12• Stratum: An 8-bit integer that indicates the stratum level of the local clock, with the value rangingfrom 1 to 16. Clock precision decreases from stratum 1 through stratum 16. A stratum 1 clock hasthe highest precision. A stratum 16 clock is not synchronized.• Poll: An 8-bit signed integer that indicates the maximum interval between successive messages,which is called the poll interval.• Precision: An 8-bit signed integer that indicates the precision of the local clock.• Root Delay: Roundtrip delay to the primary reference source.• Root Dispersion: The maximum error of the local clock relative to the primary reference source.• Reference Identifier: Identifier of the particular reference source.• Reference Timestamp: The local time at which the local clock was last set or corrected.• Originate Timestamp: The local time at which the request departed from the client for the servicehost.• Receive Timestamp: The local time at which the request arrived at the service host.• Transmit Timestamp: The local time at which the reply departed from the service host for the client.• Authenticator: authentication information.Operation modes of NTPDevices that run NTP can implement clock synchronization in one of the following modes:• Client/server mode• Symmetric peers mode• Broadcast mode• Multicast modeYou can select operation modes of NTP as needed. If the IP address of the NTP server or peer is unknownand many devices in the network need to be synchronized, you can adopt the broadcast or multicastmode. In the client/server and symmetric peers modes, a device is synchronized from the specified serveror peer, so clock reliability is enhanced.Client/server modeFigure 7 Client/server modeWhen working in client/server mode, a client sends a clock synchronization message to servers, with theMode field in the message set to 3 (client mode). Upon receiving the message, the servers automaticallywork in server mode and send a reply, with the Mode field in the messages set to 4 (server mode). Uponreceiving the replies from the servers, the client performs clock filtering and selection, and synchronizesits local clock to that of the optimal reference source.
