TP-Link TL-SL3428 manual Configuring SNTP, SNTP Overview, Polling for Unicast Time Information

4. Click . The DST settings are saved, and the device is updated.

3.2 Configuring SNTP

This section contains the following topics:

SNTP Overview

Defining SNTP Global Settings

Configuring SNTP Authentication

Defining SNTP Servers

Defining SNTP Interface Settings

3.2.1 SNTP Overview

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.

Information received from SNTP servers is evaluated based on the Time level and server type. SNTP time definitions are assessed and determined by the following time levels:

T1 — The time at which the original request was sent by the client.

T2 — The time at which the original request was received by the server.

T3 — The time at which the server sent the client a reply.

T4 — The time at which the client received the server's reply.

3.2.1.1 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.

3.2.1.2 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.

3.2.1.3 Polling for Broadcast Time Information

Broadcast information is used when the server IP address is unknown. When a broadcast message is sent from an SNTP

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