User Manual

S350 Series 24-Port (PoE+) and 48-Port Gigabit Ethernet Smart Switches
Configure System Information User Manual47
Configure an SNTP Server
SNTP assures accurate network device clock time synchronization up to the millisecond.
Time synchronization is performed by a network SNTP server. The switch operates only as
an SNTP client and cannot provide time services to other systems.
Time sources are established by strata. Strata 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 strata:
• 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, through 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 that the original request was sent by the client.
•T2. Time that the original request was received by the server.
•T3. Time that the server sent a reply.
•T4. Time that 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 were 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
Server Stratum The claimed stratum of the server for the last received valid packet.
Reference Clock ID The reference clock identifier of the server for the last received valid packet.
Server mode The mode of the server for the last received valid packet.
Unicast Server Max
Entries
The maximum number of unicast server entries that can be configured on this client.
Unicast Server
Current Entries
The number of current valid unicast server entries configured for this client.
Broadcast Count The number of unsolicited broadcast SNTP messages that were received and processed
by the SNTP client since the last reboot.
Table 10. SNTP Global Status information (continued)
Field Description