Operation Manual – NTPH3C S5500-EI Series Ethernet Switches Chapter 1 NTP Configuration1-2z In analysis of the log information and debugging information collected fromdifferent devices in network management, time must be used as reference basis.z All devices must use the same reference clock in a charging system.z To implement certain functions, such as scheduled restart of all devices within thenetwork, all devices must be consistent in timekeeping.z When multiple systems process a complex event in cooperation, these systemsmust use that same reference clock to ensure the correct execution sequence.z For increment backup between a backup server and clients, timekeeping must besynchronized between the backup server and all the clients.Advantages of NTP:z NTP uses a stratum to describe the clock precision, and is able to synchronizetime among all devices within the network.z NTP supports access control and MD5 authentication.z NTP can unicast, multicast or broadcast protocol messages.1.1.2 How NTP WorksFigure 1-1 shows the basic work flow of NTP. Switch A and Switch B are interconnectedover a network. They have their own independent system clocks, which need to beautomatically synchronized through NTP. For an easy understanding, we assume that:z Prior to system clock synchronization between Switch A and Switch B, the clock ofSwitch A is set to 10:00:00 am while that of Switch B is set to 11:00:00 am.z Switch B is used as the NTP time server, namely Switch A synchronizes its clockto that of Switch B.z It takes 1 second for an NTP message to travel from one switch to the other.
