Subject: [Gen-art] Gen-ART review of draft-ietf-ecrit-psap-callback-10

From: "Vijay K. Gurbani" <[email-masked]>
Date: Fri, 20 Sep 2013 11:39:11 -0500

[Resending ... had the wrong address for Roger Marshall.  Sorry. ]

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 resolve these comments along with any other Last Call comments
you may receive.

Document: draft-ietf-ecrit-psap-callback-10
Reviewer: Vijay K. Gurbani
Review Date: Sep-20-2013
IETF LC End Date: Sep-27-2013
IESG Telechat date: Unknown

This draft is basically ready for publication, but has a couple of
minor issues that should be fixed (or at least looked at) before
publication.

Major: 0
Minor: 2
Nits:  4 (to improve readability)

Minor:
- S5.2: Maybe I am missing something here, but I did not see any
  proposed requirement as I read the text until this point.  At least I
  do not see a explicit requirement.

  The text in S5.1 constitutes an implicit requirement in that it asks
  the SIP UA to override user interface configurations when an incoming
  call has "Priority: psap-callback" header AND the SIP UA has recently
  placed a call to an emergency service.  Is this the requirement you
  allude to in the first sentence of S5.2?  If so, may be better to
  explicitly pose this as a requirement.

  The second paragraph of S5.2 constitutes a separate requirement.

  Is it worth spelling these out explicitly as requirements?

- S5.3, last paragraph: It seems to me that the SIP UA is the authority
  insofar as it can maintain state that an emergency call was made a
  short while ago.  Consequently, it would seem beneficial to couple the
  presence of the callback marking with this state and override local UA
  behaviour.

  At least, this alleviates the eventuality that somehow the VoIP
  provider forgot to scrub the marking AND the UA never made an emergency
  call (thereby allowing spam through).

  Now, if it is your intent to keep the UA as stateless as possible, then
  overriding local UA behaviour based on solely the callback marking is
  fine.  But I do not know what your assumptions are here with respect to
  state maintained in the UA.  So please determine if this approach of
  asking UA to couple state information with the marking makes sense or
  not.  If not, feel free to disregard, but I did want to point it out.

Nits:
- S3, first paragraph: "As explained in Section 1 a SIP entity examines
  an incoming PSAP callback by comparing the domain of the PSAP with the
  destination domain of the emergency call."

  Here, I would suggest adding a small phrase as follows:

  s/destination domain of the emergency call./destination domain of the
  outbound emergency call placed earlier./

- S3.1: s/synchronized as to state/synchronized,/
  This improves readability since the text as it currently stand is hard
  to parse.

- S3.3, second paragraph: s/Similarly to/Similar to/

- S3.5, first paragraph: s/later does leave/later leaves/

Thanks,

- vijay
-- 
Vijay K. Gurbani, Bell Laboratories, Alcatel-Lucent
1960 Lucent Lane, Rm. 9C-533, Naperville, Illinois 60563 (USA)
Email: vkg@{bell-labs.com,acm.org} / [email-masked]
Web: http://ect.bell-labs.com/who/vkg/  | Calendar: http://goo.gl/x3Ogq