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Cisco Aironet 350 Series

Field Notice: FN - 62894 - New Zealand Daylight Saving Time Policy Change Effective September 2007 - Wireless Products


September 13, 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-01-NEWZEALAND

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-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 - NM-AIR--WLC6-K9

AIRINFU - WS-SVC-WISM-1-K9

PPN - AIR-WLC2106-K9

 

Problem Description

New New Zealand Daylight Saving Time rules go into effect in September 2007.

For operating systems that have not been updated with the new DST policy changes, timestamps will exhibit a one hour time clock offset lasting three weeks beginning in September of 2007.

Background

On April 30, 2007, the Minister of Internal Affairs issued a statement regarding a change in Daylight Saving Time policy for New Zealand. The change in policy has modified the start and end dates for Daylight Saving Time (DST). Beginning in 2007 and beyond, Daylight Saving Time in New Zealand will start on the last Sunday of September at 2:00 A.M. local time and end on the first Sunday of April at 3:00 A.M. local time.

Specifically for 2007-2008, Daylight Saving Time will begin at 2:00 A.M. local time on September 30, 2007, and end at 3:00 A.M. local time on April 6, 2008.

For more information, see the statement issued by the Minister of Internal Affairs: Daylight saving to be extended.

The old Daylight Saving Time policy dictated that DST started on the first Sunday in October and ended on the third Sunday in March.

Problem Symptoms

In these timeframes:

-September 30, 2007 to October 6, 2007

-March 15, 2008 to April 6, 2008

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.

Workaround/Solution

Wireless Lan Controller (WLC)

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 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 Network Time Protocol does not communicate any timezone offset and/or DST change information; it uses only UTC.

Network Time Protocol (NTP) Implications

Although it might appear the use of NTP will avert any issues related to the DST time changes, NTP and Daylight Savings Time are not directly related, and one does not help or hinder the other.

The Network Time Protocol is simply a means to synchronize clocks on different devices.

Typically, NTP takes a reference clock from a source that is tied to the Coordinated Universal Time (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 Daylight Savings Time 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.

Solution:

None

For Wireless Control System (WCS):

Solution:

Upgrade to version 4.0.97.0 or higher.

Wireless Software Downloads (registered customers only)

Workaround:

None

For Autonomous IOS (aIOS):

Solution:

Upgrade to 12.4(3g)JA1 or 12.3(8)JEB1

Wireless Software Downloads (registered customers only)

Workaround:

Please refer to the IOS Command Reference Guide to perform changes and learn about how to assign Time Zone Name and UTC Offset.

AIRAP-350 and AIRBR-350

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

Solution:

NA

Workaround:

NA

AIR-LOC (Location Appliance)

Workaround:

NA

Solution:

Upgrade to 2.1.42.0 or higher.

Wireless Software Downloads (registered customers only)

Revision History

Revision

Date

Comment

1.0

13-SEP-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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