On Thu, Jul 4, 2019 at 4:51 PM Jason Rabel <jasonrabe...@gmail.com> wrote: > > You never mentioned what your "clients" are going to be using? Are > they running NTP too and will be able to choose multiple sources, or > are they basically SNTP clients requesting time from only one server?
Mostly servers/hosts running NTP or Chrony services. But also network devices (switchs routers) that probably will use some sort of and SNTP client > As someone else said, using 'peer' really isn't useful or necessary > *unless* your connection is flaky and expect the S2 servers will need > to free-run, or you are trying to keep consistent time across multiple > locations. Also the server(s) will only drop to S3 *if* the S1 sources > become a worse source of time. 'Peer' doesn't take priority over > 'Server', it all depends on who has the time with the least amount of > uncertainty. I see clearly now the intended behaviour with the peer directive. > > Do you think that I should be using the same 4 upstream NTP stratum 1 > > servers on all my stratum 2 servers? My failure scenario is if one of > > those upstream is faulty, my pool detect it and everything continues > > to work (and if my Internet connection is dead, I have more bigger > > problems than NTP going out of sync) > > No! You want diversity for each of your servers! Even though you are > using multiple upstream servers, it is still best to "spread out the > risk"... Technically 3 servers would be the bare minimum (which > provides no redundancy), however generally you want no less than 4 and > no more than 7 servers. I personally try to stay towards the upper end > if at all possible (but I do not choose all stratum 1's). I've gone with Dan's suggestion 2 S1 common to all S2 and have every S2 have 2 more different S1s > The general rule is for 2n+1 to protect against "n" falsetickers. So > with 4 upstream servers, you are really only protected against 1 bad > server. However, with 5 upstream, then you are protected against 2 > falsetickers, and so on... > > Do not feel like you *must* choose all S1 servers for your primary NTP > servers. S2, and even a S3 is okay to have in your mix *if* they all > reasonably agree on the time. The only caveat is you wouldn't want a > S2 server to be using the same S1 server as you already have in your > list. > > Finally, if you haven't already checked, 'time.apple.com' has been a > good time source (for my servers at least). On the other hand > 'time.cloudflare.com' was showing a constant 2ms offset from the rest > of the group. I'll take a look. time.apple.com is already used by Apple devices anyway. Youssef _______________________________________________ questions mailing list questions@lists.ntp.org http://lists.ntp.org/listinfo/questions
