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DGS-3100 Series Gigabit Stackable Managed Switch User Manual
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 polls Unicast type servers for the
server time.
Time sources are established by stratums. Stratums define the accuracy of the reference clock. The higher 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
Stratum 0
Stratum 1
Stratum 2
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:
Time level
T1
T2
T3
T4
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Example
A real time clock (such as a GPS system) is used as the time source.
A server that is directly linked to a Stratum 0 time source is used as the time source. Stratum 1
time servers provide primary network time standards
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.
SNTP Time Definition
The time at which the original request was sent by the client.
The time at which the original request was received by the server.
The time at which the server sent the client a reply.
The time at which the client recived the server's reply.
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