Currently, I am doing a NTP time synchronization between two ubuntu pcs connected by a LAN cable. After I finish the setup, I find that the delay is around 0.170s (170ms), which is not acceptable since I expect a delay less than 30ms. What could be the reasons causing the delay? And how could I solve it?

  • how do you measure this delay? – pim Apr 24 '18 at 9:17

I assume you use ntpq, which gives delay in milliseconds. 0.170 in the delay column of ntpq -p means a delay of 0.170ms, not 0.170 seconds.

0.170ms is a reasonable delay over a switched ethernet. 170ms does not make a lot of sense.

Explanation of the output is given in the ntpq documentation:

Obtains a current list peers of the server, along with a summary of each peer's state. Summary information includes the address of the remote peer, the reference ID ( if this is unknown), the stratum of the remote peer, the type of the peer (local, unicast, multicast or broadcast), when the last packet was received, the polling interval, in seconds, the reachability register, in octal, and the current estimated delay, offset and dispersion of the peer, all in milliseconds. The character at the left margin of each line shows the synchronization status of the association and is a valuable diagnostic tool. The encoding and meaning of this character, called the tally code, is given later in this page.

My formatting.

  • 1
    Oh my god. I think you are correct. I thought the unit of delay in ntpq -p is in seconds. Thank you very much. – Teddy_NTU Apr 25 '18 at 5:57

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.