Cisco 10700 Series Routers

Field Notice: Cisco 10720 Fan Failure Goes Undetected

Revised March 27, 2002

February 27, 2002

Products Affected


Top Assembly

Printed Circuit Assembl

Part Number


Part Number












Problem Description

Fan failures go undetected, but temperature alarms still function normally.


A design error on the main board results in fan failures going undetected. If an overtemperature condition occurs as a result of a fan failure, an overtemperature alarm will be generated properly. Overtemperature alarm thresholds are given below for reference:

Router#show environment table 
Sample Point      LowCritical    LowWarning     HighWarning    HighCritical 
chassis inlet                                   40C/104F       50C/122F 
chassis outlet0                                 43C/109F       53C/127F 
chassis outlet1                                 43C/109F       53C/127F 
System shutdown for chassis inlet 65C/149F 
System shutdown for chassis outlet0 75C/167F 
System shutdown for chassis outlet1 75C/167F

Problem Symptoms

In the event of an actual fan failure, no alarms will be generated unless an overtemperature condition exists. Checking fan status using the show environment all command will falsely indicate the fans are working, displaying Fan 1 status is believed to be ok.


Replace the defective hardware.

As of approximately Mar 11, 2002 new products that are manufactured under the engineering change order (ECO) for this issue are guaranteed to be free of this problem. Refer to How to Identify Hardware Levels below for instructions on how to view the version of in-service product. Product shipped from Service Logistics however, may still exhibit this problem. The ECO initiates a global purge of Service Logistics inventory. A global purge of Service Logistics inventory takes between 6 and 12 months to complete. This field notice will be updated when the purge is complete. Until the purge is complete, to get product at the new version, submit a return materials authorization (RMA) coded ARFN (Adminisrative Request - Field Notice).

How To Identify Hardware Levels

Use the show diags 0 command to view the 800-level part number of the Cisco 10720 main board. In the example shown below, the main board has an 800-level part number of 800-15309-02 (shown in bold) and is therefore affected by the problem described in this field notice.

Router#show diags 0
  Main FPGA ver: 0x0003
  PCA (73) Item Num: 73-05349-03
  PCA (73) Item Num - Rev: A0
  Fab (28) Ver: 3
  Unit (800) Item Num: 800-15309-02
  Unit (800) Item Num - Rev: A0
  Serial Number: CAT0532003G
  Van Allen Memory Size: 64 MB
  Toaster Memory Size - Column 1: 32 MB
  Toaster Memory Size - Column 2: 128 MB
  Toaster Memory Size - Column 3: 32 MB
  Toaster Memory Size - Column 4: 32 MB
  Toaster Memory Size - Column 5: 32 MB
  Toaster Memory Size - Column 6: 32 MB
  Toaster Memory Size - Column 7: 32 MB
  Toaster Memory Size - Column 8: 32 MB

  Power supply: AC powered
  PCA (73) Item Num: 73-05425-02
  PCA (73) Item Num - Rev: A0
  Fab (28) Ver: 2
  Unit (800) Item Num: 800-09550-01
  Unit (800) Item Num - Rev: A0
  Serial Number: CAT0532003X
  Chassis MAC Address: 0006.D74B.0980
  MAC Address block size: 128

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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