Check the NTP Peers

Purpose

Ensure that the clock time on the router is synchronized with the time on the NTP server.

Action

To check NTP peers, enter the following Junos OS CLI operational mode command:

Sample Output 1

     remote           refid      st t when poll reach   delay   offset  jitter
==============================================================================
*coetanian.junip .GPS.            1 u   22   64  377    6.861   -1.297   0.811

Sample Output 2

>      remote           refid      st t when poll reach   delay   offset  jitter
> ==============================================================================
>  ntp1.usno.navy. PSC.            1 -   44   64   77   86.829  -1830.3 915.177
>  Tick.UH.EDU     USNO.           1 -   36   64   77   42.560  -1835.3 917.667

Meaning

Sample output 1 is synchronized with the NTP server because there is an asterisk (*) at the beginning of the output. Also, the router with the asterisk (*) is the master router and the system is synchronizing with this NTP server.

Sample output 2 shows that the time on the server and router is so far apart that NTP will not attempt to synchronize. The offset value of 1830 is too large a difference and the jitter value of 917.667 is also too large to provide reliability to the offset value.

In ordinary conditions, the NTP server synchronizes the router clock in small steps so that the timescale is effectively continuous. In conditions of extreme network congestion, the NTP server discards sample offsets exceeding 128 ms, unless sample offsets are greater than 128 ms, for longer than 900 seconds. In this case, no matter what the next offset, the NTP server adjusts to the indicated time.

For more detailed information on configuring the NTP server, see the Junos System Basics Configuration Guide.