Symmetricom Time Server Leap Indicator Version Number Mode Stratum Poll Precision, Bit Meaning

Appendix A: NTP Version 3, NTPQ, and NTPDC NTP V 3.0 Data Format per RFC-1305

Leap Indicator Version Number

Mode

Stratum

Poll

Precision

Synchronizing Distance (Root Delay Version 3)

Synchronizing Dispersion (Root Dispersion Version 3)

Reference Clock Identifier

Reference Timestamp

Originate Timestamp

Receive Timestamp

Transmit Timestamp

Authenticator

Figure A-1 NTP Data Packet Information Layout

Leap Indicator

The leap indicator is a 2 bit code that signals an impending leap second to be added or subtracted in the last minute of the current day. Leap year codes and their corresponding meanings are shown in Table A-1below:

Table A-1 Leap Year Codes

Bit 0

Bit 1

Meaning

0	0	Normal Operation
0	1	61 second last minute
1	0	59 second last minute
1	1	Clock not synchronized

The unsynchronized state is indicated by TimeVault whenever the estimated synchronization error is greater than the root dispersion. Such conditions typically occur following turn-on, until synchronization with the external source has been achieved, and whenever the external synchronization input has been removed and the extrapolated time error has exceeded the value of the root dispersion.

Version Number

The version number is a three bit integer that specifies the NTP version. TimeVault will copy this field from the client requesting packet and return it in this field if it is equal to either 2 or 3. NTP version 1 packets are not supported.

Mode

The mode is a three bit integer that determines the functions TimeVault performs. TimeVault operates in mode four or server mode. Mode four operation allows the module to synchronize hosts but will not allow the module to be synchronized by another host.

A-92 TimeVault™ User’s Manual 6000-100AppA.fm Rev. C