Table of Contents
Advertisement
NTP Support
NTP Support
The Network Time Protocol (NTP) is used to synchronize the time of a computer
client or server to another server or reference time source, such as a GPS receiver
or local timing source.
The SSU-2000 implements the NTP v.3 (RFC 1305) version. It can run as a server
application and a client application. In addition, a broadcast mode may be
implemented as either a server or client. The NTP server always runs and the client
and broadcast modes are enabled independently by assignment of addresses and
setting of timers.
Server Mode
The NTP server application always runs at port 123 (default NTP port) of the unit IP
address and responds to requests for time in the NTP format. If the unit has time set
from GPS then it indicates it is a primary time source by a 0 in the LI field and a 1 in
the STR field. It the unit has time set by the client application then it indicates it is a
secondary source by putting a 0 in the LI field and the source server STR + 1 in the
STR field.
If the unit time has not been set by one of the above then it indicates that time is not
valid by setting the LI field to 3. Once the unit time has been set by either radio or
client then LI = 0. Setting time by the keyboard sets (or leaves) LI = 3, since this is
not an accurate time setting. If the time has been set, and the unit switches to a
non-radio reference, then the STR becomes the PQL value for the selected
reference input. If the unit enters holdover mode then the STR becomes the PQL of
the selected Clock. (PQL is an internal representation of the received or assigned
SSM value of the reference. See the SSU-2000 documentation for details.)
Client Mode
If a valid time server IP other than 0.0.0.0 (default) is assigned AND a client timer
other than 0 (default) is set AND no radio time is available, then the unit will request
time from port 123 of the assigned server IP at the designated time interval (32 to
1024 seconds). Once time is set by the client mode then the server will have LI = 0
and STR = the time source STR + 1. A second server IP may be entered and the
NTP protocol will check both servers and select the best source per the NTP
specifications. An NTP response received in the client mode overrides the time set
by keyboard and changes the LI field to 0 as indicated above.
382 SSU-2000 User's Guide
12713020-002-2 Revision D – April 2004
Advertisement
Table of Contents
Troubleshooting
