[ntp:questions] Dimensioning NTP Server

Luis Colorado luis.colorado at hispalinux.es
Sun Dec 23 23:08:31 UTC 2007


"Aggarwal Vivek-Q4997C" <Q4997C at motorola.com> escribió en el mensaje news:750BBC72E178114F9DC4872EBFF29A5B05217A23 at ZMY16EXM66.ds.mot.com...
> Hi
> Iam planning to have NTP Server for something around 50,000 Clients in
> the Network

If you are being to deploy NTP to 50,000 clients, perhaps you'd better to put your routers (sure you don't have only one) or your DHCP servers to proxy NTP for them.  You don't have to use just one NTP server, you can get several in synch so time is distributed with not so much network load.

In doing so you'll get several advantages:

* You'll get less network load, as NTP traffic don't pass over the local net.  NTP is very sensible to network load.  Time offsets get greater in loaded network.  NTP proxies can use their clocks to stabilize time offsets due to network load.

* You'll get less synch delay.  People tends to think that using only one server will get all clients synched with it, but you'll get a couple of 50,000 pcs with different times, because of network load at time servers. NTP gets better results in a low loaded net.  Time exactitude depends on two factors: network load introduces noise in time measurements, leading to greater time offsets from the source of time.  Network NTP hops introduces a constant (or nearly constant) latency from the source of time, but this latencies are taken into account when synchronizing and you'll have better results using more levels of deploying time than making everything point to a master server.

* You'll get more exact times if you balance the levels of stratumness with the number of clients that will ask a single server.  I think a good starting balance is making all routers take time from your master server (better two or three servers for all the routers to get fault tolerance) and then the final clients to ask the routers for time. If you are considering to join 50,000 network nodes in a network, you'll be able to select routers capable of acting as timeservers for the localnet.

> 
> Can Anyone guide me in dimensioning the NTP Server. What are the
> guidelines that I should take care for dimensioning the NTP Server
> 
> Also can I two NTP Servers running in active-stand by or in Load
> balancing scenario in the same network

You can use better several NTP servers, and point routers to them all.  NTP is designed with fault tolerance in mind, even to get better clock timeline.

> 
> Regards
> Vivek Aggarwal




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