[ntp:questions] [help]how to configure ntp in a private network and without extra refer clock source?

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Mon Jul 14 17:51:24 UTC 2014


john.wang.wjq at gmail.com wrote:
> I'm trying to do the same thing in an isolated network,
>  except that me have around 60 kvm nodes running on 20
>  physical Linux boxes.
> Out of them I'm trying to use 3 or 4 boxes as my NTP
>  servers to form a HA time service.
>> now, I need to configure ntp  server and client  in a private network environment, supposed that:
>>                     |------  client D
>> Server A     |------  client E
>> Server B     | ------ client F
>>                     |------  clientG
>> servers and clients are all  linux  physical machine.
>> I want  those clients  is synchonized to Server A  or Server B ,
>> Both A and B are using Local clock in their mainboard,
>>  without  extra refer clock source.

Unless those have been upgradedwith a much better than typical oscillator,
  {At least a OCXO, if not derived from a rubidium or cesium frequency source};
 they are going to drift away from UTC in a short amount of time;
  {A GPS with PPS, or internet time sources available to A / B would cure that}.


>> why use two Servers ? I want to implemet ntp server HA :when A  became down,
>>  clients can  be synchonized to B .
>> A’s ip : 192.168.1.10
>> B’s ip : 192.168.1.20
>> So I configure  ntp.conf
>> on A  :
>> server 127.127.1.0

Don't do that.


>> fudge  127.127.1.0 stratum 11
>> on B:
>> server 127.127.1.0

Don't do that.


>> fudge 127.127.1.0 stratum 11
>> on all clients , such as D:
>> server  192.168.1.10
>> server  192.168.1.20
>> but I “ntpq �p” on D :
>> remote           refid    st t when poll reach delay   offset   jitter
>> ==============================================================================
>> x192.168.227.142 LOCAL(0) 11 u    2   64   377 0.274    61.575  24.412
>> x192.168.227.148 LOCAL(0) 11 u   39   64   377 0.187  1820.54   23.696
>> My expect is that : there is at least  a   asterisk “*” in two line, now both is “x” ,
>> My question:
>> 1.I think  client  can’t be sysynchonized to Server A or Server B,  this opinion Is  right ?
>> 2.If  want to  appear  asterisk  , how will  I do ?

Yes, they have no common reference, so they drifted away from each other;
 (and likely normal / typical / consumer / business PC crystals / oscillators).



# Start ntpd with -g, the -g will prevent a panic stop if the time needs to be stepped when started
# ntp.conf for ALL (Clients and/or Servers)
restrict -4 default limited kod nomodify notrap nopeer noquery
restrict 127.0.0.1
restrict -6 default limited kod nomodify notrap nopeer noquery
restrict ::1
restrict 224.0.1.1 mask 255.255.255.255 nomodify
restrict 192.168.1.0  mask 255.255.255.0 nomodify
restrict 192.168.227.0  mask 255.255.255.0 nomodify
restrict source nomodify
tos cohort 1 orphan 11
keys "/etc/ntp.keys" # e.g. contains: 123 M YOUR_MD5_KEY
trustedkey 123
broadcast 224.0.1.1
broadcastclient
multicastclient 224.0.1.1 key 123 preempt
manycastserver 224.0.1.1
manycastclient 224.0.1.1 key 123 preempt prefer



# ntp.conf for A / B (Clients and/or Servers) Add:
peer 192.168.1.10 iburst prefer preempt key 123
peer 192.168.1.20 iburst prefer preempt key 123
pool pool.ntp.org preempt   # Won't hurt anything if the internet can't be reached



# ntp.conf for D,E,F,G (Clients and/or Servers) Add:
server 192.168.1.10 iburst prefer preempt key 123
server 192.168.1.20 iburst prefer preempt key 123


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