On 2013-07-31, Biswajit Panigrahi <[email protected]> wrote: > Hi , > Basically my intention is to get notification in client when ever the > connection between server changes(Ex-lan connectivity OR ntp server itself is > down).For that I am doing the following step:
ntp is NOT the way to test connectivity. That is not its purpose. > > In client: > 1.Execute ntpq -c associations > 2.Get the data in status field > 3.If there is any change in that field ,then collect the 4th bit of > that.(Ex:f69a & 1000) > 4.If its 1 then reachable else unreachable. > > But the problem I am facing is: > Whenever the connectivity between the server goes down, the status field > will not change immediately. > My observation was whenever the reach field of ntpq -p command comes to zero > then only the status field changes. > That's why I was trying to reduce the time gap. And you are running into a lack of knowledge of how ntp works. ntp sends our query packets, which is 2^p sec where p is the poll number-- between 6 and 10 by default. Ie, ntpd has not idea that the remote server is down untill it has polled it. ntpd collects the last 8 querries and uses only the one with the shortest roundtrip time. Thus it does not care if there is no response for a few polls. ntpd knows that there could be a huge number of possible reasons for a poll to get lost and does not worry about it. Why do you? > > If My approach is not correct then please suggest me the other approach. approach to what? What is the problem you are trying to solve? > > -----Original Message----- > From: [email protected] > [mailto:[email protected]] On > Behalf Of David Taylor > Sent: Wednesday, July 31, 2013 12:46 AM > To: [email protected] > Subject: Re: ntpq -p command query > > On 30/07/2013 15:24, Biswajit Panigrahi wrote: >> Hi, >> >> I have configured the ntp server and ntp client on two machine. >> >> Both are communicating properly. I would like to test when the >> connectivity between those two goes down, after how much time the >> "reach" option in ntpq -p command becomes zero. >> >> For that I stopped the ntp server and I executed the ntpq -p in >> client's console, >> >> The reach option will still keep on increase to 377 then gradually >> decreases to zero. The time duration to come to zero is almost 20 >> minute. >> >> Can we reduce the time gap ? > [] >> Regards, >> >> Biswajit > > Biswajit, > > Look for a value not equal to 377, rather than 0. Possibly 376 would be > the first indication of a problem. > > 20 minutes (actually 1024 seconds) is the polling interval which will be > reached in a stable default configuration, so as others have said, > reduce the value of maxpoll for servers which are local to your network > (i.e. not public servers). On my own network, I typically have maxpoll > set to 5 for local servers, and minpoll set to 10 for Internet servers. _______________________________________________ questions mailing list [email protected] http://lists.ntp.org/listinfo/questions
