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Cisco IOS Software Releases 12.1 Mainline

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


Revised March 22, 2007

January 24, 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.


Products Affected

Product

Comments

10.x

all 10.x derived trains

11.x

all 11.x derived trains

12.x

all 12.x derived trains

Problem Description

New U.S. Daylight Savings Times rules go into effect in March 2007. Consequently, customers whose network components rely on the default U.S. summertime clock settings within Cisco IOS will be affected by the following problem.

For operating systems that have not been updated with the new U.S. DST policy changes, timestamps will exhibit a 1-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 1-hour time clock offset lasting one week beginning at 2 a.m. on the first Sunday in November.

Any time-dependent applications not running the upgraded Cisco IOS or workaround will be affected by this problem.

For Example:

Call Manager Functionality

- Phone time display(s) will be one hour off: IP Phone date and timestamp display is downloaded from Call Mgr Server. CallManager 4.x and below runs on MS Windows, CallManager 5.0x runs Linux. DST changes are done in OS.

- Call Detail Recording will be off by one hour: Meeting Place - voicemail, logging, display, and greetings will be one hour off.

- System logs will be off by one hour.

- If used, time based routing will be off by one hour.

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 a.m. on the second Sunday in March

to

2 a.m. on the first Sunday in November

For more information on the Energy Policy Act of 2005 please visit: http://frwebgate.access.gpo.gov/cgi-bin/getdoc.cgi?dbname=109_cong_bills&docid=f:h6enr.txt.pdf

(See Section 110)

Problem Symptoms

Impact to Networking Systems

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.

Network Time Protocol (NTP) Implications

Regardless of whether or not network components are configured to use differing clock sources - that is, UTC and NTP - networks will be affected when clock summer-time commands are enabled with incorrect parameters.

Workaround/Solution

Solution:

Migrate to the Cisco IOS releases which have integrated the new summertime rules.

Please refer to the enclosed Cisco IOS Migration Path Table which lists the Cisco IOS versions that currently provide a fix as well as projected publishing dates.

Customers may go to the Upgrade Planner (registered customers only) to download the recommended software versions that have integrated the fix.

Also, customers who would like to view the latest status regarding which Cisco IOS software versions have integrated a vulnerability fix for the U.S. DST changes can use Bug Navigator. Bug Navigator, also known as Bug Toolkit, is a tool available to Cisco customers and partners. You can access Bug Toolkit here (registered customers only) . Users will need a CCO username and password to access Bug Navigator. Reference Bug ID CSCsg70355 to retrieve information related the U.S. DST policy changes addressed in Cisco IOS. The "First Fixed-in Version" field highlights software versions that include the fix.

Workaround:

Manually change Cisco IOS summertime command.

To configure Daylight Saving Time (DST) on Cisco devices running Cisco IOS software, the set clock summertime command is used. Please refer to the Command Reference to perform changes and learn about how to assign Time Zone Name and UTC Offset.

Available patches for other operating systems:

Many of the major OS vendors have already released patches to avoid any problems that the change in daylight savings time can cause. Cisco recommends that you upgrade your OS versions with these patches.

This table provides some of the OS patch-related links:

Sun Microsystems

Microsoft Windows

IBM

The change in daylight savings time is sure to affect all Network Management applications that use system time resources. Therefore, Cisco highly recommends that you install these OS patches on all your application servers in order to minimize any impact of this event.

Each row of the Cisco IOS software table (below) describes a release train and the platforms or products for which it is intended. If a given release train needs the fix, then the earliest possible releases that contain the fix (the "First Fixed Release") and the anticipated date of availability for each are listed in the "Rebuild" and "Maintenance" columns. A device running a release in the given train that is earlier than the release in a specific column (less than the First Fixed Release) is known to be need the fix. The release should be upgraded at least to the indicated release or a later version (greater than or equal to the First Fixed Release label).

fn62613_jfbhda.jpg

DDTS

To follow the bug ID link below and see detailed bug information, you must be a registered user and you must be logged in.

DDTS

Description

CSCsg70355 (registered customers only)

Adopt new default summer-time rules from Energy Policy Act of 2005

Revision History

Revision

Date

Comment

1.4

22-MAR-2007

Updated the table in the Workaround/Solution - Changed all Cisco IOS version 12.0 and 12.1 references with the migration instructions "12.2(46) available 10-May-07" to "Migrate to 12.2(40a) or later".

1.3

09-MAR-2007

Updated the table in the Workaround/Solution section to include the latest information on available Cisco IOS software releases. Added paragraph above table with an explanation on how to understand the table.

1.2

07-MAR-2007

Updated the table in the Workaround/Solution section to include the latest information on available Cisco IOS software releases.

1.1

19-FEB-2007

Updated IOS list in Workaround/Solution section.

1.0

24-JAN-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:

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