1-2z Defining the accuracy of clocks by stratum to synchronize the clocks of all devices in a networkquicklyz Supporting access control (see section Configuring Access Control Right) and MD5 encryptedauthentication (see section Configuring NTP Authentication)z Sending protocol packets in unicast, multicast, or broadcast modez The clock stratum determines the accuracy, which ranges from 1 to 16. The stratum of a referenceclock ranges from 1 to 15. The clock accuracy decreases as the stratum number increases. Astratum 16 clock is in the unsynchronized state and cannot serve as a reference clock.z The local clock of an S4500 Ethernet switch cannot be set as a reference clock. It can serve as areference clock source to synchronize the clock of other devices only after it is synchronized.Implementation Principle of NTPFigure 1-1 shows the implementation principle of NTP.Ethernet switch A (Device A) is connected to Ethernet switch B (Device B) through Ethernet ports. Bothhaving their own system clocks, they need to synchronize the clocks of each other through NTP. To helpyou to understand the implementation principle, we suppose that:z Before the system clocks of Device A and Device B are synchronized, the clock of Device A is setto 10:00:00 am, and the clock of Device B is set to 11:00:00 am.z Device B serves as the NTP server, that is, the clock of Device A will be synchronized to that ofDevice B.z It takes one second to transfer an NTP message from Device A to Device B or from Device B toDevice A.
