Subject: Re: [Sip] bis draft: Headers in 100 Trying (was "Minor NIT on Sup ported header")

From: Jonathan Rosenberg <[email-masked]>
Date: Tue, 08 Jan 2002 14:42:56 -0500

Drage, Keith (Keith) wrote:

>>>Does anybody see any purpose for any headers other than From; To;
>>>
>>Call-ID;
>>
>>>CSeq; Via; and Content-Length within a 100 Trying response.
>>>
>>In addition to the two Vijay mentioned (Server and Timestamp), I don't see
>>anything wrong with including Date.  Some servers, including ours, insert
>>it
>>in every message generated.  (In a 100 it's probably roughly as useful as
>>Server, i.e. it's good for debugging and for diagnosing various abnormal
>>situations.)
>>
>>
> See previous mail concerning why I think Server and Timestamp are not
> applicable. Having reread the bis draft concerning Date, I can see that this
> is applicable.

Timestamp is most definitely applicable to 100, as this is the only 
response it is useful for.

> 
> 
>>Bis says that Record-Route headers MAY be present in a provisional
>>response,
>>and doesn't separate out 100 Trying from other 1xx responses.  I can
>>imagine scenarios where Record-Route in a 100 could be useful, but I'm not
>>sure how plausible they are.  
>>
>>
> Yes, I can see that the current rules allow a proxy to respond. This would
> only appear to have any impact on the call from a 1st proxy back to a UAC,
> as it is only the UAC that sent the request in the first place that can use
> the accumulated Record-Route information. Now I am stuck to see how useful
> that usage is.

I do not think Record-Route or Contact is appropriate in 100. According 
to bis-05, it is actually allowed, since the spec says that 1xx/2xx to 
INVITE create dialogs, and dialog-creating responses have those things. 
However, I believe this to be an error in the spec, and that rather, 
101-199/2xx to INVITE create dialogs. We will fix this.

-Jonathan R.

-- 
Jonathan D. Rosenberg, Ph.D.            72 Eagle Rock Avenue
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