[ntp:questions] ntp architecture

Terje Mathisen "terje.mathisen at tmsw.no" at ntp.org
Tue Oct 26 08:27:26 UTC 2010

konsu wrote:
> On Oct 25, 4:13 pm, unruh<un... at wormhole.physics.ubc.ca>  wrote:
>>> Are there any guidelines about best practices and if an architecture
>>> like this would look good ? Then the intention is that all Linux/UNIX
>>> servers would sync time to the stratum 2 clocks {3 in total}. If
>>> possible can someone give me examples of config files for each of the
>>> 3 stratum 2 servers ?
>> Why not just have all reference the GPS source? How many clients are
>> there?
> Hi, thanks for the reply..........................
> Indeed the appliance is a Meinberg LANTIME M300/GPS which has an
> inbuilt GPS clock and provides an ntp daemon { I am sure it is BSD or
> linux inside}. since we will have over 400 clients I preferred to use
> a layered approach and doing a stratum 2 layer seems easy and elegant.
> As you say I am now thinking what happens if the appliances fails , I
> can either have a procedure to switch to ntp pool project {only as a
> disaster scenario until replacement} or else I have the option that
> our datacentre supplier offered a DCF77 signal to which I can also buy
> another appliance so effectively I would have two stratum 0 and
> stratum 1 sources but as far as I understand 2 servers as sources
> should never be used so I don't know if if I should stick to one
> source and if it fails I failover to the other system {radio or ntp
> pool project only for disaster}

With a black box server I agree that you should setup a number of 
secondary servers, simply because I haven't seen a single such appliance 
that hasn't failed at least once, and overload is one of the failure 

Your 3 (or even better 4) secondary servers should all use ntp.conf 
files similar to this:

# Config for ntp1.mydomain server
server x.y.z.n minpoll 4 maxpoll 4 iburst prefer # Meinberg
server 1.CC.pool.ntp.org	# CC is your country code,
server 2.CC.pool.ntp.org	# this gives you three independent
server 3.CC.pool.ntp.org	# and relatively close servers

and all the clients will then use

server ntp1.mydomain
server ntp2.mydomain
server ntp3.mydomain
server ntp4.mydomain

Adding restrict can wait until the basic setup works, some monitoring 
options can be nice in order to figure out how well it is working.

- <Terje.Mathisen at tmsw.no>
"almost all programming can be viewed as an exercise in caching"

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