[time-nuts] Google NTP Servers and smearing leap seconds...

Tom Holmes tholmes at woh.rr.com
Sat Sep 17 01:25:46 UTC 2011


All this fuss over microseconds being worth billions and it still takes a
bank 5 days to find out if the check I wrote is good?

Where's a good manure scoop when you need one?

Tom Holmes, N8ZM
Tipp City, OH
EM79

> -----Original Message-----
> From: time-nuts-bounces at febo.com [mailto:time-nuts-bounces at febo.com] On
> Behalf Of Bob Paddock
> Sent: Friday, September 16, 2011 7:50 PM
> To: Discussion of precise time and frequency measurement
> Subject: Re: [time-nuts] Google NTP Servers and smearing leap seconds...
> 
> On Fri, Sep 16, 2011 at 2:36 PM, Hal Murray <hmurray at megapathdsl.net>
> wrote:
> >
> > xaos at darksmile.net said:
> >> You can forget Wall St. firms and Banks for starters.
> >
> >> They need sub-microsecond accurate timing as some instruments (Forex)
> are
> >> moving to <10 microsecond latency from order entry to order ack.
> >
> > 10 microsecond latency doesn't say anything about how accurate the time
has
> > to be.
> >
> > Does anybody have a good URL on the accuracy requirements of banks
and/or
> > stock markets?  I expect there are both legal and technical issues.  I'd
like
> > to understand them separately
> 
> There are some big names in Banking and Stocks behind the
>  Advanced Message Queuing Protocol (AMQP):
> 
> http://www.amqp.org/confluence/display/AMQP/About+AMQP
> 
> http://www.oasis-open.org/committees/tc_home.php?wg_abbrev=amqp
> 
> http://amqp.org/resources/financial-services
> 
> Actually Time Nut Grade measurements are not addressed at this level
> to my knowledge.
> 
>       <p><b>Round Trip</b>: The term round trip refers to the
>       process of a peer sending a command to its partner and
>       receiving confirmation that the command is complete. Round
>       trips are necessary for synchronization of world views,
>       however, it is not necessary for a client to wait and do
>       nothing while a round trip occurs or only deal with a single
>       round trip at a time.</p>
>     </li>
> 
>     <li>
>       <p><b>Round Trip Time (RTT)</b>: The term RTT refers to the
>       time taken to complete a round trip. This is described with
>       the following formula:</p>
>       <pre>
> RTT = 2*latency_network + latency_processing
> </pre>
> 
>       <p>Note that RTT at the execution layer differs from RTT at
>       the network layer. At the network layer the processing
>       latency is zero resulting in an RTT of twice the network
>       latency. At the execution layer the processing time becomes
>       significant if, for example, processing the command requires
>       sending data to disk. This would be the case with durable
>       messages and the RTT would then include the Broker's disk
>       latency.</p>
>     </li>
> 
> > but I won't be surprised if they are thoroughly
> > tangled.
> 
> http://www.imatix.com/articles:whats-wrong-with-amqp
> 
> There is also the even more obscure 0MQ:
> 
> http://www.zeromq.org/
> 
> 
> 
> 
> --
> http://blog.softwaresafety.net/
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> http://www.wearablesmartsensors.com/
> 
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