H3C Technologies H3C SR8800 - Manual (Page 66)

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A clock synchronization message is encapsulated in a UDP message, in the format shown in Figure 20 .
Figure 20 Clock synchronization message format
Main fields are described as follows:
• LI—A 2-bit leap indicator. When set to 11, it warns of an alarm condition (clock unsynchronized);
when set to any other value, it is not to be processed by NTP.
• VN—A 3-bit version number, indicating the version of NTP. The latest version is version 3.
• Mode—A 3-bit code indicating 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—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—The maximum error of the local clock relative to the primary reference source.
• Reference Identifier—Identifier of the particular reference source.
• Reference Timestamp—The local time at which the local clock was last set or corrected.
• Originate Timestamp—The local time at which the request departed the client for the service host.
• Receive Timestamp—The local time at which the request arrived at the service host.
• Transmit Timestamp—The local time at which the reply departed the service host for the client.
• Authenticator—Authentication information.
LI VN Mode Stratum Poll Precision
0 7 15 23 31
Root delay (32 bits)
Root dispersion (32 bits)
Reference identifier (32 bits)
Receive timestamp (64 bits)
Transmit timestamp (64 bits)
Authenticator (optional 96 bits)
Reference timestamp (64 bits)
Originate timestamp (64 bits)
1 4