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We have a network of 10 clients running Windows XP with meinberg ntp. Clients are syncing with two ntp servers over a 40Km wireless network using mikrotik devices. Some of clients are connecting to ntp servers over a hop to hop links. ntp servers are syncing with the Internet. The problem is ntp clients are become out of sync after two or three days. After I restart service everything is OK. I should do this procedure every two days. I want to know is this because of long way wireless link? My ntp conf files are simple:

server 192.168.1.2 iburst
server 192.168.1.3 iburst

Windows time service and firewall is disabled. Is there any solution? Am I missing any configuration option?

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check this out: serverfault.com/questions/379739/… –  user151413 Dec 31 '12 at 6:05
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2 Answers

up vote 4 down vote accepted

It is not "the wlan link" as "there is nothing in a wlan link that particularly blocks ntp".

It is possible that your link is unstable beyond what the NTP Clients can deal with, but that - would IMHO Show in other Areas, too. If you consider the WLAN link to be bad, then I would suggeset using the mikrotik traffic Generator functionality to get a better idea how much packet loss you have - time for a in depth Analysis.

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we have approximately 5% of packet loss. I want to know the solution because on the same link ftp is working fine. Today I have checked and computers on the same LAN of ntp servers are also loosing sync. Is this normal in ntp? What do you suggest? –  Majid Azimi Dec 31 '12 at 12:28
    
Fuck. Sorry, that drastig. 5% is terrible. I consider any line with more than 0.5% unusable, lines should have less than 0.1% loss. 2% is a Problem. With 5% you really HAVE a Problem. THis is not NTP - this is a terrible packet loss. YOu also have a ton of resents, slow Connections. I would not like to do voip or something other time critical over something like that. I also assume most Games would not work. 5% is a "broken line". Fix it. –  TomTom Dec 31 '12 at 14:05
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If I get it correct you are using the meinberg windows ntp program. What could help is:

server 192.168.1.2 iburst maxpoll 6
server 192.168.1.3 iburst maxpoll 6

The maxpoll adjustment will limit the interval between ntp requests to 64 seconds (2^6, hence the 6).

My guess is your wlan packet loss may vary during the day (RF is always magic) and this may confuse ntpd.

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