Subject: [Ecrit] Question on ecrit using Priority header

From: Hadriel Kaplan <[email-masked]>
Date: Thu, 8 Nov 2012 19:24:32 +0000

I hate to raise this question, but apparently I don't hate it enough not to go ahead and raise it anyway:
Is the Priority header really sufficient for ECRIT's use, as described in draft-ietf-ecrit-psap-callback-06?  

The Priority header was never meant to affect SIP processing... not even routing decisions nor blocking/barring I believe.  It's really more like the important flag in email (i.e., it's like the Mail 'Importance' header, as opposed to the Mail 'Priority' header).

So isn't this the wrong header?

-hadriel

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From: Christer Holmberg <[email-masked]>
Date: Thu, 8 Nov 2012 19:30:44 +0000

Hi, 

>The Priority header was never meant to affect SIP processing... not even routing decisions nor blocking/barring I believe.  
>It's really more like the important flag in email (i.e., it's like the Mail 'Importance' header, as opposed to the Mail 'Priority' header).

RFC 3261 says:

"For example, it may be factored into decisions about call routing and acceptance."

>So isn't this the wrong header?

No.

Regards,

Christer

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From: Robert Sparks <[email-masked]>
Date: Thu, 08 Nov 2012 14:31:53 -0500

From 3261:

20.26 Priority

    The Priority header field indicates the urgency of the request as
    perceived by the client.  The Priority header field describes the
    priority that the SIP request should have to the receiving human or
    its agent.  For example, it may be factored into decisions about call
    routing and acceptance.

On 11/8/12 2:24 PM, Hadriel Kaplan wrote:
> _______________________________________________
> Ecrit mailing list
> [email-masked]
> https://www.ietf.org/mailman/listinfo/ecrit

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From: "Rosen, Brian" <[email-masked]>
Date: Thu, 8 Nov 2012 14:34:03 -0500

Ooh, ooh, am I first?

>From 3261:
  The Priority header field describes the
   priority that the SIP request should have to the receiving human or
   its agent.  For example, it may be factored into decisions about call
   routing and acceptance.  

Did you catch the part about "decisions about call routing"?

Brian

---

From: Hadriel Kaplan <[email-masked]>
Date: Thu, 8 Nov 2012 19:38:37 +0000

Oh sure, point out the actual RFC text.  How boring.
Someone should have said RTFM. :)

-hadriel

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From: James Polk <[email-masked]>
Date: Thu, 08 Nov 2012 13:47:56 -0600

yeah - but you were there, if not the WG chair at the time, when SIP 
decided the Priority header was *not* enough for processing decisions 
within a SIP entity, meaning this flag does not affect the priority 
of the message or invoke certain behaviors. Many said that sending a 
request marked with a certain Priority value one way (i.e., next hop 
routing) and a message towards the same destination with a different 
Priority value another way is not inconsistent with how that SIP 
entity treats the request. IIRC Priority header values can affect 
routing, which is not affecting the priority of the message within 
any SIP entity (I think I said that more than once here).

And to Hadriel's point, it's really pushing the use and/or intent of 
Priority:. Very few  wanted to use RPH though, so that idea died...

James

At 01:34 PM 11/8/2012, Rosen, Brian wrote:
> > I hate to raise this question, but apparently I don't hate it 
> enough not to go ahead and raise it anyway:
> > Is the Priority header really sufficient for ECRIT's use, as 
> described in draft-ietf-ecrit-psap-callback-06?
> >
> > The Priority header was never meant to affect SIP processing... 
> not even routing decisions nor blocking/barring I believe.  It's 
> really more like the important flag in email (i.e., it's like the 
> Mail 'Importance' header, as opposed to the Mail 'Priority' header).
> >

---

From: Robert Sparks <[email-masked]>
Date: Thu, 08 Nov 2012 14:59:03 -0500

If you read two more sentences down from what several people have quoted 
now, you'll find:

The Priority header field does not influence the use of
    communications resources such as packet forwarding priority in
    routers or access to circuits in PSTN gateways.

RjS

On 11/8/12 2:47 PM, James Polk wrote:
> within a SIP entity, meaning this flag does not affect the priority of 
> the message or invoke certain behaviors. Many said that sending a 
> routing, which is not affecting the priority of the message within any 
> SIP entity (I think I said that more than once here).
>
>> > The Priority header was never meant to affect SIP processing... not 
>> even routing decisions nor blocking/barring I believe.  It's really 
>> more like the important flag in email (i.e., it's like the Mail 
>> 'Importance' header, as opposed to the Mail 'Priority' header).
>> >

---

From: "DRAGE, Keith (Keith)" <[email-masked]>
Date: Thu, 8 Nov 2012 21:22:11 +0100

And there is no reason why one cannot use the Resource-Priority header field in conjunction with this to do the things that Resource-Prioirty is designed to do, if you need those capabilities.

Part of this depends on whether you need priority of the the signalling or media on emergency callbacks. Not everyone needs it for emergency call, and fewer still need it for the callbacks.

Keith

________________________________
From: [email-masked] [mailto:[email-masked]] On Behalf Of Robert Sparks
Sent: 08 November 2012 19:59
To: James Polk
Cc: Rosen, Brian; Ecrit
Subject: Re: [Ecrit] Question on ecrit using Priority header

If you read two more sentences down from what several people have quoted now, you'll find:

RjS

On 11/8/12 2:47 PM, James Polk wrote:
yeah - but you were there, if not the WG chair at the time, when SIP decided the Priority header was *not* enough for processing decisions within a SIP entity, meaning this flag does not affect the priority of the message or invoke certain behaviors. Many said that sending a request marked with a certain Priority value one way (i.e., next hop routing) and a message towards the same destination with a different Priority value another way is not inconsistent with how that SIP entity treats the request. IIRC Priority header values can affect routing, which is not affecting the priority of the message within any SIP entity (I think I said that more than once here).

And to Hadriel's point, it's really pushing the use and/or intent of Priority:. Very few  wanted to use RPH though, so that idea died...

James

Ooh, ooh, am I first?

Brian

On Nov 8, 2012, at 2:24 PM, Hadriel Kaplan <[email-masked]><mailto:[email-masked]> wrote:

> [email-masked]<mailto:[email-masked]>

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