Configuration Guide Configuring NTP
DEVICE-B (B for short) is used as an NTP reference clock source, DEVICE-A (A for short) is used as an NTP client that
synchronizes time with DEVICE-B. At a time point, the local clock of A is 19:00:00 and the local clock of B is 19:30:20.
1. A sends an NTP request packet. The local time (T0) when the packet leaves from A is 19:00:00 and is filled in Originate
Timestamp.
2. After a 2-second network delay, the local time (T1) when B receives the request packet is 19:30:23 and is filled in
Receive Timestamp.
3. B processes the NTP request and sends an NTP response packet one second later. The local time (T2) when the
response packet leaves from B is 19:30:24 and is filled in Transmit Timestamp.
4. After a 2-second network delay, A receives the response packet. The local time (T3) when the response packet arrives
at A is 19:00:06.
The specific calculations for time synchronization are as follows:
A obtains the time difference of 30 minutes and 20 seconds between B and A by using the formula ((T1-T0)+(T2-T3))/2.
A obtains the packet round-trip delay of four seconds between A and B by using the formula (T3-T0)-(T2-T1).
NTP Working Mode
External clock reference mode
In this mode, a device is used as both a server and a client. If receiving time synchronization requests from other clients, the
device must synchronize time with the specified server first and provide time synchronization for the clients after successful
synchronization.
Local clock reference mode
In this mode, a device uses the default local clock as the reliable clock source and provides time synchronization directly for
other clients.
Related Configuration
Configuring an NTP Server
The NTP function is disabled by default.
Run the ntp server command to specify an NTP server (external clock reference source), which can enable NTP.
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