Thank you Chuck, I will study the docs in depth tomorrow. They are very much on point for what I am looking for.
With two separate data centers, I am thinking a total of four primaries. Two at each DC, but otherwise similar to the model in your first reference, with no secondaries. My primary goal is reliability, and fault tolerance. I don't need to improve accuracy. >From experimentation, it seems that if all of the primaries loose connectivity >to their sources, they will move to stratum 32. I realize that a GPS clock or >two would be ideal, but I don't think that is going to happen. I think that 4 peered primaries will get us what we need in this case, as each DC has a separate egress to the public network. The DCs support remote offices. I am thinking of configuring the Linux hosts with 3 time servers, the two at the closest DC, and one from the other DC. Mike Edwards > On Sep 3, 2014, at 10:56, Charles Swiger <[email protected]> wrote: > > Hi, Mike-- > >> On May 21, 2014, at 1:38 PM, Mike Edwards <[email protected]> wrote: >> I'm looking for information on best practices to configure ntp for a medium >> sized network. I'm looking for something similar to the whitepapers >> published by Cisco. Cisco outlines several configurations with a mixture >> of peer and server definitions for a set of internal ntp servers. > > Something like: > > http://www.ntp.org/ntpfaq/NTP-s-config-adv.htm > > ...perhaps. There's older docs about "Notes on Configuring NTP and Setting > up a NTP Subnet": > > http://www.eecis.udel.edu/~mills/ntp/html/notes.html > >> Equally useful might be a document that compares the functionality of the >> ntp.org implementation, verses the Cisco ios implementation. Does Cisco >> use the ntp.org code? > > Generally speaking, routers prioritize moving packets around over servicing > traffic sent to the router itself. They tend to make adequate timeservers > for low NTP query rates but exhibit higher latency than dedicated timeservers. > >> I'd like to see a configuration that would be resilient to public server >> failures, and connectivity problems to the public network, as well as >> failures between sites on the internal network. >> >> Do any such documents exist? > > The docs above have some general discussion including multiple internal > datacenters. > > Having a mix of decent external stratum-1 or -2 servers, local timeservers > running > from GPS, ACTS, or other primary timesource, and redundant local S2/S3s that > clients > can talk are all part of obtaining highly resilient time service. > > Note that you can provide world-wide NTP service comparable with large OS > vendors > (ie, time.apple.com, time.windows.com) with a dozen machines broken up into > peer subnets > of 4 boxes in the three major regions. Hardware isn't really the constraint-- > it's dealing with bazillions of tiny packets and being able to throttle > abusive traffic > upstream of your connectivity that matters. > > Regards, > -- > -Chuck > > > _______________________________________________ questions mailing list [email protected] http://lists.ntp.org/listinfo/questions
