Time Protocols
3
i!-TimeManager
Time Protocols
i!-TimeManager supports four time protocols:
DayTime (13/udp, 13/tcp)
Time (37/udp, 37/tcp)
SNTP (123/udp)
SNTP Broadcast (123/udp)
Only one of the protocols can be active at a time.
DayTime Protocol
The DayTime protocol is based on RFC 867 and can provide Day and Time information. While the
Daytime protocol can provide accurate day and time formation, RFC867 does not specify the actual
format for the message. This limits the usefulness of the DayTime protocol with one exception: The
National Institute of Standards and Technology operate a series of Time Servers, known as the
NIST Internet Time Servers, that provide a DayTime message of fixed format than can be reliably
parsed and can be used to accurately set the Day and Time of any clock. While these Time Servers
reside in the US, the Day and Time of the servers is supplied in Universal time Coordinates or
UTC. i!-TimeManager is capable of connecting to any of the NIST Time servers and calculating the
correct time and date for any location in the world. i!-Time Manager also supports the standard
NIST server list, a file called nist-srv.lst, and will attempt to read this file from doc:\user\time. You
may get a copy of this file from the /pub directory on any NIST timeserver. If this file cannot be
found on the NetLinx file system, a default list of NIST servers will be used instead. See the NIST
home page at
http://www.boulder.nist.gov/timefreq/index.html
for more information on NIST Time
service or Servers.
Additionally, i!-TimeManager has also been written to use a "popular" DayTime format which is
used by the Linux implementation of DayTime and Tardis, a popular time syncing software.
Although not specified, the Date and Time of this format does not specify the time zone and is
assumed to be local. If you select DayTime protocol and select a server that is running DayTime
and the format, specifically "DayOfWeek Month Day HH:MM:SS Year", can be found, no time
offset will be added. If you have chosen this combination and find that the time does not
synchronize to the correct time, choose another protocol or server.
