Cisco 12000 Series Routers

False Field Diagnostic Test Failures on Older Cisco 12000 Line Cards

October 15, 2003

Products Affected

  • 4OC12/POS-IR-SC=

  • 4OC12/POS-MM-SC=

  • LC-1OC12/POS-SM=

  • LC-1OC12/POS-MM=

  • LC-4OC3/POS-SM=

  • LC-4OC3/POS-MM=

  • LC-1OC12/ATM-SM=

  • LC-1OC12/ATM-MM=

  • 4OC3/ATM-IR-SC=

Problem Description

Data path tests through Field Diagnostics on older generation Cisco 12000 line cards with fiber cables plugged in report false failures.


Field Diagnostics on Cisco 12000 line cards attempts to test as much of the unit under test (UUT) as possible. Some of these tests are Data Path tests, which generate traffic internally and loop it back at various points within the UUT, then compare the returned traffic with the original traffic. Any differences or error indications increase the chances of test failure.

When fiber cables are attached to ports of older line card being tested, foreign traffic may be introduced which will interfere with UUT, resulting in the test being flagged as a failure.

This problem is a result of hardware limitations on older Engine 0 and 1 based Cisco 12000 line cards designed before Field Diagnostics was released publicly

Note: A return materials authorization (RMA) will not fix this problem. Please use the software work around steps indicated below.

Problem Symptoms

Field diagnostics appears to fail when a fiber cable is connected to the line card. When the cable is removed the tests pass.

After launching Field Diagnostics on an older Cisco 12000 line card with fiber cables connected, the test output will indicate:

Field Diagnostics: **** slot x: first test failed: 23, TBM to PSA Packet - Framer Loopback, error 2


Note: Only a limited number of early Cisco 12000 line cards using Engine 0, 1, or 2 are affected by this problem.

Removing any external fiber cables from these line card ports prior to running Field Diagnostics will avoid false failures.

The most current Cisco 12000 Field Diagnostics releases include the following warning message for these earlier line cards:

Requested linecard has non-isolating PLIM: Limited internal loopback testing available: 
To run all internal loopback tests, use 'full' option. Cisco strongly recommends physical disconnection 
of port before running 'full' option. Loopback testing generates outbound traffic. Inbound traffic may 
cause false failures.   

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: