Field Notice: FN - 62717 - U.S. Daylight Saving Time (DST) Policy Changes Effective March 2007 - Cisco Unified Survivable Remote Site Telephony (SRST)

February 19, 2007

NOTICE:

THIS FIELD NOTICE IS PROVIDED ON AN "AS IS" BASIS AND DOES NOT IMPLY ANY KIND OF GUARANTEE OR WARRANTY, INCLUDING THE WARRANTY OF MERCHANTABILITY. YOUR USE OF THE INFORMATION ON THE FIELD NOTICE OR MATERIALS LINKED FROM THE FIELD NOTICE IS AT YOUR OWN RISK. CISCO RESERVES THE RIGHT TO CHANGE OR UPDATE THIS FIELD NOTICE AT ANY TIME.

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Products Affected

Products Affected
1760V - CISCO1760-V-SRST
2651XM - CISCO2651XM-V-SRST
2800 - C2851SEC/K9-U-SRST
2801 - C2801-VSEC-SRST/K9
2801 - CISCO2801-SRST/K9
2811 - C2811-VSEC-SRST/K9
2811 - C2811SEC/K9-U-SRST
2821 - C2821-VSEC-SRST/K9
2821 - C2821SEC/K9-U-SRST
2851 - C2851-VSEC-SRST/K9
2851 - CISCO2851-SRST/K9
3825 - C3825-VSEC-SRST/K9
3845 - CISCO3845-SRST/K9
3825 - CISCO3825-SRST/K9

Problem Description

New U.S. Daylight Saving Time rules go into effect in March 2007.

For SRST systems that have not been updated with the new U.S. DST policy changes, timestamps will exhibit a one hour time clock offset lasting three weeks beginning at 2 A.M. on the second Sunday in March of 2007. They will also exhibit a one hour time clock offset lasting one week beginning at 2 A.M. on the first Sunday in November.

Background

On August 8, 2005, the Energy Policy Act of 2005 (H.R.6.ENR), was signed into law. Section 110 of this Act modified the time change dates for Daylight Saving Time (DST) in the U.S.

Beginning in March of 2007, DST will begin on the second Sunday of March and end the first Sunday of November.

For 2007 and beyond, the daylight saving time period will be:

2:00 A.M. on the second Sunday in March

to

2:00 A.M. on the first Sunday in November

For more information on the Energy Policy Act of 2005 please see H.R. 6. (See Section 110)

Problem Symptoms

During a failover scenario, IP Phones connected to the SRST system and Call Detail Records (CDR) get their time based on the time setting in IOS on the SRST Router. To show the correct time when DST changes in March and Nov 2007, the correct dates need to be specified on a yearly basis if your area changes time for DST.

Networking systems often make use of local time to mark logs, as well as to schedule certain events, such as IP SLA schedule starts, or the beginning or end of a time-based access-list.

In addition, inconsistencies between time zone definitions may impact event correlation systems as well as other management systems relating to problem escalation. Having accurately represented local time is a very big concern for most organizations. Local time may be reflected in logs and on phone displays. This is especially true of systems that require accurate time and time stamping for proper operations.

For networking systems, the clock or clock source is often derived from a trusted chronological source such as a private or public Atomic clock, often through Network Time Protocol (NTP). NTP communicates time in Coordinated Universal Time (UTC), colloquially known as GMT, and thus is not impacted, nor is a workaround for statutory time zone changes. Local time definitions, including summertime settings are part of the configuration of most Cisco products.

Workaround/Solution

Cisco SRST is an IOS based application. Thus, the Daylight Saving Time Configuration parameters for a system running IOS can be easily changed with a single configuration command. This command can be run at any time and on any device to alter the current default settings of the given device.

clock summer-time zone recurring [week day month hh:mm week day month hh:mm [offset]]

For example, to configure the new settings for DST in calendar year 2007, one can enter the following command:

clock summer-time EDT recurring 2 Sun Mar 2:00 1 Sun Nov 2:00

For more information on IOS, see:

Field Notice: FN - 62613 - U.S. Daylight Savings Time Policy Changes Effective March 2007 - for Cisco IOS Software

For more information on phone firmware updates, see:

Field Notice: FN - 62666 - US Daylight Savings Time Policy Change Effective March 2007 - for Cisco Unified IP Phones 7900 Series

Revision History

Revision	Date	Comment
1.0	19-FEB-2007	Initial Public Release

For More Information

If you require further assistance, or if you have any further questions regarding this field notice, please contact the Cisco Systems Technical Assistance Center (TAC) by one of the following methods:

• Open a service request on Cisco.com
• By email
• By telephone

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