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Level 10
Level 10

Core issue

The system encounters a bus error when the processor tries to access a memory location that either does not exist (a software error) or does not respond properly (a hardware problem).

A bus error can be identified by looking at the output of the show version command provided by the router, if not power-cycled or manually reloaded.

When the show version EXEC command is issued, these errors may be displayed:

  • System returned to ROM by bus error at PC 0xXXXXXXXX, address 0xYYYYYYYY

  • 0xXXXXXXXX represents the program counter at which the router reloads.

  • 0xYYYYYYYY represents the address at which the router reloads.

This symptom is observed on a Multilayer Switch Feature Card 2(MSFC2) that runs Cisco IOS  Software Release 12.1(8b)E9 or later.


This issue is documented in Cisco bug ID CSCdx92013. There is no known workaround for this problem.

This is most likely a hardware problem of the MSFC2 daughtercard. No software upgrade is necessary.

For further assistance, please contact Cisco Technical Support online using the Cisco Technical Support.

For more information, refer to Troubleshooting Bus Error Crashes.

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