ben slimup wrote:
Dear all,
i m currently working on some project that needs a particular ntp
distribution design:
i have to site with 4 public ip address, that can be used on both
site, i need to serve between 100000 client to 1 million.. load
balanced either on 1 site or both. i have on each site 2 box with 4
ntp server (slot card) that can deliver synchronize 10,000client per
card i can also use a L4 load balancer on each site if required, also
dns round robin
i would like to know how can i design a proper ntp network with
redundancy on both site that can handle such client request.
1) Forget about those black box ntp implementations, just use them for
an S1 layer with no direct usage by those 100K to 1M clients.
2) Setup 2 FreeBSD-based servers at each site, all four connecting to
all the S1 servers and to each other. This will be your 4 S2 servers.
3) Configure all clients to talk to all 4 S2 servers.
4) Make sure that the S2 servers have sufficient network bandwidth (just
give them a dedicated Gbit port each, even though they won't need it!)
The worst-case load on each S2 server, with every client running at the
default minimum 64-second poll interval, will be 1M ntp requests every
64 seconds, or about 16 K packets/seconds, corresponding to about 10
Mbit/s of full duplex traffic.
If we also use iburst in order to speedup initial sync time, we get less
than 10 times this, so still well below 100 Mbit/s, something a modern
x86 server will handle easily.
In real life each client will pretty quickly ramp down the polling rate,
probably averaging ~512 seconds/poll or so, reducing the server load by
nearly an order of magnitude, but still too much for your ntp server cards.
Finally, if you must have S1 level performance from each of your
servers, I suggest hooking a SURE or Garmin gps to each of them!
Terje
PS. If you want even more hand-holding I'm available for consulting
work, and so are several others of the regulars here. :-)
--
- <Terje.Mathisen at tmsw.no>
"almost all programming can be viewed as an exercise in caching"
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