NETGEAR GS108T-200NAS Software Administration Manual page 42

GS108T and GS110TP Smart Switch Software Administration Manual
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 since it is itself a stratum 2 device.
The following is an example of stratums:
• Stratum 0: A real-time clock is used as the time source, for example, a GPS system.
• 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: Time at which the original request was sent by the client.
• T2: Time at which the original request was received by the server.
• T3: Time at which the server sent a reply.
• T4: Time at which the client received the server's reply.
The device can poll Unicast server types for the server time.
Polling for Unicast information is used for polling a server for which the IP address is known.
SNTP servers that have been configured on the device are the only ones that are polled for
synchronization information. T1 through T4 are used to determine server time. This is the
preferred method for synchronizing device time because it is the most secure method. If this
method is selected, SNTP information is accepted only from SNTP servers defined on the device
using the SNTP Server Configuration page.
The device retrieves synchronization information, either by actively requesting information or at
every poll interval.
Time Configuration
Use the Time Configuration page to view and adjust date and time settings.
To display the Time Configuration page, click System  Management Time  SNTP Global
Configuration.
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v1.0, April 2010
Configuring System Information