Using meinberg ntp over 40Km wireless network

Question

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?

check this out: http://serverfault.com/questions/379739/how-well-will-ntpd-work-when-the-latency-is-highly-variable — , Dec 31 '12 at 06:05

score 4 · Accepted Answer · answered Dec 31 '12 at 06:18

4

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.

answered Dec 31 '12 at 06:18

TomTom

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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

score 0 · Answer 2 · answered Jan 30 '13 at 12:44

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.

Using meinberg ntp over 40Km wireless network

2 Answers2