Configuring Daylight Saving Time

Configuring Daylight Saving Time

To configure daylight saving time (summer time) in areas where it starts and ends on a particular day of the week each year, use the following global configuration mode command. To avoid automatically switching to summer time, use the no form of this command.

Rtr1(config)#clock summer-time zone recurring [week day month hh:mm week day month hh:mm [offset]]

The first week day month hh:mm is when daylight saving time starts, while the last one represents when it ends.

The following example specifies that summer time starts on the first Sunday in April at 2 A.M. and ends on the last Sunday in October at 2 A.M.:

Rtr1(config)# clock summer-time PDT recurring 1 Sunday April 2:00 last Sunday October 2:00

For those areas that have a varying daylight saving time, it’s possible to configure the exact date and time of the next summer time event by using either of the following global configuration mode commands. To avoid automatically switching to summer time, use the no form of this command.

Rtr1(config)#clock summer-time zone date month date year hh:mm month date year hh:mm [offset]

Rtr1(config)#no clock summer-time zone date month date year hh:mm month date year hh:mm [offset]

Rtr1(config)#clock summer-time zone date date month year hh:mm date month year hh:mm [offset]

Rtr1(config)#no clock summer-time zone date date month year hh:mm date month year hh:mm [offset]

In the following example, daylight saving time (summer time) for Pacific Daylight Time is configured to start on April 26, 1997 at 2 A.M. and end on October 12, 1997at 2 A.M. The show clock command with the Detail option displays the current settings:

Rtr1(config)#clock summer-time PDT date 26 Apr 2004 2:00 12 Oct 2004 2:00
Rtr1(config)#^Z
Rtr1#show clock detail
18:23:40.399 PST Thu Apr 15 2004
Time source is user configuration
Summer time starts 02:00:00 PST Mon Apr 26 2004
Summer time ends 02:00:00 PDT Tue Oct 12 2004
Rtr1#