Subject: RE: [Sip] I-D ACTION:draft-mills-sip-access-network-info-01.txt

From: [email-masked]
Date: Fri, 10 May 2002 13:38:05 +0100

All,

The P-Access-Network-Info header draft (version 01) has been available for
some time now, and I have received very few comments related to it.

Does this mean there are no problems with the draft?

Regards,

Duncan

-----Original Message-----
From: [email-masked] [mailto:[email-masked]]
Sent: 03 May 2002 12:28
To: IETF-Announce
Cc: [email-masked]
Subject: [Sip] I-D ACTION:draft-mills-sip-access-network-info-01.txt

A New Internet-Draft is available from the on-line Internet-Drafts
directories.

	Title		: The SIP Access Network Info header
	Author(s)	: D. Mills
	Filename	: draft-mills-sip-access-network-info-01.txt
	Pages		: 5
	Date		: 02-May-02
	
This document defines the private SIP extension header
P-Access-Network-Info. This mechanism is useful in SIP networks that
are partitioned, such as 3G wireless networks which are partitioned at
the SIP layer into 'access' and 'home' networks. SIP User Agents may
use this header to relay information about the access network to
serving proxies in their home network. The serving proxy may then use
this information to optimize services for the UA. For example, a 3GPP
terminal uses this header to pass information about the access network
such as radio access technology and cell ID to its home service.

A URL for this Internet-Draft is:
http://www.ietf.org/internet-drafts/draft-mills-sip-access-network-info-01.t
xt

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From: "Bob Penfield" <[email-masked]>
Date: Fri, 10 May 2002 16:38:34 -0400

Hi,

1) The examples given in section 4 (a laptop in an airport or hotel) do not
sound like access networks that will provide the "transitive trust" required
to protect privacy as described in section 6. Are these really valid
examples for usage of this header? Or are you assuming that this would only
work for local ISPs and airports that had a business relationship with the
home network? How does the UA know if these types of access networks can be
trusted?

2) Does this draft need an explicit Applicability Statement?

3) Section 6 says:

    The serving proxy MUST delete this header before
    forwarding the message outside of the its domain.

but section 7 says:

    A serving proxy, typically located in the home network, and therefore
    trusted, SHOULD delete the header when the SIP signaling is forwarded
    beyond the home network domain

and section 8 says:

    This header SHOULD always be deleted by the serving network prior to
    forwarding it outside of the home network domain, as described in
    section 7.

Is it MUST or SHOULD? Also, I think it is sufficient to have the MUST or
SHOULD once (in the Proxy behavior section) or maybe twice, and then say
"...serving proxies will delete..." in other places you need to talk about
it. I realize it is very important.

4) The document has weird characters where single quotes (i.e. ') should be.

5) You say "... where the access-type is æ3GPP-GERANÆ, the access-info
SHALL be "3GPP-CGI".", but go on to says the mapping of access-type to
access-info is defined elsewhere. Can you provide a reference? Also, I don't
think you should use the requirements language (SHALL) for an example like
this. If there are mapping requirement, they should all be included or you
should refer to a document that defines them.

6) The period is missing between 'request' and 'The' in section 7.1 "... SIP
message request The UAC SHOULD ..."

7) Section 7.1, 2nd paragraph. Should "the nature or the information" be
"the nature *of* the information"?

8) Section 7.2 is labeled "UAS behavior", but talks only about proxy
behavior. I don't think there is any UAS behavior for this header.

9) In section 7.2 you say the proxy "MAY use the contents to, e.g., provide
...". I suggest you remove the "e.g." and say something like "... MAY use
the contents to provide a different service or apply performance enhancement
measures depending on the network through which the UA is
accessing the server. For example, ....".

cheers,
(-:bob

Robert F. Penfield
Chief Software Architect
Acme Packet, Inc.
130 New Boston Street
Woburn, MA 01801
[email-masked]