Field Notice: Faulty Temperature Sensors in Cisco 12000 Series Internet Routers

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Updated:July 26, 2002
Document ID:FN13107

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Updated January 15, 2002
June 6, 2001

Products Affected

Product Comments
6DS3-SMB(=)   Within the serial number range: SDK04370000 - SDK0504ZZZZ
End Of Life (EOL) Product: Replace with 6DS3-SMB-B(=)
OC48E/POS-SR-SC-B(=)   Within the serial number range: SDK04370000 - SDK0504ZZZZ  
16OC3/POS-SM(=)   Within the serial number range: SDK04370000 - SDK0504ZZZZ  
OC48E/POS-1550-SC(=)   Within the serial number range: SDK04370000 - SDK0504ZZZZ  
OC48E/POS-LR-SC-B(=)   Within the serial number range: SDK04370000 - SDK0504ZZZZ  
4OC12E/POS-MM-SC(=)   Within the serial number range: SDK04370000 - SDK0504ZZZZ  
4OC12/POS-MM-SC-B(=)   Within the serial number range: SDK04370000 - SDK0504ZZZZ  
4OC12E/POS-IR-SC(=)   Within the serial number range: SDK04370000 - SDK0504ZZZZ  
4OC12/POS-IR-SC-B(=)   Within the serial number range: SDK04370000 - SDK0504ZZZZ  
OC48E/POS-SR-SC(=)   Within the serial number range: SDK04370000 - SDK0504ZZZZ  
OC48E/POS-SR-FC-B(=)   Within the serial number range: SDK04370000 - SDK0504ZZZZ  
OC48E/POS-1550-FC(=)   Within the serial number range: SDK04370000 - SDK0504ZZZZ  
OC48E/POS-LR-FC-B(=)   Within the serial number range: SDK04370000 - SDK0504ZZZZ  
GSR16/80-SFC(=)   Within the serial number range: SDK04370000 - SDK0504ZZZZ  
8OC3/POS-MM(=)   Within the serial number range: SDK04370000 - SDK0504ZZZZ  
GSR16/80-CSC(=)   Within the serial number range: SDK04370000 - SDK0504ZZZZ  
8OC3/POS-SM(=)   Within the serial number range: SDK04370000 - SDK0504ZZZZ  
OC192R0/POS-IR-B(=)   Within the serial number range: SDK04370000 - SDK0504ZZZZ  
OC48/SRP-SR-SC(=)   Within the serial number range: SDK04370000 - SDK0504ZZZZ  
OC48/SRP-LR-SC(=)   Within the serial number range: SDK04370000 - SDK0504ZZZZ  
6CT3-SMB(=)   Within the serial number range: SDK04370000 - SDK0504ZZZZ  
OC192R0/POS-SR-SC(=)   Within the serial number range: SDK04370000 - SDK0504ZZZZ  
3GE-GBIC-SC(=)   Within the serial number range: SDK04370000 - SDK0504ZZZZ  
GSR16/320-CSC(=)   Within the serial number range: SDK04370000 - SDK0504ZZZZ  
GSR16/320-SFC(=)   Within the serial number range: SDK04370000 - SDK0504ZZZZ  
6DS3-SMB-B(=)   Within the serial number range: SDK04370000 - SDK0504ZZZZ  
12DS3-SMB-B(=)   Within the serial number range: SDK04370000 - SDK0504ZZZZ  
OC48E/POS-SR-FC(=)   Within the serial number range: SDK04370000 - SDK0504ZZZZ  
6E3-SMB(=)   Within the serial number range: SDK04370000 - SDK0504ZZZZ  
12E3-SMB(=)   Within the serial number range: SDK04370000 - SDK0504ZZZZ  
OC48/POS-SR-SC(=) Within the serial number range: SDK04370000 - SDK0504ZZZZ
12DS3-SMB(=) Within the serial number range: SDK04370000 - SDK0504ZZZZ
EOL Product: Replace with 12DS3-SMB-B(=)

Serial Numbers

Sequential #
SDK04370000 - SDK0504ZZZZ

Problem Description

A defective temperature sensor in the Cisco 12000 Series Internet Router can indicate an incorrect temperature.

Background

The serial number range above corresponds to products manufactured between September 21, 2000, and January 31, 2001. Cisco product serial numbers falling outside this serial number range are not affected by this problem. Approximately 16 percent of products manufactured within the serial number range listed above were built with a defective temperature sensors. Of the 16 percent of products actually built with a defective temperature sensor, approximately:

  • 80 percent (or 13 percent of the products built during above period) will indicate a negative temperature.
  • 15 percent (or 2 percent of the products built during above period) will indicate an extremely high temperature.
  • 5 percent (or 1 percent of the products built during above period) will indicate an incorrect temperature in the middle range.

Problem Symptoms

The problem symptoms depend on what type of indication is given by the temperature sensor. This is described below.

Indicating a Negative Temperature

If the product was manufactured with a temperature sensor which indicates a negative temperature, the symptom will be a negative temperature indication from a show env command. In most cases, the indicated temperature does not change with changes in ambient temperature. Cisco IOS ® Software takes no adverse action for negative temperature indications. There is a risk that the product could actually overheat but still indicate a negative temperature, in which case Cisco IOS would not shut the product down when it should. However, the probability of this is very low (no greater than for any other product), and it does not pose a safety or fire risk.

Indicating an Extremely High Temperature

If the product was manufactured with a temperature sensor which indicates an extremely high temperature, the symptom will be that it is shut down by Cisco IOS within 3 minutes of initially being powered on. The table below provides more detailed information about Cisco IOS actions and consequences when a product is shut down due to over temperature.

