Setting the Router’s Time
The router’s internal clock is
set with the clock
set
command. This
command is not a configuration command (i.e., you must be in enable
mode to give it, but you don’t need to give the
configure
terminal
command) and
is not stored in the router’s configuration. The time is in
military (24-hour) time. For example:
Router#clock set 13:00:00 20 jun 1999
In addition to setting the time itself, you need to set the time zone
using the clock
timezone
command.
This command is part of the router’s configuration. For
example, a router on the east coast of the United States would have
the line:
Router(config)#clock timezone EST -5
-5 is the UTC (Coordinated Universal Time) offset for the Eastern time zone.
Now that the time and time zone have been set, one final configuration item exists: in most places, you want to observe Daylight Savings Time. The following command tells the router to use Daylight Savings Time in the Eastern time zone:
Router(config)#clock summer-time EDT recurring
The Calendar Versus the Clock
High-end
Cisco routers have a calendar that is separate from the system clock.
The calendar runs continuously, even if the router is off. After the
calendar has been set, the system clock automatically sets itself
every time the router is booted. The following commands set the
router’s calendar and set the clock’s time from the
calendar time. The
calendar
set
command simply
sets the time, and is not stored in the router’s configuration.
Router#calendar ...
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