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Cisco 2000 Series Wireless LAN Controllers

Field Notice: FN - 62646 - US Daylight Savings Time Policy Change Effective March 2007 - for Wireless Products


Revised March 10, 2007

January 31, 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

Products Affected

AIR350 - AIR-APC350-A-K9

AIR350 - AIR-APC350-E-K9

AIR350 - AIR-APC350-J-K9

AIR350 - AIR-APC350-S-K9

AIR350 - AIR-APR350-A-K9

AIR350 - AIR-APR350-E-K9

AIR350 - AIR-APR350-J-K9

AIR350 - AIR-APR350-S-K9

AIR350 - AIR-BR350-A-K9

AIR350 - AIR-BR350-E-K9

AIR350 - AIR-BR350-J-K9

AIR350 - AIR-BR350-S-K9

AIR350 - AIR-BR350-SS-A

AIR350 - AIR-BR350-SS-E

AIR350 - AIR-BR350-SS-J

AIR350 - AIR-BR350-SS-S

AIRINFR - AIR-WLC2006-K9

AIRINFR - WS-C3750G-24WS-S25

AIRINFR - WS-C3750G-24WS-S50

AIRINFR4100 - AIR-VPN-4100-K9

AIRINFR4100 - AIR-WLC4112-K9

AIRINFR4100 - AIR-WLC4124-K9

AIRINFR4100 - AIR-WLC4136-K9

AIRINFR4402 - AIR-WLC4402-12-K9

AIRINFR4402 - AIR-WLC4402-25-C4K

AIRINFR4402 - AIR-WLC4402-25-K9

AIRINFR4402 - AIR-WLC4402-50-C4K

AIRINFR4402 - AIR-WLC4402-50-K9

AIRINFU - WS-SVC-WISM-1-K9

PPN - AIR-WLC2106-K9

AIRMGMT - AIR-N-WCS-WB-10-K9

AIRMGMT - AIR-N-WCS-WL-10-K9

AIRMGMT - AIR-N-WCS-WL-EX-UG

AIRMGMT - AIR-N-WCS-WL-SU-K9

AIRMGMT - AIR-N-WCS-WL-UG-K9

AIRMGMT - AIR-N-WCS-WLB-100X

AIRMGMT - AIR-N-WCS-WLB-SITE

AIRMGMT - AIR-N-WCS-WLL-100X

AIRMGMT - AIR-N-WCS-WLL-SITE

AIRINFU - NM-AIR-WLC6-K9

AIR-LOC - 2.0.42.0

Problem Description

New U.S. Daylight Savings Times (DST) rules go into effect in March 2007. 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 3 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 1 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 DST in the U.S.

Beginning in March of 2007, DST will begin at 2 a.m. on the second Sunday in March and end at 2 a.m. on the first Sunday in November.

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

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 major 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

  • Wireless Lan Controller (WLC)

    Solution:

    None.

    Workaround:

    It is strongly recommended to set WLC for UTC (no offset).

    Then configure (off set) from the WLC GUI. This is done via: Commands -> Set Time -> Timezone: set both hours and minutes to 0.

    If the WLC is located in a region that does not use DST, such as Arizona, you may set the timezone offset on the WLC, and it will handle the timezone offset correctly.

    If the WLC is located in a region that uses DST, during standard time, run with the standard offset, then at the time when daylight rules take effect, manually tell the WLC to set the offset forward. When standard time resumes, manually tell the WLC to set the offset back.

    It is strongly recommended, in any case, to configure the WLC to get its time from an NTP server. Note that the NTP does not communicate any timezone offset and/or DST change information. It uses only UTC.

    NTP Implications:

    Although it might appear the use of NTP will avert any issues related to the DST time changes, NTP and DST are not directly related, and one does not help or hinder the other. The NTP is simply a means to synchronize clocks on different devices. Typically, NTP takes a reference clock from a source that is tied to the UTC and that time does not change regardless of DST. For instance, the Eastern Standard Time in the Unites States is five hours behind the UTC time when DST is not active and four hours behind when the US is observing Daylight Savings Time. DST configuration is very specific to the timezone in which the device is deployed, and is calculated on each individual device, according to device configuration, using the NTP time, if configured, as a reference.

  • Wireless Control System (WCS)

    Solution:

    Upgrade to version 4.0.87 or higher using Software Center page.

    Workaround:

    None.

  • Autonomous IOS (aIOS)

    Solution:

    Upgrade to 12.3(11)JA1 or 12.3(8)JEA1 using Software Center page. See Field Notice 62613 - IOS DST for details.

    Workaround:

    To configure DST on Cisco devices running Cisco IOS software, the clock summer-time command is used. Please refer to the Command Reference to perform changes and learn about how to assign Time Zone Name and UTC Offset.

  • AIRAP-350 and AIRBR-350

    VXWorks is in End of Engineering (EOE) status. The DST checkbox will not work correctly in the USA with the new 2007 DST and there are no plans to make it work.

    Solution:

    NA

    Workaround:

    NA

  • AIR-LOC, Locator Appliance

    Solution:

    Upgrade to 2.1.42.0 or higher using Software Center page.

    Workaround:

    None.

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

CSCsh22276 (registered customers only) & CSCsf99924 (registered customers only)

WLC

CSCsg12596 (registered customers only)

WCS

CSCsg70355 (registered customers only)

aIOS

CSCsg67865 (registered customers only)

Network Appliance

Revision History

Revision

Date

Comment

1.2

10-MAR-2007

Updated Workaround/Solution section. Changed wording in first step to "Then configure (off set) from the WLC GUI. This is done via: Commands -> Set Time -> Timezone: set both hours and minutes to 0."

1.1

09-MAR-2007

Added AIR-WLC2006-K9, NM-AIR-WLC6-K9, AIR-WLC2106-K9, WS-C3750G-24WS-S25, WS-C3750G-24WS-S50, WS-SVC-WISM-1-K9 to Products Affected section.

1.0

31-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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