31. Ntp Client Description; Introduction; The Ntp Timeserver Commands - Nokia ESB26 User Manual

31. NTP Client Description

Introduction

NTP (Network Time Protocol) is a protocol built on top of TCP/IP that assures accurate local
timekeeping with reference to radio, atomic or other clocks located on the Internet. This
protocol is capable of synchronizing distributed clocks within milliseconds over long periods.
It is defined in STD 12, RFC 1119 (definition from The Free On-line Dictionary of
Computing, http://wombat.doc.ic.ac.uk/).
BiNOS's NTP Client supports all features described in RFC-1059 (Version 1), RFC-1119
(Version 2) and RFC-1305 (Version 3), except for the DES and RSA authentication
mechanism. Support of these RFCs means that the NTP Client can synchronize its local clock
with NTP servers that support any of these documents. The maximal number of remote NTP
servers is restricted to 5. (BiNOS also supports the "Daytime" and "Time" remote
synchronization protocols defined in RFC867 and RFC868 respectively. These protocols
synchronize with only one server -- see the description of the time-server command in "The
NTP Timeserver Commands").
NTP has become a standard for Internet time synchronization. Most importantly, there are
more than 100000 free NTP timeservers in the world. Using the NTP protocol, the Nokia
ESB26 switch time can be synchronized by the network administrator almost anywhere in the
world with a minimal effort. Because of its mode of operation (a complicated election
algorithm and MD5 authentication) and the Nokia ESB26 switch capabilities, the NTP Client
is immune to almost any kind of network attack. Furthermore, the NTP Client guarantees high
precision time synchronization.
In brief, the NTP Client features are:
• Ability to synchronize with RFC-1059 (Version 1), RFC-1119 (Version 2) or
RFC-1305(Version 3) compatible NTP Servers;
•
MD5 authentication algorithm;
• Up to 5 remote NTP timeservers for polling.
NOTE
Because of some newly introduced features in the time synchronization of the Nokia ESB26
switch, commands for setting time synchronization differ slightly from commands in older
versions of BiNOS. Measures have been taken to preserve compatibility with older versions.
The new version supports old style commands in order to permit execution of previously
saved configurations.
However, it is strongly recommended NOT to use old style commands in the new version.

The NTP Timeserver Commands

Table 31-1 summarizes the NTP timeserver commands.
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