Richard Bosire wrote:
>
> Hie
>
> There are # of public NTP servers .
> You can get pointers from here
>
> http://www.eecis.udel.edu/~mills/ntp/servers.htm
>
> bosire
>
> Cjack wrote:
>
> > I want to config a network that consist about 17 routers. But i dont
have a
> > atomic clock
Take your best router, like a 7500 with a real calendar, and synchronize
it to several external stratum 1 servers and perhaps a coupld of
sttratum 2 servers as a backup. This will usually work, but often
results in a great deal of variance (NTP calls it "dispersion") over
time due to variancein propagation delay. If you want to border on
being rude, synchronize two of them to external sources. But at best
you will get stratum 2. Then have everything internal synchronize to
your source(s). They will be very accurte stratum 3 servers (variance
from your reference clock will be minimal). It isn't polite "etiquette"
to sync too many routers to external sources, so get yourself one, or at
most two, good internal references. We use a 7505, which has an
internal calendar, and the 'ntp update-calendar' keeps the date correct
as well (some routers have no clue, that's why they default to reporting
time as elapsed time since it last booted).
I've not tried to setup broadcast servers or peers, but just settle for
setting 'ntp server aaa.bbb.ccc.ddd' pointing to my really sunchronized
router, or maybe add 'ntp server eee.fff.ggg.hhh' to point to the
secondary. No playing with broadcasts, peers, and the like.
Works quire well, and we are within few milliseconds of real time, which
is close enough for me.
Jeff
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