Dan, you're awsome !
>> Ah OK, i've looked into it from another point of view. In fact, I was trying >> to be conservative of S1 I'm querying, only one host will query and >> distribute the information to its friends and thus avoiding to have 4 hosts >> on my network querying the same S1 (kinda being the good citizen) >> > It sounds like a good idea when you state it like this, but NTP is naturally > fairly conservative bandwith-wise once it stabilizes. I doubt many public S1 > providers would have a problem with you configuring all 4 hosts. Understood. >> As a matter of fact all my S2 are in the same location. >> So you are saying If I want to keep the infra in sync with itself I should >> do a full mesh of my S2 (each one is poiting to the three others and an S1 >> as a backup) ? >> And if I want tight ref sync I can share some common S1(s) on all my S2 but >> keep a diffrent S1 for evry S2 (diversity) and in that case no need for my >> S2 to be aware of each other ? >> > So, having 4 hosts in the same location is purely so you can have quorum > function properly in your end clients' ntpd setup? Exactly that. Trying to follow the best practices in NTP FAQ basically. Is it overkill ? > If you want the best chance of the best time for the most hosts, you should > let ntpd do what it's best at: monitoring a variety of valid sources and > choosing among the best of them for the best time. Since all your S2 servers > are in one location, they will likely chose among a common S1 population > identically, making them very consistent, but without much diversity. You > want at least a LITTLE diversity if you're using public sources. > Free-like-beer is great until someone has a really bad malfunction on their > time source (see the mailing list from earlier today). If only one of your > stratum2 servers is locked on that bad talker, then your overall > infrastructure will be unaffected as ntpd will identify that time as out of > spec and use one of your other hosts. You can try to get super clever and > tweak things, but I'd start out simple and see how well ntpd does on its own > (usually quite well). I'd start with something like this: > > Sources: > S1-0 = internal GNSS-based source (future?) > S1-1 = public stratum1 that you know is probably good most of the time, e.g. > one of the "navobs" hosts if in the US or a European (or local to you) > equivalent (check with providers' published usage rules). > S1-2 = public stratum1 > S1-3 = public stratum1 > S1-4 = public stratum1 > S1-5 = public stratum1 > S1-6 = public stratum1 > > Your servers: > - S2-1: > - S1-0 > - S1-1 > - S1-2 > - S1-3 > - S2-2: > - S1-0 > - S1-1 > - S1-4 > - S1-5 > - S2-3: > - S1-0 > - S1-1 > - S1-2 > - S1-4 > - S2-4: > - S1-0 > - S1-1 > - S1-3 > - S1-5 > > That will reduce the likelihood that any single upstream having a problem > will trickle-down to your end clients. Once you get your GNSS source up and > running, the 4 S2 hosts will likely use it whenever it's available unless > it's reporting a time that is WAY off. Again, this is just one way it can be > done. You may very well get 99.9 percent of the same performance by any > number of variations with reputable upstream S1s. Just try it out and keep an > eye on the quality of time you're getting and adjust as necessary. Very clear ! Exactly what I had in mind. > Oh and yes, "node" == "service node" == "host providing whatever service > you're talking about". It's terminology common in my technology space. > > -- > Dan _______________________________________________ questions mailing list questions@lists.ntp.org http://lists.ntp.org/listinfo/questions
