User's Manual

TimeLord Master Clocks
Operating and Installation Instructions
Issue 2.0 9-3
Supported Protocols
Time Protocol (RFC868)
RFC868 defines the original TIME protocol, which provides site-
independent, machine-readable date and time in response to
a request from a client PC.
When a request is received the TimeLord-Net responds with a 32-bit
time value corresponding to the number of seconds since
midnight of January 1
st
1900. This representation of time will
serve until the year 2036.
Time Protocol is supported in the UDP mode of operation.
(RFC868)
NTP (RFC1305 & RFC1119)
The Network Time Protocol (NTP) is the most widely used
computer time synchronisation protocol in use today. It
provides a mechanism to both organise a synchronisation
subnet and distribute precise time synchronisation information
to the local clocks of all participating computers. In most parts
of the Internet today it is possible to use NTP to provide
accuracy’s of tens of milliseconds, depending on the
characteristics of the synchronisation source, stratum of
operation, the local network paths and the client software
used.
The NTP standard has been designed so that it can provide
reliable operation with clients and servers of vastly different
specifications and across network paths with diverse delay and
jitter characteristics. Most users of Internet NTP
synchronisation make use of the standard NTP distribution
available from http://www.ntp.org. This software package
includes the full suite of NTP options and algorithms and has
been ported to a wide variety of hardware platforms ranging
from Personal Computers (PC’s) to supercomputers.
We would recommend that, in large hierarchical time
distribution projects, the standard NTP distribution be used on
the Stratum 2 and 3 servers for maximum redundancy and
client availability.
Network Time Protocol (NTP) v2, v3 and v4 clients are
supported in both unicast and broadcast modes of operation.
(RFC1305 & RFC1119)
SNTP (RFC2030 & RFC1769)
Simple Network Time Protocol (SNTP) v3 and v4 clients are
supported in both unicast and broadcast modes of operation.
(RFC2030 & RFC1769)
Simple Network Time Protocol (SNTP) is an adaptation of NTP,
which can be used for applications where the ultimate
performance and associated overhead of the full NTP
implementation is not required.
Most PC client software is based on the SNTP specification and
certainly for most intranet applications will provide a higher
degree of accuracy than is required.
Simple Network Time Protocol (SNTP) v3 and v4 clients are
supported in both unicast and broadcast modes of operation.
(RFC2030 & RFC1769)
Synchronisation Alarm Status
The NTP/SNTP version 4 message format has provision for a
two-bit ‘Leap Indicator’ code that gives indication of an
impending leap second and synchronisation alarm status.
When ‘nLoc’ is set (y), the TimeLord-Net Master Clock will return an
LI (Leap Indicator) value of ‘0’ if the clock is synchronised and
‘3’ if the clock is unsynchronised. When ‘nLoc’ is not set (n), the
TimeLord-Net Master Clock will return an LI (Leap Indicator) value of
‘0’ regardless of synchronisation status.
If the synchronisation source is set to ‘none’ and ‘nLoc’ is set,
the TimeLord-Net will return an LI (Leap Indicator) value of ‘3’.
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