3 or 9 Internet NTP servers?

[Richard L Jackson Jr]

Hi,

I am a newbie to NTP. I am setting up three NTP primary servers, per
DEC/Ultrix recommendation, for George Mason University gmu.edu domain.

Does each primary server have three different Internet NTP servers
as peer or do they use the same. That is, will I be using 9 (3x3)
Internet NTP servers (stratum 1 or 2) or 3?

The DEC documentation says:
"If your site is connected to the Internet, you should configure three
(but no more than three) NTP primary servers at your site that
synchronize to three highly accurate (stratum 1 or stratum 2) hosts on
the Internet."

I may be having a brain fart, but this seems ambiguous. Does
each local NTP primary server use three different Internet servers or
the same three?

BTW, we have several hundred workstations on campus.

Regards,
Richard Jackson
George Mason University

[Rick Thomas]

^% The DEC documentation says:
^% "If your site is connected to the Internet, you should configure three
^% (but no more than three) NTP primary servers at your site that
^% synchronize to three highly accurate (stratum 1 or stratum 2) hosts on
^% the Internet."
^%
^% I may be having a brain fart, but this seems ambiguous. Does
^% each local NTP primary server use three different Internet servers or
^% the same three?

Well, one way of doing it is to have 3 onsite primaries (stratum 3, say)
connected to 4 offsite servers (stratum 2, say) as follows

onsite-1 is client of offsite-a, offsite-b, offsite-c,
and peer to onsite-2, onsite-3
onsite-2 is client of offsite-a, offsite-b, offsite-d,
and peer to onsite-1, onsite-3
onsite-3 is client of offsite-b, offsite-c, offsite-d,
and peer to onsite-1, onsite-2

This spreads your load around and gives you a little extra redundancy, but
not enough to cause severe confusion. Peering onsites with fellow-onsites
makes sure you get consistent time amongst them.

Enjoy!

Rick