beautypg.com

Ntp operation modes, Client/server mode – H3C Technologies H3C SecPath F1000-E User Manual

Page 112

background image

101

Stratum—An 8-bit integer indicating the stratum level of the local clock, with the value ranging from

1 to 16. The clock precision decreases from stratum 1 through stratum 16. A stratum 1 clock has the
highest precision, and a stratum 16 clock is not synchronized and cannot be used as a reference

clock.

Poll—An 8-bit signed integer indicating the poll interval, namely the maximum interval between
successive messages.

Precision—An 8-bit signed integer indicating the precision of the local clock.

Root Delay—Roundtrip delay to the primary reference source.

Root Dispersion—Maximum error of the local clock relative to the primary reference source.

Reference Identifier—Identifier of the particular reference source.

Reference Timestamp—Local time at which the local clock was last set or corrected.

Originate Timestamp—Local time at which the request departed the client for the service host.

Receive Timestamp—Local time at which the request arrived at the service host.

Transmit Timestamp—Local time at which the reply departed the service host for the client.

Authenticator—Authentication information.

NTP operation modes

Devices that run NTP can implement clock synchronization in one of the following modes:

Client/server mode

Symmetric peers mode

Broadcast mode

Multicast mode

You can select operation modes of NTP as needed. If the IP address of the NTP server or peer is unknown

and many devices in the network need to be synchronized, you can adopt the broadcast or multicast

mode; while in the client/server and symmetric peers modes, a device is synchronized from the specified
server or peer, and thus clock reliability is enhanced.

Client/server mode

Figure 45 Client/server mode

When operating in client/server mode, a client sends a clock synchronization message to servers, with

the Mode field in the message set to 3 (client mode). Upon receiving the message, the servers

automatically operate in server mode and send a reply, with the Mode field in the messages set to 4

Network

Server

Client

Clock

synchronization

message

(Mode3)

Automatically works in

client/server mode and

sends a reply

Reply

( Mode 4)

Performs clock filtering and

selection, and synchronizes its

local clock to that of the

optimal reference source