Netgear GS752TP GS728TP/GS728TPP/GS752TP Software Administration Manual - Page 32

GS752TP, GS728TP, and GS728TPP Gigabit Smart Switches Time The switch software supports the Simple Network Time Protocol (SNTP). You can also set the system time manually SNTP assures accurate network device clock time synchronization up to the millisecond. Time synchronization is performed by a network SNTP server. The software operates only as an SNTP client and cannot provide time services to other systems. Time sources are established by stratums. Stratums define the accuracy of the reference clock. The higher the stratum (where 0 is the highest), the more accurate the clock. The switch is a stratum 2 device, and as such accepts stratum 1 or higher time indications. 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, 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 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 screen. The device retrieves synchronization information, either by actively requesting information or at every poll interval. Time Configuration Use the Time Configuration screen to view and adjust date and time settings.  To configure the time by using the CPU clock cycle as the source: 1. Select System  Management  Time  SNTP Global Configuration. Configuring System Information 32