Field Notice: FN74353 - Cisco Network Convergence Systems 560 Series Routers May Not Display Accurate Fan Speed Readings upon Occurrence of Fault in the Fans Impacting Router Operation - Software Upgrade Recommended

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Updated:February 20, 2026
Document ID:FN74353

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High
Impact Rating:
High
First Published:
2026-Feb-20
Last Published:
2026-Feb-20
Revision:
1.0
Cisco Bug IDs:

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


Affected Product Name Description Comments
N560-4 N560 4RU Chassis HW with RSP4  
N560-4-CC N560 4RU CC Chassis HW with RSP4  
N560-4-E NCS 560 4RU Chassis HW with RSP4-E, PSU options and FAN  
N560-4-E-CC NCS 560 4RU CC Chassis HW with RSP4-E, PSU options and FAN  
N560-4-SYS N560 4RU HW. Flex. Consumption for RSP4. Smart Licensing  
N560-4-SYS-E N560 4RU HW. Flex. Consumption for RSP4-E. Smart Licensing  
N560-7 N560 7RU Chassis HW with RSP4  
N560-7-E NCS 560 7RU Chassis HW with RSP4-E, PSU options and FAN  
N560-7-SYS N560 7RU HW. Flex. Consumption for RSP4. Smart Licensing  
N560-7-SYS-E N560 7RU HW. Flex. Consumption for RSP4-E. Smart Licensing  
N560-7-SYS-E-V N560 7RU HW. for RSP4-E. ATO for Volume based discounting  
N560-7-SYS-V N560 7RU HW. for RSP4. ATO for Volume based discounting  
N560-FAN-H NCS 560 High Speed Fan  




Defect Information


Defect IDHeadline
CSCwr48966NCS560: Speed of all fans in FT stuck (static) in the "show environment fan" output

Problem Description


Cisco Network Convergence Systems (NCS) 560 Series routers may not display accurate fan speed readings when one or more fans develops a fault during normal operation. When one fan develops a fault, the remaining fans in the router do not rotate at maximum speed, which can lead to chassis shutdown due to overheating.


Background


When one or more fans develop a fault during normal operation, Cisco IOS XR Software stops processing additional fan sensor data that updates current fan speeds and other parameters. This issue is fixed in Cisco IOS XR Release 25.2.2 and later.


Problem Symptom


To validate the fan speed discrepancy, run the CLI command show environment fan in multiple iterations in close intervals. If the output readings always report the same rotating speed and the fan speed readings appear to be static, then the fan trays have the failure signature that is described in this field notice.


Workaround/Solution


To fix the issue that is described in this field notice, Cisco recommends installing the SMU for Cisco IOS XR Software Release 7.10.2, as shown in the following table.

Note: The fix is incorporated in Cisco IOS XR Release 25.2.2 and later.

Cisco IOS XR Software Release SMU Type SMU Download Instructions
7.10.2 Reload
  1. Go to the Cisco Software Download page.
  2. Choose Routers > Service Provider Edge Routers > Network Convergence System 560 Series Routers > [the appropriate Cisco NCS 560 Series Router].
  3. Choose IOS XR Software Maintenance upgrades (SMU).
  4. From the left navigation pane, choose the software release 7.10.2.
  5. Install SMU with the description ISSU/Reload/Recommended SMU, NCS560: Speed of all fans in FT stuck (static) in the 'show environment fan' output.

Revision History


VersionDescriptionSectionDate
1.0Initial Release—2026-FEB-20

For More Information

For further assistance or for more information about this field notice, contact the Cisco Technical Assistance Center (TAC) using one of the following methods:

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