[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

Re: Any good time servers around?




On Fri, 1 Aug 1997, Ira Abramov wrote:

> On Fri, 1 Aug 1997, Rafi Sadowsky wrote:
> 
> > Amos,
> > suprised that you suggest syncing to two stratum 1 servers
> > (relay.huj.ac.il - should be refferered to as ntp.ac.il BTW
> >  & ntp.psi.net )
> > for a home computer - to preventexcess load on stratum 1 servers
> 
> who is the top server then, the most accurate one? isn't there some cesium
> clock in Weizmann that we can all sync to?
Ira you missed the point - ntp.ac.il is at the Hebrew University ( Givat
Ram I think ) - it is synced to an atimic clock - with backup to other
stratum 1 servers overseas  - one time sync ( such as ntpdate ) may be
appropriate - but sinc NTP is a heirarchial system
(& still freindly + free in the for now .. )
the convention is that only servers with a sizabale network behind them
sync to stratum one servers
( it also acceptesdd to use redundancy - that is if you have 2 stratum 2
servers for a network - you would sync them to differnet set's of stratum1
servers for reliablility )
unless you need very hig accuracy ( < 1/10 second say ) syncing to a group
of stratum2 ( or even stratum 3 which are synced to 2 ) servers will do
just fine thank - you -as a matter of fact network delays 
it is howevr polite ( and sometime mandated by access lists ) to ask the
maintainer of the ntp server for permission to sync to his clock

it is ridiculous for each home user in israel to sync to ntp.ac.il
(which is an alias for the same machoine as ns.il - the master DNS for .il
& most second level doamins under it )
as this will create a rather large load & probably cuase it to become an
unreliable time source :-(
this will of course neccitate it's maintener to put on an ACL that woin't
even allow one time syncing ( ntpdate )

a list of publicly availible NTP clock  sources can be found at
(+ a discussion of who to sync to ) can be found at
 http://www.eecis.udel.edu/~mills/ntp/servers.htm

as an aside - i haven't check if ther ar any israeli server there
- please note that notviosin connectivity ( via IIX ) to non-netvion
customers in Israel ( including MACHBA - universities suffer )
from delays that make the link rather unsitablr for NTP

if you want you may sync to ntp[12].openu.ac.il
(until I see a load problem in which ccase I may cut off public access  -
*without* notice ) - please use DNS rather than the IP addresses as the
hosts may change ...

P.S. there was an Israeli NTP admin list which AmoSs starded when he was
at HUJI (yes quite a while ago ) - but it's benn dead for quite a while

hopefully his will help - I really think that large ISP'S ( Netvision
Internet Gold, UBM , whoever ) should supply reliable NTP service )
of course if customer don't ask for it they won't supply it as it cost
money ( staff time, machine , possibly a Radio/Atom clock )

if you don't ask for it - you defintly won't get it ...

I rest my case for now ...

-- 
Rafi Sadowsky                                   rafi@oumail.openu.ac.il
[postmaster@openu.ac.il]  VoiceMail: +972-3-646-0592   FAX: +972-3-646-5410
Network Architect         |            ILAN-CERT(CERT-L@VM.TAU.AC.IL)
Open University of Israel |     (PGP key availble by finger or key servers) 



>    -------------------------------------------------------------
>    Ira Abramov          <ira@scso.com>        Scalable Solutions
>    POBox 3600, Jerusalem 91035, Israel       Tel (972)2-642-6822
>    http://www.scso.com/~ira   Check out: http://www.linux.org.il
> 
> 

-- 
Rafi Sadowsky                                   rafi@oumail.openu.ac.il
[postmaster@openu.ac.il]  VoiceMail: +972-3-646-0592   FAX: +972-3-646-5410
Network Architect         |            ILAN-CERT(CERT-L@VM.TAU.AC.IL)
Open University of Israel |     (PGP key availble by finger or key servers) 
]


References: