RE: [Ecrit] Suggestion for "performance and reliability" section

["Michael Hammer \(mhammer\)" <mhammer at cisco.com>]

I don't think it meaningful to put a number on "until human answer"
unless you intend to automate humans, or are providing some technical
analysis on average call rates and staffing at 911 PSAPs.  The latter
would be a good NENA exercise, but not sure if that is in scope of
ECRIT.

Mike
 

> -----Original Message-----
> From: ecrit-bounces at ietf.org [mailto:ecrit-bounces at ietf.org] 
> On Behalf Of Henning Schulzrinne
> Sent: Tuesday, August 02, 2005 11:57 AM
> To: Byron Smith
> Cc: ecrit at ietf.org
> Subject: Re: [Ecrit] Suggestion for "performance and 
> reliability" section
> 
> I don't think I mentioned NENA. My source of the information 
> was the LAPD PSAP (which I visited during the NENA meeting). 
> The person in charge said that their goal was 10s in 95% (not 
> sure about the
> percentage) from call to human answer. They apparently 
> tracked this information. In their case, the concern was 
> primarily human response time, not routing time. Call setup 
> time in mobile systems often approaches several seconds.
> 
> Beyond these anecdotal numbers, I'm not sure that we'll be 
> able to rely on existing performance standards and that we 
> can draw much insight from any number we get, except that 
> having a gnome looking up the information in an atlas is 
> likely to be unsatisfactory and that faster is better.
> 
> I also suspect that the only protocol that would likely fail 
> a reasonable lookup time test, except by pure implementor 
> stupidity, would be one that walked a geo search tree with 
> widely distributed servers for each query.
> 
> 
> Byron Smith wrote:
> > Henning, where do you get the NENA 2s and 10s numbers?  The 
> only thing 
> > I have found in NENA documents is:
> > 
> > "  9 Call Set-up Time
> >      It is recommended that emergency call set-up time not 
> exceed the 
> > average call set-up time for any
> >      other type call made by the customers of that 
> particular serving 
> > office.
> > 
> >      It is also strongly recommended that in all circumstances the 
> > caller hear either audible ring tone or a
> >      recording alerting them that their call is being processed."
> > 
> > The above is from NENA 03-501.   I have looked for other NENA
> > recommendations, but have not found them.
> > 
> > I would appreciate a reference if you have one.
> > 
> > Not that this is terribly relevant: But I would make a small wager 
> > that more than 50% of the (rural) wireline 911 systems in 
> the country 
> > fail to meet the above recommendations.  (Probably closer 
> to 80%) The 
> > observed call setup time for systems that use CAMA trunks 
> is usually 
> > 3-7 seconds dial-to-ring, with 5 seconds being typical. 
> Most digital 
> > end-office switches make local dial-to-ring setups on the 
> order of 1 second.
> > 
> > Byron
> > 
> > 
> > 
> >>-----Original Message-----
> >>From: ecrit-bounces at ietf.org 
> [mailto:ecrit-bounces at ietf.org]On Behalf 
> >>Of Henning Schulzrinne
> >>Sent: Tuesday, August 02, 2005 4:08 AM
> >>To: ecrit at ietf.org
> >>Subject: [Ecrit] Suggestion for "performance and 
> reliability" section
> >>
> >>
> >>I would think capturing the known external requirements as such is 
> >>helpful. For example, the NENA 2s (dial-to-ring) 
> requirement, which is 
> >>part of the 10s dial-to-pick-up I mentioned could just be 
> captured as 
> >>such external guidelines, possibly in a separate "performance and 
> >>reliability" section. If early implementations, with reasonable 
> >>assumptions on round-trip times and topology, can't satisfy 
> those, we 
> >>know we have a problem.
> >>
> >>Henning
> >>
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> > 
> > 
> > 
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