I use minpoll 4 maxpoll 5 on the client that accesses external servers and minpoll 4 maxpoll 4 on the LAN. The results justify the means: consistent sub-100 millisecond offsets on the LAN (presently -0.011 on this computer). The only time I have been knocked off an NIST server was when I switched from one computer to another as the external gateway. Because of the NAT, time-d and time-d.nist.gov picked up the fast request rate right away when both clients were briefly active, and would not let me back on for a day or so.
Charles Elliott > -----Original Message----- > From: questions [mailto:questions- > bounces+elliott.ch=comcast....@lists.ntp.org] On Behalf Of Charles > Swiger > Sent: Sunday, August 2, 2015 10:34 AM > To: Mike Cook > Cc: Questions List > Subject: Re: [ntp:questions] iburst and NIST servers > > On Aug 2, 2015, at 2:31 AM, Mike Cook <michael.c...@sfr.fr> wrote: > > Can anyone confirm that this is an issue? > > > > I habitually put an burst directive in my ntp.conf server statements. > ex: > > > > server 129.6.15.30 noselect iburst minpoll 4 maxpoll 6 > > server 128.138.140.44 noselect iburst minpoll 4 maxpoll 6 > > server 98.175.203.200 noselect iburst minpoll 4 maxpoll 6 > > > > But in the case of these NIST servers, sometimes they never get out > of INIT state. > > iburst isn't usually a problem, but minpoll 4 / maxpoll 6 would be > considered abusive without prior arrangements. minpoll 6 is the > fastest > rate you should query other NTP servers without explicit permission. > > To be more specific, folks who implement per-client firewall rate rules > tend to block clients who exceed ~100 packets per hour. > > > The main point of iburst is to quickly get a downed NTP server back up > and serving valid time. That matters most for isolated stratum-2+ > servers; if you've already got S1 timesources available and multiple > redundant NTP servers locally, using iburst is superfluous. > > Sure, use iburst on one remote server entry if you want and/or against > all of the other NTP peers on your local subnet, but it's not obviously > helpful to use iburst everywhere. > > Regards, > -- > -Chuck > > _______________________________________________ > questions mailing list > questions@lists.ntp.org > http://lists.ntp.org/listinfo/questions _______________________________________________ questions mailing list questions@lists.ntp.org http://lists.ntp.org/listinfo/questions
