Allied Telesis AT-8000GS User's Guide download pdf (Page 20)

Configuring System Time

Page 20

The Clock Source and System Time sections of the System Time Page contain the following fields:

• Clock Source — The source used to set the system clock. The possible field values are:

– Local Settings — Indicates that the clock is set locally.

– SNTP — Indicates that the system time is set via an SNTP server.

• System Time — Sets the local clock time. The field format is HH:MM:SS. For example: 21:15:03.

• System Date — Sets the system date. The field format is Day/Month/Year. For example: 04/May/50 (May 4,

2050).

• Time Zone Offset — The difference between Greenwich Mean Time (GMT) and local time. For example, the

Time Zone Offset for Paris is GMT +1, while the Time Zone Offset for New York is GMT –5.

To set the system clock:

2. Select the system time mode.

3. Define the System Date, System Time and Time Zone Offset fields.

4. Click Apply in each section. The local system clock settings are saved, and the device is updated.

5. Click Save Config on the menu to save the changes permanently.

Configuring SNTP

The device supports the Simple Network Time Protocol (SNTP). SNTP assures accurate network device clock

time synchronization up to the millisecond. Time synchronization is performed by a network SNTP server. The

device operates only as an SNTP client, and cannot provide time services to other systems. The device can poll

the following server types for the server time:

• Unicast

• Anycast

• Broadcast

Time sources are established by stratums. Stratums define the accuracy of the reference clock. The higher the

stratum (where zero is the highest), the more accurate the clock. The device receives time from stratum 1 and

above. The following is an example of stratums:

Stratum 0 — A real time clock (such as a GPS system) is used as the time source.

Stratum 1 — A server that is directly linked to a Stratum 0 time source is used. Stratum 1 time servers provide

primary network time standards.

Stratum 2 — The time source is distanced from the Stratum 1 server over a network path. For example, a Stratum

2 server receives the time over a network link, via NTP, from a Stratum 1 server.

Polling for Unicast Time Information

Polling for Unicast information is used for polling a server for which the IP address is known. T1 - T4 are used to

determine the server time. This is the preferred method for synchronizing device time.

Polling for Anycast Time Information

Polling for Anycast information is used when the SNTP server IP address is unknown. The first Anycast server to

return a response is used to set the time value. Time levels T3 and T4 are used to determine the server time.

Using Anycast time information for synchronizing device time is preferred to using Broadcast time information.

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Allied Telesis AT-8000GS User's Guide Page 20