Ntp Message Format - HP 5820X Switch Configuration Manual

NTP message format

NTP uses two types of messages, clock synchronization message and NTP control message. An NTP
control message is used in environments where network management is needed. Because it is not a must
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 20 Clock synchronization message format
The following main fields are described below:
• LI (Leap Indicator)—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)—3-bit version number that indicates the version of NTP. The latest version is
•
version 3.
Mode—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.
• Stratum—8-bit integer that indicates 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—8-bit signed integer that indicates the poll interval, namely the maximum interval between
successive messages.
Precision—8-bit signed integer that indicates the precision of the local clock.
•
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Figure 20.