> -----Original Message-----
> From: Victor Kueh [mailto:[EMAIL PROTECTED]]
> Sent: Friday, March 02, 2001 2:58 PM
> To: [EMAIL PROTECTED]
> Subject: [Sip-implementors] Query on delay
>
>
> Dear All,
>
> Sorry if these questions seem trivial, but I wouild
> appreciate if someone out there who know the answers could help.
>
> What is the definition of call setup delay in SIP? Is it
> from the time the UAC sends the INVITE to the time it gets a
> provisional
> response? And does this provisional response has to be issued
> by a UAS or
> the one issued by a proxy will do (they will be different
> since the one
> issued by the proxy will reach the UAC faster)
The spec does not define metrics as these. It would be the job of some other
organization or document to define terms like "calls per second" and "call
setup delay" as they relate to SIP.
I belive call setup delay generally refers to the delay between completion
of dial and hearing ringback. Tony Eyers and Henning Schulzrinne did some
work to study the distribution of these delays using SIP over real networks;
see:
http://www.fokus.gmd.de/events/iptel2000/pr/signaling_talk.pdf
for some definitions and results.
>
> Also does anyone know what is the mean value for DNS
> lookup time? How about the mean value for the location server
> to search
> its database for current location of the UAS? (I know these
> values vary
> depending on the processing speed, etc, but what are the
> typical/average
> values)
Since SIP doesn't even define what this is, it is impossible to answer what
its delays are. The location service is an abstract concept in SIP. It can
be an LDAP database, Oracle database, local file, in-memory database, result
of program execution, etc., all of which will have wildly differing delay
characteristics.
-Jonathan R.
---
Jonathan D. Rosenberg 72 Eagle Rock Ave.
Chief Scientist First Floor
dynamicsoft East Hanover, NJ 07936
[EMAIL PROTECTED] FAX: (973) 952-5050
http://www.cs.columbia.edu/~jdrosen PHONE: (973) 952-5000
http://www.dynamicsoft.com
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