 3861 Section 3),
> the labels are not registered for SIP.
>
> application? This draft is not specifying that behavior, therefore, the test
> should use descriptive text.
>
> - Section 2. The text is short in words around the "_pres" SRV label (just
> one sentence). Furthermore, RFC 3265 is not related to presence, so that RFC
> is not going to tell me how to resolve a pres URI. Perhaps a better
> reference is the presence event package RFC 3856.
>
> scope of the draft is to include a registration in the IANA registry. The
> scope of this draft is not about SIP or DNS procedures, so, it shouldn't
> mention any of them. I guess a simpler text would be enough, such as: This
> document merely serves for the registration of DNS SRV labels in the
> appropriate IANA registry. The does not specify a protocol, therefore, there
> are no security issues associated with it.
>
> - IANA considerations section. This is the core of this document. I think
> it is not accepted to refer to the "appropriate registry" here, when the
> draft says:
>
>   the IANA
> The draft needs to explicitly mention the registry by name, which in this
> case is the 'Instant Messaging SRV Protocol Label Registry'.
>