Field Notice: FN - 62545 - TCC and Fan Tray (FTA3-T) Have Communications Problem That Can be Caused by Internal Noise Causing TCC Resets

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Updated:March 6, 2008

Document ID:FN62545

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Revised March 6, 2008
March 8, 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.

Revision History

Revision	Date	Comment
1.2	06-MAR-2008	Removed Upgrade Form
1.1	25-MAY-2007	Added software version information to Problem Description and Workaround/Solution sections.
1.0	08-MAR-2007	Initial Public Release

Products Affected

Products Affected	Top Assembly		Hardware Revision
Products Affected	Part Number	Revision	Hardware Revision
15454-FTA3-T	800-23907-02, -03	All	New: 800-23907-04, A0
15454-FTA3-T=	800-23907-02, -03	All	New: 800-23907-04, A0

Problem Description

Communications between the TCC and some versions of the 15454-FTA3-T fan tray can be disrupted by internal system noise.

This fault is precipitated when external electrical noise is present in the system.
The results are an automatic TCC reset without an indication of the reason for the reset.
Operation will continue as normal. Some fan trays may be more susceptible to internal noise than others, due to normal manufacturing variances.

This issue will not occur when using TCC+, FTA3 version -01 or FTA-CC. This issue is reduced with FTA3 version -04 or with software versions 4.1.8.2, 5.0.8, 6.0.2, 7.0.4, 7.2.2, and 8.0.0.

The issue is entirely resolved in software versions 7.0.5, 6.0.3, 7.2.3, and 8.5.

Background

TCCs were resetting at a customer sites for no obvious reason. Traffic was not impacted.

Under lab test conditions it was discovered that electrical noise emissions from two small cables within the Fan Tray assembly was causing the TCC to reset.

Problem Symptoms

The TCC resets repeatedly for no apparent reason, but the system continues to operate normally.
Under extreme conditions the LCD display on the fan tray may look corrupted.
Traffic is not affected.

Workaround/Solution

A software change has been implemented to alleviate the TCC resets. CTC Software releases that have a partial fix are:
4.1.8.2, 5.0.8, 6.0.2, 7.0.4, 7.2.2, 8.0.0.
In these software releases, the incidence of reset will be reduced, although in some cases, the fan tray LCD may look corrupted.

Software releases with a complete fix are: 7.0.5, 6.0.3, 7.2.3 and 8.5.

The TCC will now automatically recheck the fan tray communication channel rather than resetting.
If the fan tray communications are actually down, an alarm will be raised.

Upgrading to any of the above software releases should correct this condition.
For customers unable to upgrade the software, there is a hardware improvement that makes the fan trays less susceptible to noise.

DDTS

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

DDTS	Description
CSCsd91472 (registered customers only)	15454 FTA: Fan Failure Caused TCC Resets
CSCse32518 (registered customers only)	TCC2 Restarts in case of Communication Loss with Fan Trays

How To Identify Hardware Levels

Check the Products Affected section at the top of this Field Notice.

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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