Managing the NTP service

How to identify the NTP servers from which the DataPower® Gateway obtains its current time.

About this task

The DataPower Gateway NTP (Network Time Protocol) service identifies which NTP servers to obtain the current time. After at least one NTP server is identified, the DataPower Gateway acts as a Simple Network Time Protocol (SNTP) client as described in RFC 2030. The time from the NTP server can differ from the time that the DataPower Gateway shows. The difference is because of the local DataPower Gateway time zone.

The DataPower configuration includes a refresh interval. With each refresh interval timer event, the NTP client processes a single transaction with the NTP server. When a leap second occurs, the NTP server or servers used by the DataPower Gateway might insert the leap second indicator into the NTP protocol header. This insertion is designed to stage the leap second event ahead of time. When the NTP server sets this signal in the NTP response, NTP clients can choose to add or remove 1 second. The NTP server administrator can decide to enable this property weeks or days before the event. The DataPower SNTP implementation ignores the leap second indicator and continues normal operation.

After a leap second event occurs, the DataPower SNTP implementation refreshes the current time reference from the NTP server and make corrections as needed. If the NTP server corrected its own time, the reference time that is passed to the DataPower Gateway includes all or a portion of the correction. If the correction on the NTP server is incomplete at the time of first request from the DataPower Gateway following the event, the full correction does not take place on the DataPower Gateway until the correction is fully completed on the NTP server.

The DataPower Gateway absorbs leap seconds as they are absorbed by the NTP server or servers and communicated as the reference time in responses sent to the DataPower Gateway. The DataPower Gateway logs the time change as an informational message. The following message reflects the 1 second change that is introduced by the leap second on an NTP server that used a step correction to implement a leap second.
7:59:07 PM system info 207 0x80e0031f ntp-service (NTP Service): NTP time adjustment of 1000097 microseconds

The DataPower implementation uses slew correction for offsets of 0.5 seconds or less and step corrections for offsets greater than 0.5 seconds. If the NTP server uses step correction to process leap second event, the DataPower Gateway uses a step correction.

By default, the DataPower Gateway issues requests to the first NTP server in the list and waits 750 milliseconds for a response. If this server is not available or does not respond within the allocated duration, the DataPower Gateway attempts to contact the next server in the list.

To view the latest status of the most recent NTP refresh, access NTP Refresh Status.

Procedure

  1. In the search field, enter ntp.
  2. From the search results, click NTP Service.
  3. Set the administrative state of the configuration.
  4. In the Comments field, enter a descriptive summary.
  5. In the NTP server field, enter the IP address or host name of an NTP server and click Add.
  6. Optional: Repeat the previous step to add another NTP server.
  7. In the Refresh interval field, enter the interval between the time-of-day requests that the DataPower Gateway generates when it is an SNTP client.
  8. In the Timeout field, enter the time to wait for a response from an NTP server before trying the next server in the list.
  9. Click Apply to save the changes to the running configuration.
  10. Click Save Configuration or Save changes to save the changes to the persisted configuration.

Results

After the page refreshes, review the data in the Local Time field.