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Using the Simple Network Time Protocol
Configuring and
Using SNTP
GMT
GMT
Offset in
Offset in
Hours
Minutes
+0:00
+0
-1:00
-60
-2:00
-120
-3:00
-180
-4:00
-240
The switch software supports the client portion of the Simple
Network Time Protocol (SNTP) Version 3 based on RFC1769. SNTP
can be used by the switch to update and synchronize its internal
clock from a Network Time Protocol (NTP) server. When enabled, the
switch sends out a periodic query to the indicated NTP server, or the
switch listens to broadcast NTP updates. In addition, the switch
supports the configured setting for Greenwich Mean time (GMT)
offset and the use of Daylight Savings Time. These features have
been tested for year 2000 compliance.
To use SNTP, follow these steps:
1. Identify the host(s) that are configured as NTP server(s).
Additionally, identify the preferred method for obtaining NTP
updates. The options are for the NTP server to send out
broadcasts, or for switches using NTP to query the NTP server(s)
directly. A combination of both methods is possible. You must
identify the method that should be used for the switch being
configured.
2. Configure the Greenwich Mean Time (GMT) offset and Daylight
Savings Time preference. NTP updates are distributed using GMT
time. To properly display the local time in logs and other
timestamp information, the switch should be configured with the
appropriate offset to GMT based on geographical location.
Table 2-7
describes GMT offsets.
Table 2-7 Greenwich Mean Time Offsets
Common Time Zone
References
GMT - Greenwich Mean
UT or UTC - Universal
(Coordinated)
WET - Western European
WAT - West Africa
AT - Azores
AST - Atlantic Standard
AT-9108, AT-8518, AT-8525, and AT-8550 User's Guide
Cities
London, England; Dublin, Ireland;
Edinburgh, Scotland ; Lisbon,
Portugal; Reykjavik, Iceland ;
Casablanca, Morocco
Azores, Cape Verde Islands
Brasilia, Brazil ; Buenos Aires,
Argentina; Georgetown, Guyana;
Caracas ; La Paz
2-21
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