> -----Mensagem original----- > De Nuno Pereira Em nome de Brian Inglis > Enviada: sábado, 21 de Fevereiro de 2015 01:43 > Para: [email protected] > Assunto: Re: [ntp:questions] NTP with 2 servers > > On 2015-02-20 16:58, William Unruh wrote: > > On 2015-02-20, Nuno Pereira wrote: > >> In our infrastructure we had some ntp clients that don't have access to the > >> world and so they are configured to use only 2 servers (by the way, the > other > >> have 2 more options). In reality both servers are the same, but with > different > >> IPs. > > So you only have one server. Why have two that are the same? > >> From time to time some clients configured in this way lose their reference > for > >> some short period. > >> I know how NTP works > >> (http://www.ntp.org/ntpfaq/NTP-s-algo-real.htm#Q-NTP-ALGO), and so > this seems > >> to be caused by both 2 servers or just 1 of them not have survived. > >> But both the clients and the servers are physically in the same place, and > >> even if they aren't in the same IP network, they are in the same LAN with > just > >> a switch or two between them (delay is between 1 and 2 ms). > > What is the switch? Smoke signals? Any switch should be a lot lot faster > > than 1ms. > >> And the question is why this does happen in the local network? > >> Aren't they close enough in order to avoid a split? > >> Given that, I have changed the configuration, and now they only use 1 > server, > >> but that is not a good solution. > > But that is what you have! > >> Any alternative for the configuration? More servers, most likely virtual > >> servers? > > I dislike the term servers here and prefer sources, as what you need are > 3-5 independent sources of time. You can get that by setting up NTP on > some other Internet facing physical servers (Windows, Linux, BSD) whose > CPUs and network I/O are not overloaded, using pool and/or separate, > local, independent sources, and have all your internal clients configured > to sync from all of those internal sources. > Take care. Thanks, Brian Inglis Thank you for your interesting answer. The clients where I have configured just 2 sources (1, in reality) aren't facing the internet, and so can only use local servers. That can be changed, but we would prefer to use local servers. Getting those " some other Internet facing physical servers (Windows, Linux, BSD) whose CPUs and network I/O are not overloaded" is our problem: we just don't seem to find them: either our servers aren't, as you say, facing the internet, or aren't with the CPUs or network I/O overloaded (actually I/O in general, not network I/O), or may not be.
> You will have to roll patchings across your internal time sources with > delays to ensure that no more than one source is out of sync at any time. What do you mean by that? Nuno Pereira G9Telecom _______________________________________________ questions mailing list [email protected] http://lists.ntp.org/listinfo/questions
