ben slimup wrote:
Thank for prompt answer Chris,
Unfortunately, this ntp network should give time to specific clients
devices and not anyone on the public network.
according to your advice, better not using load balancer, thats good
how to load balance between ntp server if i do not use round robin?
if all client choosing the same server then the ntp server will be
overload. is it a problem if for example client 1 poll or synch with
server 1 , and then with server 2 , etc...? or udp roundtrip comes
each time from different ntp server? how many ntp servers should be
needed to handle that much request knowing that each card handle
10,000 request per sec?
First, each client should have at least 4 configured servers, so you can
use the same ntp.conf file for all of them.
Second, if you really can handle 10K requests/second per card, then that
means that you can handle 640K clients per card, with worst-case polling.
I.e. servers capable of 10K/second should handle your expected load just
fine, even though a proper (FreeBSD-based) 1U server with a GPS will
serve even more clients with better time performance.
Terje
much appreciate your expertize
cheers
From: [email protected] Date: Wed, 21 Dec 2011 19:43:53
-0800 Subject: Re: [ntp:questions] ntp server pool advice To:
[email protected]
On Wed, Dec 21, 2011 at 5:07 PM, ben slimup<[email protected]>
wrote:
Dear all,
Thank you very much for support,
i do not have 1000,000 client, i need those ntp servers to serve
a load between 100000 to 1000000 clients over a public network
with an accuracy of 100ms
those clients will use dns round robin to resolve 4 external ip,
2 IPs on each site. i have 4 servers with 4 ntp server slot card
each ( meinberg M900) 1 ntp server card can support 10,000
request.
First off the good news. 100ms is an "easy" spec to meet you can
do this without a lot of effort.
Don't let the outside world "see" your meinberg servers. Build
out a layer of "statum 2" servers and expose those to your clients.
1M clients is a lot for the little 386 class CPU that is in the
meinberg box.
I still don't understand, Why do all those NTP clients need to go
to your NTP servers. Why can't they use any they like? Are your
servers doing something special?
Also know that EACH client needs to be configured to see multiple
NTP servers. practically three servers is a minimum but others
will argue for more for five
A would not use load balancing for NTP servers. With NTP it
does not matter at all if a server crashes. The clients are all
configure to use five servers and if one crashes they will do fine
using four. If you expose four, large robust servers one on each of
your four IP addresses then you will be fine, even if one fails you
will be fine. The clients will notice the failure and continue on
using the remaining three.
I technical question for the list: Would Round Robin load
balancing even work. I think it would introduce so much jitter the
server would be usless. I think you have to be sure that each
time a client pools a server at a given IP address it polls the
same physical server.
Chris Albertson Redondo Beach, California
--
- <Terje.Mathisen at tmsw.no>
"almost all programming can be viewed as an exercise in caching"
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