pret3n...@gmail.com wrote:
Yes, circuit switched networks don't have this problem,
for sure.
If, for example, having a GPS on S1, and using it as a
timeserver for X1, and considering the incoming and outgoing
delay on that path are equal, when measuring the OWD
between S1 and X1, I would get a me
Ok, thanks for clearing that up for me. Makes sense :-)
On Saturday, October 27, 2012 8:35:40 PM UTC+1, unruh wrote:
> On 2012-10-27, pret3n...@gmail.com wrote:
>
> > Yes, circuit switched networks don't have this problem,
>
> > for sure.
>
> > If, for example, having a GPS on S1, and using i
On 2012-10-27, pret3n...@gmail.com wrote:
> Yes, circuit switched networks don't have this problem,
> for sure.
> If, for example, having a GPS on S1, and using it as a
> timeserver for X1, and considering the incoming and outgoing
> delay on that path are equal, when measuring the OWD
> between
pret3n...@gmail.com wrote:
Yes, circuit switched networks don't have this problem,
for sure.
If, for example, having a GPS on S1, and using it as a
timeserver for X1, and considering the incoming and outgoing
delay on that path are equal, when measuring the OWD
between S1 and X1, I would get a
Yes, circuit switched networks don't have this problem,
for sure.
If, for example, having a GPS on S1, and using it as a
timeserver for X1, and considering the incoming and outgoing
delay on that path are equal, when measuring the OWD
between S1 and X1, I would get a measurement with an accuracy
On 2012-10-27, pret3n...@gmail.com wrote:
> The accuracy requirement is not written on stone,
> but <1ms would be the goal we're aiming for.
>
> I think you made some confusions on the units
> there (usec and sec, when I think those are in ms),
usec and msec I should have said.
> but I got your
I wrote:
> Then you surely have read Dr. Mills' book.
Pedro writes:
> Unfortunately, I have not, I've only wandered through his website. Can
> you give me a pointer to it?
Mills, David L.
Computer Network Time Synchronization: The Network Time Protocol
Taylor & Francis / CRC Press
ISBN 0-8493-58
The accuracy requirement is not written on stone,
but <1ms would be the goal we're aiming for.
I think you made some confusions on the units
there (usec and sec, when I think those are in ms),
but I got your point. The way NTP works, it estimates
the one-way delays as RTT/2 and uses that to corr
On 2012-10-27, pret3n...@gmail.com wrote:
> Gotcha. There's no hidden agenda though, the purpose
> is to replace an old and proprietary system (QoSMetrics)
> which is being used to measure these OWD's and do monthly
> reports about the quality of the links being measured.
> QoSMetrics used QTP,
Hahah, nice one :-) And yes, I believe the "old" S1 and S2
currently have an external timing source attached to them
(GPS, I think).
So I'll try to use those in the way you mentioned, when we
replace them. Thank you for your input!
On Saturday, October 27, 2012 6:28:33 PM UTC+1, unruh wrote:
>
On 2012-10-27, pret3n...@gmail.com wrote:
> Unfortunately, I have not, I've only wandered through
> his website. Can you give me a pointer to it?
It is mentioned there
But by going to Amazon.com
Computer Network Time Synchronization: The Network Time Protocol on
Earth and in Space, Second Editio
On 2012-10-27, pret3n...@gmail.com wrote:
> OWAMP can refer to One-Way Active Measurement Protocol,
> see http://tools.ietf.org/html/rfc4656, or the tool that follows
> that protocol to measure one-way delay,
> see http://www.internet2.edu/performance/owamp/
>
> NREN, as stated before, means Nati
Unfortunately, I have not, I've only wandered through
his website. Can you give me a pointer to it?
Pedro
On Saturday, October 27, 2012 5:56:42 PM UTC+1, John Hasler wrote:
> pret3nder writes:
>
> > I won't have time to investigate the deeps of NTP, but I do want to
>
> > know the basics, as th
pret3nder writes:
> I won't have time to investigate the deeps of NTP, but I do want to
> know the basics, as that's one of the objectives of my thesis.
Then you surely have read Dr. Mills' book.
--
John Hasler
jhas...@newsguy.com
Dancing Horse Hill
Elmwood, WI USA
_
Gotcha. There's no hidden agenda though, the purpose
is to replace an old and proprietary system (QoSMetrics)
which is being used to measure these OWD's and do monthly
reports about the quality of the links being measured.
QoSMetrics used QTP, a proprietary time protocol.
So, although that is a
pret3n...@gmail.com wrote:
David Woolley is right, the project is about making the measurements,
although I don't like the idea of doing them blindly, without
knowing how to interpret the results. I won't have time to
investigate the deeps of NTP, but I do want to know the basics,
as that's one
OWAMP can refer to One-Way Active Measurement Protocol,
see http://tools.ietf.org/html/rfc4656, or the tool that follows
that protocol to measure one-way delay,
see http://www.internet2.edu/performance/owamp/
NREN, as stated before, means National Research and Education Network.
@unruh: yes, I w
On 2012-10-27, pret3n...@gmail.com wrote:
> Hello all, and thank you again for your valuable insight
> on this matter, it's been a great help to me.
> I'll now try to reply to all your comments, please excuse
> me if I missed a particular comment.
>
> Indeed I was wrong about the tunnel referenc
On 10/26/2012 6:47 PM, pret3n...@gmail.com wrote:
I'm sorry, I'm not following you. What delay asymmetry are you refering to?
OWAMP does rely on accurate time stamps, see
http://www.internet2.edu/performance/owamp/index.html
If I have S1 and X1 synching to the same time reference (in this case
On 10/26/2012 5:56 PM, pret3n...@gmail.com wrote:
Hi all, and thank you for your answers. I'm afraid I might not have
been clear about my objectives, so I'll try to explain clearer.
I'll also try and keep the lines smaller, and please, excuse me if
I make any mistakes, as english is not my native
Hello all, and thank you again for your valuable insight
on this matter, it's been a great help to me.
I'll now try to reply to all your comments, please excuse
me if I missed a particular comment.
Indeed I was wrong about the tunnel reference, that won't
correct the fact that a delay asymmetry
Terje Mathisen writes:
> The crux is this: You _MUST_ have a path to an absolute time
> reference, at both ends, which is totally independent of the path you
> are trying to measure!
And a tunnel is _not_ an independent path.
--
John Hasler
jhas...@newsguy.com
Dancing Horse Hill
Elmwood, WI USA
pret3n...@gmail.com wrote:
An NREN is a National Research and Education Network.
We are talking about 26 servers spread all over the country
and in the islands, so your figures are a bit off, I'm afraid. $50
don't cover the expenses associated with getting a GPS for every
single server, and like
unruh wrote:
Then after a few days of running, plot the offset against the delay, and
look at that graph. You may well notice wings on that graph with slope
of 1/2 . Those are
asymmetric delays. The spread of the central blob will also give you an
idea of the noise on your connection.
Essen
On Sat, 27 Oct 2012 02:40:30 GMT, Kennedy, Paul wrote:
>
>
> Pk>>By controlling which refclocks the various test sites use, you
> should see they synch up well enough. We do this regularly. Unruh makes
> a very good point on the delay Vs Offset. You should certainly be doing
> this as it will rev
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