Re: [Sip] Comparison of retargeting proposals

["Ian Elz" <ian.elz at ericsson.com>]

Francois,

You have missed one vital issue relating to History-Info.

You cannot use a tel URI in History-Info as RFC3966 does not allow you
to use header parameters. H-I uses header parameters for Reason and
Privacy in H-I entries.

To use a tel URI in a H-I entry requires that you convert it to a sip
URI which requires that a suitable domain be found to create a valid
entry.

-----Original Message-----
From: Francois Audet [mailto:audet at nortel.com] 
Sent: 01 April 2008 17:30
To: Mary Barnes; Hans Erik van Elburg; Juha Heinanen; Christer Holmberg
Cc: sip at ietf.org; DOLLY, MARTIN C, ATTLABS
Subject: Re: [Sip] Comparison of retargeting proposals

The biggest problems with History-Info (IMHO) are:

- It is written so that the UAC may generate the first History-Info
entry
  or (more typically), it's proxy will. Creates some confusion on who
does what.
- It's optional
- The number of entries can be pruned by proxies, making the content
unreliable.
- The last hop (i.e., replacing with contact) is not made obvious in the
list (the
  whole point of this discussion).
- People have used it as a replacement to diversion-header, i.e., to map
to 
  ISDN redirection number information. <--- This is the biggest problem

All of those could be solve by a -bis.

(There are also a few minor mistakes in some of the flows).

> -----Original Message-----
> From: Barnes, Mary (RICH2:AR00) 
> Sent: Tuesday, April 01, 2008 06:28
> To: Hans Erik van Elburg; Audet, Francois (SC100:3055); Juha 
> Heinanen; Christer Holmberg
> Cc: sip at ietf.org; DOLLY, MARTIN C, ATTLABS
> Subject: RE: [Sip] Comparison of retargeting proposals
> 
> The proper use of History-Info isn't rocket science, but it 
> does require careful reading of the spec and proper 
> implementation (i.e., I agree if you don't implement the spec 
> properly, then it is a mess but that can be the case for any 
> spec that isn't implemented properly). There are some 
> inaccuracies in one of Dale's examples on forking that makes 
> it look far more error prone and problematic than it should 
> be. I'll respond separately with details.  
> 
> Mary. 
> 
> -----Original Message-----
> From: sip-bounces at ietf.org [mailto:sip-bounces at ietf.org] On 
> Behalf Of Hans Erik van Elburg
> Sent: Tuesday, April 01, 2008 3:07 AM
> To: Audet, Francois (SC100:3055); Juha Heinanen; Christer Holmberg
> Cc: sip at ietf.org; DOLLY, MARTIN C, ATTLABS
> Subject: Re: [Sip] Comparison of retargeting proposals
> 
> The point is that History-Info does not solve the problem so 
> something new is needed anyway.
> 
> And proper use of History-Info is rocket science as Dale has shown.
> 
> /Hans Erik
> 
> -----Original Message-----
> From: sip-bounces at ietf.org [mailto:sip-bounces at ietf.org] On 
> Behalf Of Francois Audet
> Sent: Tuesday, April 01, 2008 2:16 AM
> To: Juha Heinanen; Christer Holmberg
> Cc: sip at ietf.org; DOLLY, MARTIN C, ATTLABS
> Subject: Re: [Sip] Comparison of retargeting proposals
> 
> There are existing implementations of History-Info in the field.
> 
> It's not rocket science.
> 
> And I don't see why introducing something else will be 
> simpler. It will just be extra complexity. 
> 
> > -----Original Message-----
> > From: sip-bounces at ietf.org [mailto:sip-bounces at ietf.org] On 
> Behalf Of 
> > Juha Heinanen
> > Sent: Saturday, March 29, 2008 05:48
> > To: Christer Holmberg
> > Cc: sip at ietf.org; DOLLY, MARTIN C, ATTLABS
> > Subject: Re: [Sip] Comparison of retargeting proposals
> > 
> > Christer Holmberg writes:
> > 
> >  > However, I still fail to understand how Target would be more 
> > "complex"
> >  > than e.g. History-Info. 
> > 
> > christer,
> > 
> > ANY solution for anything must be MUCH simpler than history-info, 
> > which is far too complex by itself.
> > 
> > i haven't seen anyone fully implement history-info and most likely 
> > that is because of its complexity.  if you are now going to invent 
> > some other mechanism that is as complex or even more 
> complex, it has 
> > no change in real world.
> > 
> > i therefore suggest that h-i is deprecated and a replaced 
> by a simpler
> 
> > mechanism.
> > 
> > -- juha
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> > 
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> This list is for NEW development of the core SIP Protocol Use 
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> This list is for NEW development of the core SIP Protocol Use 
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> Use sipping at ietf.org for new developments on the application of sip
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