[ntp:questions] Re: Which public servers for adjustment?

Helmut Wollmersdorfer helmut at wollmersdorfer.at
Tue Dec 21 12:54:00 UTC 2004


Barry Bouwsma wrote:
> Serwoas!

Grias Di!

> See my headers, then add the propagation delay via NNTP to your
> site! 

LOL.

> Hmmm, what sort of network connection do you have?  And how loaded
> is it?

Broadband Cable, 512 Kbit up, 1024 down. Its not overloaded. Large 
downloads perform mostly stable at the maximum. The problem is the large 
number of hops in the network of my provider. In Vienna traffic is 
exchanged centrally at VIX www.vix.at, where most providers and large 
organisations house their routers. Alternative international or overseas 
routes may exist. I have 7 hops to VIX with ping
rtt min/avg/max/mdev = 6.993/10.688/19.057/3.441 ms

> I suspect your other server is 192.168... given its closeness, 

Exactly. Closer would be possible by use of the direct cluster link, but 
this can have heavy traffic of DRBD-mirroring.

> I'd hope to see other references that are not so far away as the
> ca. 15msec to what appear to be austrian sites.  

Thanks your hints I found some additional servers at universities.
Around 10msec will be the best what I can get.

> Further, the jitter
> given by those nearby sites is pretty bad, suggesting you see a lot
> of traffic on your link which is probably relatively slow to start
> with anyway.

Unfortunately timeserver culture seems to be low in Austria.
I know that caesium or rubidium standards are used e.g. at
- orf.at synchronizing to eurovison members
- telekom.at in each telephone switch
- technical and scientific universities
- metrologie.at
But they are used for technical or scientific purposes with no 
connection to IT/internet departements.

In case of metrologie.at the problem is low budget from the government.
 From a friend I know, that they wanted to set up a broadcast system for 
very high accuracy dGPS, but did not get the few Mio. EUR.
Providing stratum 14 by a weak connection is very poor for a metrologie 
institution.

Universities and providers peer to each other or to the well known 
international servers. Public servers got fewer in the last two years.

> For what it's worth, I can't get an `ntpq' report from your EUnet
> peer, but from here, it claims to be 20msec off from my machine.

Copied from my old confs. They had good quality, but financial problems, 
good staff left.

> Your ORF/APA peer shows up here as 10msec off.  

Good connection, but site with with the most consumer traffic causing 
temporarely high loads.

> You might want to poke Uni-Wien --
[...]
>  ns3.univie.ac.a ns4.univie.ac.a  3 u  228 1024  377    0.462    0.202   0.025
>  tunamea.tuwien. 0.0.0.0         16 u    - 1024    0    0.000    0.000 4000.00
> -tunameb.tuwien. tunamea.tuwien.  2 u  596 1024  377    1.469    2.288   0.924
> -uhura.kom.tuwie ntp1.ptb.de      2 u  453 1024  376    6.855   -3.163   1.065

Good example for the history of public timeservers in .at. One year ago 
I had nice results with tuwien, univie and eunet. Now tuwien is not 
reachable, only one at a time of univie, and eunet became bad.

> Try that -- or poke a closer university or ISP.  

VIX is the central point, with a distance of 7 hops, pingtime ~9ms.

> For example, if you
> were to be in the west of austria, you could try ns.tele.net, 

They are at VIX too, but with a bottleneck at hop 10, pingtime ~25ms 
which is nearly the same as to their timeserver.

> This shows two GPS peers of interest, both of which show here as well
> under 1msec off -- CESnet and tt126.RIPE.  Check your paths to them --
> you may have a fast direct path via Wien to Praha and CESnet.

tt126.ripe is directly connected to tele.net with hop distance of 12, 
thus ~25ms.

cesnet - got the hit. Own route of my provider and direct connection of 
cesnet. 10 hops, ~15ms.

thx.

Helmut Wollmersdorfer



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