  Action taken by SW Consequences of SW action
Linecards Shutdown linecard Linecard removed from service.
Active CSC/SFC Shutdown active CSC/SFC Standby CSC/SFC takes over and drives fabric clock.
Loss of CSC/SFC redundancy (no standby).
Standby CSC/SFC Shutdown standby CSC/SFC Loss of CSC/SFC redundancy (no standby)
SFC Shutdown SFC Standby CSC/SFC takes over.
Loss of CSC/SFC redundancy (no standby).

Indicating an Incorrect Temperature in the Middle Range

If the product was manufactured with a temperature sensor which incorrectly indicates a temperature in the middle range, the symptoms vary depending on where the temperature indication falls as described below:

Indicating Lower than Accurate

If the temperature sensor is indicating a temperature which is lower than what is accurate, the symptoms will be similar to the symptoms described above for indicating a negative temperature, but will be more difficult to detect. The indicated temperature will fluctuate with changes in ambient temperature. The indicated temperature may be a negative number or a positive number (but less than what is accurate). Cisco IOS takes no adverse action for temperature indications lower than what is accurate.

Indicating Higher than Accurate

If the temperature sensor is indicating a temperature which is higher than what is accurate, but below the critical point where Cisco IOS would shut down the product, the symptom will be an elevated temperature indication on a show env command. This may be difficult to detect. The indicated temperature will fluctuate with changes in ambient temperature. It is possible that a temperature sensor is indicating a temperature just below the critical point where Cisco IOS would shut down the product and a slight increase in ambient temperature would cause it to be shut down by Cisco IOS; however, such a condition (being just below the critical shutdown temperature) would cause warning messages to be sent to the console, so this condition would not be latent. Warning, critical and shutdown temperatures for Cisco IOS Software Release 12.0(17.1)S are given in the table below and are generally representative for other versions of Cisco IOS.

12016/12416
Location
Warning
Critical
Shutdown
Linecards
Inlet
60
63
68
Exhaust
70
73
78
SFC
Inlet
49
52
57
Exhaust
52
55
60
CSC
Inlet
52
55
60
Exhaust
62
65
70

12012
Location
Warning
Critical
Shutdown
Linecards
Inlet
48
50
55
Exhaust
51
53
58
SFC
Inlet
50
52
57
Exhaust
53
55
60
CSC
Inlet
53
55
60
Exhaust
63
65
70

12008
Location
Warning
Critical
Shutdown
Linecards
Inlet
48
50
55
Exhaust
51
53
58
SFC
Inlet
45
46
63
Exhaust
52
55
65
CSC
Inlet
50
55
62
Exhaust
55
59
70

Workaround/Solution

To identify a product with a defective temperature sensor from within the possibly-affected serial number range, follow the steps below:

  1. Any inlet temperature sensor reading below +10°C (+50°F) or above +45°C (+113°F) are defective.
  2. Any exhaust temperature sensors reading below +10°C (+50°F) are defective.
  3. Any exhaust temperature sensors reading more than 30°C (86°F) above the inlet temperature sensor reading are defective.

The steps above assume ambient temperature is between +15°C (+59°F) and +30°C (+86°F).

The steps above will correctly identify a defective temperature sensor a very high percentage of the time. Customer who have questions or concerns about specific products or temperature indications should contact the Cisco TAC for assistance (see below).

Customers who wish to exchange product with defective temperature sensors for good product should call the Cisco TAC and request a return material authorization (RMA) coded "warranty new" (WN), referencing this field notice. Units within the suspect Serial Number range which ship out of manufacturing have been screened for this failure and can be used.

How to View Serial Numbers

Product serial numbers can be viewed on-line by using the show diag command. A sample output from a show diag command with the serial number highlighted in red is given below: 

SLOT 3  (RP/LC 3 ): 4 Port Packet Over SONET OC-3c/STM-1 Multi Mode
  MAIN: type 33,  800-2396-02 rev N0 dev 3307
        HW config: 0x01    SW key: FF-FF-FF
  PCA:  73-2147-07 rev A0 ver 4
        HW version 1.1  S/N CAB0450GBPC
  MBUS: MBUS Agent (1)  73-2146-07 rev B0 dev 0
        HW version 1.2  S/N CAB0444FF36
        Test hist: 0xFF    RMA#: FF-FF-FF    RMA hist: 0xFF
  DIAG: Test count: 0xFFFFFFFF    Test results: 0xFFFFFFFF
  L3 Engine: 0 - OC12 (622 Mbps)
  MBUS Agent Software version 01.40 (RAM) (ROM version is 02.10)
  Using CAN Bus A
  ROM Monitor version 10.06
  Fabric Downloader version used 13.0A (ROM version is 13.0A)
  Primary clock is CSC 1
  Board is analyzed 
  Board State is Line Card Enabled (IOS  RUN )
  Insertion time: 00:00:11 (1w2d ago)
  DRAM size: 134217728 bytes
  FrFab SDRAM size: 67108864 bytes
  ToFab SDRAM size: 67108864 bytes
  0 crashes since restart

How to View Inlet and Exhaust Temperatures

Use the show env temp command. A sample output from a show env temp command is given below: 

Slot #  Hot Sensor      Inlet Sensor
         (deg C)          (deg C)

0          36.5            22.5
1          34.0            23.0
2          31.5            23.0
3          36.0            46.0  <--Bad inlet sensor
4          33.5            22.0
6         -55.5            22.5  <-- Bad exhaust sensor
7          33.0            26.0
17         33.5            23.0
18         22.5            26.0
19         23.0            24.0
20         22.5            23.5
26         NA              23.0

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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