H3C S7500E Series Ethernet Switches Operation Manual

Operation Manual – NTP
H3C S7500E Series Ethernet Switches Chapter 1 NTP Configuration
1-5
z Originate Timestamp: the local time at which the request departed the client for the
service host.
z Receive Timestamp: the local time at which the request arrived at the service host.
z Transmit Timestamp: the local time at which the reply departed the service host for
the client.
z Authenticator: authentication information.
1.1.4 Operation Modes of NTP
Devices running NTP can implement clock synchronization in one of the following
modes:
I. Server/client mode
Network
ServerClient
Automatically works in
server/client 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
Clock synchronization
message (Mode 3)
Figure 1-3 Server/client mode
When working in the server/client 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 work in the server mode and send a
reply, with the Mode field in the messages set to 4 (server mode). Upon receiving the
replies from the servers, the client performs clock filtering and selection, and
synchronizes its local clock to that of the optimal reference source.
In this mode, a client can be synchronized to a server, but not vice versa.