[ntp:questions] Re: ntp.conf For Clients

Danny Mayer mayer at gis.net
Wed Jun 22 03:15:42 UTC 2005


David Woolley wrote:
> In article <mailman.104.1119362028.91305.questions at lists.ntp.isc.org>,
> Stewart Pelegan <spelegan at csc.com> wrote:
> 
> 
>>Right now, I've got the following in the clients' ntp.conf:
> 
> 
>>broadcastclient
>>multicastclient 224.0.1.1
> 
> 
> It's not very sensible to have both.  You should get things working
> properly without multi/broad-cast before you add this complication.
> 
Actually there's nothing wrong with this if they are coming from
different places. I wouldn't do it if initially setting up.
> 
>>enable auth monitor
> 
> 
> I'm not an expert on auth, but you should not have it, initially,
> when debugging without broadcast.   I think it may be needed for
> broadcast modes.  I cannot see any indication of the key files
> that it must need.
> 
broadcast and multicast have auth enabled by default.  I'd turn it
off initially when starting a configuration. However your server
is not sending broadcast packets. Are you getting them from
elsewhere?

> 
>>and the servers have:
> 
> 
>>server 127.127.5.0 prefer
>>server 10.20.30.41
>>server 127.127.1.0

Add iburst to get things set up quickly.

>>fudge 10.20.30.41 stratum 1
> 
> 
> The stratum 1 here will be ineffective.
> 
> 
>>fudge 127.127.1.0 stratum 1
> 
> 
> Setting a local clock to stratum one is not something you want to
> do lightly.  I can see no valid reason for doing it here.  I am pretty
> sure that having this local clock will make the configuration unstable
> when the radio clocks fail.  The only time to have one at stratum one
> is if the local clock is being disciplined by something other than ntpd,
> and even then there is the problem that ntpd will not know if that
> source has failed.
> 
> 
>>broadcast 224.0.1.1 ttl 6
> 
> 
> ttl 6 is too large if all the clients are on the same sub-net.  Simple
> broadcast would be enough.
> 
The ttl is in fact a hop count. You are unlikely to need more than a ttl 
of 2 and you certainly shouldn't propogate more than you need. You are
better leaving it at the default.

Danny



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