Ntp Message Format - H3C S3100V2-52TP Configuration Manual

NTP message format

NTP uses two types of messages: clock synchronization messages and NTP control messages. An NTP
control message is used in environments where network management is needed. Because it is not
essential for clock synchronization, it is not described in this document.
NOTE:
All NTP messages mentioned in this document refer to NTP clock synchronization messages.
A clock synchronization message is encapsulated in a UDP message, in the format shown in
Figure 6 Clock synchronization message format
0 1
LI VN
The clock synchronization message format includes the following fields:
• LI (Leap Indicator): A 2-bit leap indicator. When set to 1 1, it warns of an alarm condition (clock
unsynchronized). When set to any other value, it is not to be processed by NTP.
VN (Version Number): A 3-bit version number that indicates the version of NTP. The latest version
•
is version 3.
• Mode: A 3-bit code that indicates the work mode of NTP. This field can be set to these values:
0—reserved
1—symmetric active
2—symmetric passive
3—client
4—server
5—broadcast or multicast
6—NTP control message
7—reserved for private use.
4 7
Mode Stratum
Root dispersion (32 bits)
Reference identifier (32 bits)
Reference timestamp (64 bits)
Originate timestamp (64 bits)
Receive timestamp (64 bits)
Transmit timestamp (64 bits)
Authenticator (optional 96 bits)
15
Poll
Root delay (32 bits)
11
23 31
Precision
Figure 6.