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Cisco NetFlow Collection Engine

Field Notice: FN - 62908 - New Zealand Daylight Saving Time Policy Changes Effective September 2007 - For NetFlow Collector (NFC)


September 5, 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

Netflow - all versions

  

Problem Description

The operating systems of most Cisco products that support Daylight Saving Time (DST) have built in mechanisms to automatically change the times, based on current user-selected rules. Once the new DST is implemented, the time on devices that maintain time zone information will continue to change according to the old method, unless changes are made.

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.

On April 30, 2007, Hon Rick Barker, Minister of Internal Affairs, announced a three week extension to the period of daylight saving. Daylight saving now runs from the last Sunday in September until the first Sunday in April.

Table 1 Summary of changes to Daylight Savings Time, represents New Zealand local time

Event

Prior to 2007

Year 2007 and After

Start

First Sunday in October

2:00 A.M. on September 30, 2007

(Last Sunday in September)

End

Third Sunday in March

3:00 A.M.on April 6, 2008

(First Sunday in April)

  

Problem Symptoms

As a result, the system clock, any applications or log timestamps that NFC writes to will be off by one hour after September 30, 2007.

Workaround/Solution

NFC requires up-to-date timezone data in the Java Runtime Environment (JRE) bundled with NFC so that files and reports that contain the time-of-day accurately reflect current Daylight Saving Time rules that are in effect. Timezone data in NFC's JRE should be updated using the TZupdater tool provided by Sun Microsystems when NFC is installed and whenever local Daylight Saving Time rules change.

Note: JRE timezone data that NFC depends on is separate from system timezone data. Although it is recommended that you should also update your operating system timezone data when local Daylight Saving Time rules change, NFC will report times correctly if only the JRE is updated.

Sun has provided general information about this topic in the article Timezone Data and the Java Runtime Environment. To see if a change announced recently for your location is reflected in the latest data provided by Sun, see Timezone Data Versions in the JRE Software.

To update the JRE timezone information for NFC:

Step 1 - Login as the system user that owns NFC files and processes; this account was specified when NFC was installed (nfcuser by default in 5.0.3). Run "umask" to verify that the current umask is not more restrictive than 022 (for example, not 077). If higher, set to 022 by running "umask 022".

Step 2 - Download the latest TZupdater tool from Sun. If you don't have a Sun Online Account, you will be prompted to create one. Information about the TZupdater tool including a link to the download location of the most recent version is available at

http://java.sun.com/javase/tzupdater_README.html

Step 3 - In a temporary directory, extract the zipped contents of the download file. This creates the subdirectory tzupdater-version containing the jar file tzupdater.jar.

Step 4 - Shut down NFC by running "/opt/CSCOnfc/bin/nfcollector shutdown". Verify that no java processes are running with "ps -ef | grep java".

Step 5 - Run the TZupdater tool to update JRE timezone information by running "/opt/CSCOnfc/jre/bin/java -jar path-to-tzupdater-files/tzupdater.jar -u".

Step 6 - Restart NFC.

Revision History

Revision

Date

Comment

1.0

05-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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