Configuring Sntp; Polling For Unicast Time Information; Polling For Anycast Time Information - Alcatel OS-LS-6224 User Manual

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Configuring the Switch

Configuring SNTP

Simple Network Time Protocol (SNTP) allows the switch to set its internal clock
based on periodic updates from a time server (SNTP or NTP). Maintaining an
accurate time on the switch enables the system log to record meaningful dates and
times for event entries. You can also manually set the clock using the CLI. If the
clock is not set, the switch will only record the time from the factory default set at the
last bootup.
Note: The system time is not saved in NVRAM.
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 is. 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.

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 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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