Field Notice: Cisco 12016 - Loss of Alarm Card Redundancy Does Not Generate an Alarm

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Updated:June 30, 2001

Document ID:FN13022

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June 30, 2001

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Products Affected

Product	Top Assembly		Printed Circuit Assembly		Comments	HW Rev.
Product	Part Number	Rev.	Part Number	Rev.	Comments	HW Rev.
GSR16-ALRM	800-05570-01	-A0	73-4266-03	-A0	ASY,ELMECH,MBPWR/ALRM BD,GSR16	N/A
GSR16-ALRM	800-05570-01	-A0	73-4266-03	-B0	ASY,ELMECH,MBPWR/ALRM BD,GSR16	N/A
GSR16-ALRM	800-05570-01	-B0	73-4266-03	-A0	ASY,ELMECH,MBPWR/ALRM BD,GSR16	N/A
GSR16-ALRM	800-05570-01	-B0	73-4266-03	-B0	ASY,ELMECH,MBPWR/ALRM BD,GSR16	N/A
GSR16-ALRM	800-05570-01	-A0	73-4266-03	-A0	ASY,ELMECH,MBPWR/ALRM BD,GSR16	N/A
GSR16-ALRM	800-05570-01	-A0	73-4266-03	-B0	ASY,ELMECH,MBPWR/ALRM BD,GSR16	N/A
GSR16-ALRM	800-05570-01	-B0	73-4266-03	-A0	ASY,ELMECH,MBPWR/ALRM BD,GSR16	N/A
GSR16-ALRM	800-05570-01	-B0	73-4266-03	-B0	ASY,ELMECH,MBPWR/ALRM BD,GSR16	N/A

Problem Description

The 12016 system requires at least one working alarm card. (The alarm card provides power to the system MBUS.) If the system is equipped with redundant alarm cards, and one of the alarm cards fails (as a result of the on-board 5V convertor malfunctioning or a blown -48V fuse), there is neither a hardware warning indication through light emitting diodes (LEDs) nor a software message indicating that alarm card redundancy has been lost. Therefore, a latent loss of alarm card redundancy exposes the system to total failure should the remaining alarm card subsequently fail.

Background

With the 48V fuse out or a malfunction of the alarm card on-board power supply, the Mbus module is still powered by 5V from the second alarm card. This is due to the power feed from 5V Mbus (from the second alarm board) sub-divided down through sensing circuits. Further divided, this lowered voltage is sensed by the Mbus module of the defective card and displayed as the 5V value for this alarm card. Mbus power redundancy is lost, but LEDs indicate "normal". This issue has been filed as Bug CSCdt70593.

This issue has been filed as Bug CSCdt70593 (registered customers only) .

Problem Symptoms

The redundant alarm card has a malfunction, but there is no warning indication either through LEDs or through a software error message.

Workaround/Solution

Engineering is currently working on bug CSCdt70593 (registered customers only) . This field notice will be updated when a resolution to that bug is available. Until the final resolution is available, the status of a redundant alarm card can be monitored by the show environment command.

The following is a partial output of a show environment command showing the output for the alarm boards (slots 24 and 25):

sys_gsr12016-2a#show environment 
Slot # Hot Sensor Inlet Sensor 
(deg C) (deg C)      
. 
24 NA NA 
25 NA NA 
. 
Slot # 3V 5V MBUS 5V 
(mv) (mv) (mv) 

24 NA 5320 5040      
25 NA 3584 5040 
. 
.

The normal value of 5V for an alarm card is >5000mV. In the above example, the alarm board in slot 25 indicates 3584mV and is defective. Although its faceplate LEDs are all normal and the value of Mbus 5V is still normal for this alarm card, it does not provide MBUS power redundancy and it should be replaced.

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
CSCdt70593 (registered customers only)	Mbus health LED isn't being turned on for boot failures

For More Information

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