[ntp:questions] Re: "Proper" way to test simple, new NTP configuration?

ohaya ohaya at cox.net
Fri May 20 20:05:53 UTC 2005



"Richard B. Gilbert" wrote:
> 
> ohaya wrote:
> 
> >Hi,
> >
> >I'm trying to setup NTP on a small network consisting of all Sun Solaris
> >systems.
> >
> >I'm appending a post that I just made to the Sun admin NG about our
> >configuration, but after doing more reading, I'm wondering if maybe the
> >problem was 'how' we did the test.
> >
> >As mentioned below, to test this, after getting all of the xntpd's up, I
> >simply set the clock back on Solaris1, then watched.  Since making the
> >post, I've found a couple of msgs that seem to indicate that maybe I
> >should have killed the xntpd on Solaris1 (our NTP "server"), then set
> >the time back on that system, then restart the xntpd.
> >
> >Can someone here comment on this?  What is the best (and easiest way) to
> >determine if this simple NTP setup is actually working?
> >
> >Thanks,
> >Jim
> >
> >
> >================= Post about our configuration
> >==========================
> >Hi,
> >
> >I have a very small network consisting of 4 Solaris servers (Solaris1,
> >..., Solaris4) and want to configure NTP so that Solaris2, Solaris3, and
> >Solaris4 synch their time to Solaris1.
> >
> >This is an isolated network (no outside connection available), so from
> >what I've read, I think that Solaris1 should be synched to itself?
> >
> >We tried to set this up yesterday, and got the xnptd running on all 4
> >machines, but when we tested, it didn't seem that anything was happening
> >(we ran snoops on port 123 on several of the machines).
> >
> >We tested by first using ntpdate on Solaris2, 3, and 4 to get them
> >synched to Solaris1, then starting the xnptd on those machines, then
> >setting the system clock on Solaris1 back about 10 minutes, and then
> >watching the snoop output for awhile.
> >
> >Can someone provide what the basic ntp.conf file should look like for
> >Solaris1 and for the other Solaris machines (Solaris2, 3, and 4)?
> >
> >Thanks,
> >
> >
> Don't expect too much from this configuration!!!   A typical,
> undisciplined, computer clock is not a good synchronization source.
> 
> The  machine that keeps the best time by itself; e.g. the clock that
> gains or loses the least amount of time, should be selected as the master.
> 
> On the master, /etc/ntp.conf should contain the statements
> #
> # Declare the local clock to be the clock of last resort.
> # It will be used to serve time in the absence of any other.
> #
> server 127.127.1.0              # Local clock, unit 0
> fudge 127.127.1.0 stratum 10
> 
> On the clients, /etc/ntp.conf  should include:
> server <ip address of server>
> 
> As I said, don't expect too much.   The server will drift and the
> clients will follow it as best they can.  (Imagine following a drunk
> driver!)
> 
> If you want something that both keeps the correct time and keeps tight
> synchronization, get a hardware reference clock for your server.   A GPS
> timing receiver is generally the best choice if you can site the antenna
> where it has an unobstructed view of the sky.  These can generally be
> had for less than $500 US, a lot less if you get the bare bones (naked
> circuit board, wall wart, hockey puck antenna)!  If not, HF receivers
> for WWV, WWVH, CHU, JJY etc can be used.  VLF receivers (WWVB, MSF, or
> DCF77, etc) are also an option.


Richard,

Thanks for the information, esp. the configuration.

FYI, not "expecting much", this configuration is fine for what I am
doing.  The main reason why I wanted to implement this in our test
network is that we are testing some SSO software, which requires that
all the servers be synchronized time-wise within a certain amount of
time.  For this, the absolute time (vs. "the real clock time") is not
important, so this is ok for us.  In our 'real' production environment,
they've already deployed a framework for synching machine times, but up
to now, I was having to manually do the synching in our development
network.

Jim



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