HP 6125G HP 6125G & 6125G/XG Blade Switches Network Management and Mon - Page 18

LI Leap Indicator, VN Version Number, Stratum, Precision

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used in environments where network management is needed. Because NTP control messages are not essential for clock synchronization, they are not described in this document. A clock synchronization message is encapsulated in a UDP message in the format shown in Figure 6. Figure 6 Clock synchronization message format The main fields are described as follows: • LI (Leap Indicator)-A 2-bit leap indicator. If set to 11, it warns of an alarm condition (clock unsynchronized). If 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 4. • Mode-A 3-bit code that indicates the operation 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 that indicates the stratum level of the local clock, with the value ranging from 1 to 16. 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. • Poll-An 8-bit signed integer that indicates the maximum interval between successive messages, which is called the poll interval. • Precision-An 8-bit signed integer that indicates the precision of the local clock. 11

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11
used in environments where network management is needed. Because NTP control messages are not
essential for clock synchronization, they are not described in this document.
A clock synchronization message is encapsulated in a UDP message in the format shown in
Figure 6
.
Figure 6
Clock synchronization message format
The main fields are described as follows:
•
LI (Leap Indicator)
—A 2-bit leap indicator. If set to 11, it warns of an alarm condition (clock
unsynchronized). If 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 4.
•
Mode
—A 3-bit code that indicates the operation 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 that indicates the stratum level of the local clock, with the value ranging
from 1 to 16. 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.
•
Poll
—An 8-bit signed integer that indicates the maximum interval between successive messages,
which is called the poll interval.
•
Precision
—An 8-bit signed integer that indicates the precision of the local clock.