Subject: [Sipping] I-D Action:draft-ietf-sipping-nat-scenarios-13.txt

From: [email-masked]
Date: Fri, 11 Jun 2010 09:15:11 -0700 (PDT)

A New Internet-Draft is available from the on-line Internet-Drafts directories.
This draft is a work item of the Session Initiation Proposal Investigation Working Group of the IETF.

	Title           : Best Current Practices for NAT Traversal for Client-Server SIP
	Author(s)       : C. Boulton, et al.
	Filename        : draft-ietf-sipping-nat-scenarios-13.txt
	Pages           : 67
	Date            : 2010-06-11

Traversal of the Session Initiation Protocol (SIP) and the sessions
it establishes through Network Address Translators (NATs) is a
complex problem.  Currently there are many deployment scenarios and
traversal mechanisms for media traffic.  This document aims to
provide concrete recommendations and a unified method for NAT
traversal as well as documenting corresponding flows.

A URL for this Internet-Draft is:
http://www.ietf.org/internet-drafts/draft-ietf-sipping-nat-scenarios-13.txt

Internet-Drafts are also available by anonymous FTP at:
ftp://ftp.ietf.org/internet-drafts/

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From: Frank Shearar <[email-masked]>
Date: Sat, 12 Jun 2010 10:55:12 +0200

> 	Title           : Best Current Practices for NAT Traversal for Client-Server SIP

Nitpicks: page 1, paragraph 1:

"it's" -> "its"
"such as Real Time Protocol" -> "such as the Real-time Transport Protocol"

Page 5, 1st paragraph under Figure 1:

"The first is when using a reliable, connection orientated transport 
protocol such as TCP, SIP has an inherent mechanism ..." rewrite as:

"The first is that when SIP uses a reliable, connection orientated 
transport protocol such as TCP, it has an inherent mechanism ...

I'll read more later today and find more nits should they exist :)

frank

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From: Frank Shearar <[email-masked]>
Date: Mon, 14 Jun 2010 19:50:23 +0200

> I'll read more later today and find more nits should they exist :)

Last paragraph of page 15: "This exonerates the need..." should be "This 
removes the need..." (To exonerate someone is to find them not guilty of 
some charges.)

Page 22 point 2 says

    2.  Secondly, the contact inserted contains to ensure that all new
        requests will be sent to the same flow.  Alternatively, a GRUU
        might have been used.  See 4.3/[RFC5626].

"the contact inserted contains" what? 'the "ob"' parameter'?

Page 23, message (3) isn't indented, where most (all?) of the other 
messages are indented 3 spaces.

frank

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From: Fabio Margarido <[email-masked]>
Date: Mon, 14 Jun 2010 15:26:24 -0300

On Sat, Jun 12, 2010 at 05:55, Frank Shearar
<[email-masked]> wrote:
> "The first is that when SIP uses a reliable, connection orientated transport
> protocol such as TCP, it has an inherent mechanism ...

Shouldn't it be "The first is when using a reliable, connection
oriented transport (...)"?

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From: Frank Shearar <[email-masked]>
Date: Mon, 14 Jun 2010 20:53:37 +0200

> oriented transport (...)"?

Well, I had to reread that sentence a number of times before I could 
figure out the structure, never mind what it was saying.

Looking at my suggestion again, perhaps this is an improvement:

The first is when SIP uses a reliable, connection orientated transport 
protocol such as TCP. In this case, SIP has an inherent mechanism ...

and then start the last sentence of the paragraph like so:

The second case is when SIP uses an unreliable transport protocol such 
as UDP, where ...

frank

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From: Fabio Margarido <[email-masked]>
Date: Mon, 14 Jun 2010 16:01:54 -0300

On Mon, Jun 14, 2010 at 15:53, Frank Shearar
<[email-masked]> wrote:
> The second case is when SIP uses an unreliable transport protocol such as
> UDP, where ...

Hi Frank.
I believe your suggestion is fine, I was just pointing that
'orientated' should be changed to 'oriented'.
Best regards.

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From: Frank Shearar <[email-masked]>
Date: Mon, 14 Jun 2010 22:27:40 +0200

> 'orientated' should be changed to 'oriented'.

Oh, right. I _think_ it's acceptable English to use either form. My own 
preference is for "oriented". This URL[1] says that "orientated" is the 
general British preference, while "oriented" is prevalent in technical 
use and in the US.

frank

[1]http://www.askoxford.com/asktheexperts/faq/aboutgrammar/oriented

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From: Frank Shearar <[email-masked]>
Date: Fri, 18 Jun 2010 10:32:02 +0200

>> Title : Best Current Practices for NAT Traversal for Client-Server SIP
<snip>
> I'll read more later today and find more nits should they exist :)

Section 5.2.2
Sometimes the draft refers to 'endpoint independent mapping', sometimes 
to 'Endpoint-Independent Mapping' and sometimes to 'Endpoint Independent 
Mapping'. Since RFC 5780 uses 'Endpoint-Independent Mapping', we should 
stick with this form throughout.

Section 5.2.1.1, first sentence: "It is possible to traverse media 
through an 'Endpoint Independent NAT using STUN." Where does the missing 
single quote go? Should it be 'Endpoint-Independent Mapping' or 
'Endpoint-Independent Filtering' or just 'Endpoint-Independent'?

Section 6.1:
"Since this translations ..." should be "Since these translations ..."

This mail completes my grammar nitpicking of this draft.

Thanks!

frank