Network Latency Measurements

Jim Gettys jg at freedesktop.org
Wed Dec 5 15:16:41 UTC 2012


On Tue, Dec 4, 2012 at 4:05 PM, Tal Mizrahi <talmi at marvell.com> wrote:

> Hi,
>
> We are looking for publicly available statistics of network latency
> measurements taken in large networks.
> For example, there is FCC's measurements (
> http://www.fcc.gov/measuring-broadband-america/2012/july
>
> ).
> However, we are looking for something more detailed that can show a large
> number of latency measurements taken periodically (preferably with as small
> a period as possible).
>
> Here are the datasets I'm aware of:

ICSI Netalyzr
The FCC measurements
MLabs http://www.measurementlab.net/


None of them, to my knowledge, take latency measurements "periodically".

I watched a nice demo at a talk about Mlabs a couple weeks ago of the
ability to query their data set and plot the results.  They happened to
plot a million or so latency samples (and they have when those samples were
taken).

Just don't throw out the "can't possibly happen" outliers; bufferbloat is
bad enough (if you look at the Netalyzr scatterplots you can find here
http://gettys.wordpress.com/2010/12/06/whose-house-is-of-glasse-must-not-throw-stones-at-another/
you'll
see why...).  Unfortunately, latencies measured in *seconds* are not only
possible, but not uncommon (e.g. my brother's DSL service has > 3 seconds
of buffering in each direction under load).

                         - Jim


More information about the NANOG mailing list