Subject: [Ecrit] draft-ietf-ecrit-local-emergency-rph-namespace-00

From: "James M. Polk" <[email-masked]>
Date: Mon, 27 Oct 2008 19:32:14 -0500

ECRIT WG

Here is a update to a ID I think is pretty near done, given that this 
is merely an IANA registration ID of an existing mechanism.

Comments are wanted

>A New Internet-Draft is available from the on-line Internet-Drafts 
>directories.
>This draft is a work item of the Emergency Context Resolution with 
>Internet Technologies Working Group of the IETF.
>
>
>         Title           : IANA Registering a SIP Resource Priority 
> Header Namespace for Local Emergency Communications
>         Author(s)       : J. Polk
>         Filename        : 
> draft-ietf-ecrit-local-emergency-rph-namespace-00.txt
>         Pages           : 9
>         Date            : 2008-10-27
>
>This document creates and IANA registers the new Session Initiation
>Protocol (SIP) Resource Priority header (RPH) namespace "esnet" for
>local emergency usage to a public safety answering point (PSAP),
>between PSAPs, and between a PSAP and first responders and their
>organizations.
>
>A URL for this Internet-Draft is:
>http://www.ietf.org/internet-drafts/draft-ietf-ecrit-local-emergency-rph-namespace-00.txt
>
>
>
><ftp://ftp.ietf.org/internet-drafts/draft-ietf-ecrit-local-emergency-rph-namespace-00.txt>

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From: Janet P Gunn <[email-masked]>
Date: Mon, 27 Oct 2008 23:45:43 -0400

I apologize for not tracking this as closely as I meant to, as these 
comments apply to  earlier versions as well.

This sentence at the end of sec 1 doesn't quite work.
"This document IANA registers the "esnet"
   RPH namespace for use within emergency services networks, not just 
   of those from citizens to PSAPs." (no clear antecedent for "those")

Perhaps
"This document IANA registers the "esnet"
   RPH namespace for use within emergency services networks, not just for 
calls or sessions
    from citizens to PSAPs."

Section 2 says
 "This document updates the behaviors of the SIP Resource Priority 
   header, defined in [RFC4412], during the treatment options 
   surrounding this new "esnet" namespace only. The usage of the 
   "esnet" namespace does not have a normal, or routine call level. 
   Every use of this namespace will be in times of an emergency, where 
   at least one end of the signaling is with a local emergency 
   organization."

I don't see this as an "update of the behavior of 4412".  Neither the ets 
namespace not the wps 
namespace have a "normal" or "routine" call level.  Every use of the wps 
and ets namespaces will 
have priority over calls without RPH.

You say "This 
   namespace, therefore, MAY be overwritten or deleted, contrary to the
   rules of RFC 4412 [RFC4412]." 

It is not clear to me why this is "contrary to the rules of 4412".  It is 
certainly anticipated 
that other RPH will be overwritten or deleted, when the UAS understands 
the namespace.

4412 says "Existing implementations of RFC 3261 that do not participate in 
the
   resource priority mechanism follow the normal rules of RFC 3261,
   Section 8.2.2: "If a UAS does not understand a header field in a
   request (that is, the header field is not defined in this
   specification or in any supported extension), the server MUST ignore
   that header field and continue processing the message". "

But I do not see anywhere that is says that a UAS that DOES understand the 
namespace is 
forbidden from deleting it.  For instance, sec 4.7.1 of 4412 says that 
"the UAC
   MAY attempt a subsequent request with the same or different resource
   value."  This certainly implies the ability to overwrite or delete an 
RPH namespace. 

(See also, for instance the PTSC SAC document on the use of the ets and 
wps namespaces)

Immediately following these statements, you give 3 options-
"These proxies in the service provider 
   MAY either 

   o  accept the existing RPH value with "esnet" in it, if one is
      present, and grant relative preferential treatment to the request 
      when forwarding it to the ESINet.

   o  replace any existing RPH value, if one is present, and insert an 
      "esnet" namespace and give relative preferential treatment to the 
      request when forwarding it to the ESINet.

   o  insert an "esnet" namespace in a new RPH and give relative 
      preferential treatment to the request when forwarding the SIP 
      request towards the ESINet."

Why do you exclude the possibility of adding the esnet RPH value without 
"replacing" an existing RPH value?

Finally, there is another point that  needs to be made clear.  At least 
one person has contacted me expressing concern that this ID implied that 
the esnet namespace would  have priority over other namespaces (in 
particular wps and ets).  I assured him that this was not the case, that 
there was nothing prevent the expected behavior - that the ets and wps 
namespaces would be prioritized ahead of esnet in GETS Service Provider 
networks.

However, since the question has already arisen, it would be a good idea to 
clarify  this, perhaps in  section 3, where you discuss  the other 
namespaces.  In particular, it needs to be made clear in section 3.2 that, 
even if  "the   local jurisdiction preferred to preempt normal calls in 
lieu of 
   completing emergency calls. ", esnet calls will NOT preempt wps or ets 
calls.

By the way, I think you mean "the   local jurisdiction preferred to 
preempt normal calls in order to complete emergency calls. "  - not "in 
lieu of".  Or perhaps "the   local jurisdiction preferred to preempt 
normal calls in lieu of  dropping emergency calls. "

In fact, it is not clear to me that 4412 permits a call with an RPH (e.g., 
esnet)  to preempt a "normal" call (with no RPH namespace).  Section 
4.7.2.1 of 4412 says 
"4.7.2.1.  User Agent Servers and Preemption Algorithm

   A UAS compliant with this specification MUST terminate a session
   established with a valid namespace and lower-priority value in favor
   of a new session set up with a valid namespace and higher relative
   priority value, unless local policy has some form of call-waiting
   capability enabled. "

It doesn't say anything about preempting a call with no RPH

Thanks

Janet

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"James M. Polk" <[email-masked]> 
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10/27/2008 08:32 PM

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Subject
[Ecrit] draft-ietf-ecrit-local-emergency-rph-namespace-00

ECRIT WG

Comments are wanted

><
ftp://ftp.ietf.org/internet-drafts/draft-ietf-ecrit-local-emergency-rph-namespace-00.txt