In a VSS setup, after insert of a module, it may be powered down after boot diagnostics and reports a TestLoopback error. Sample Messages: %DIAG-SW1_SP-3-MAJOR: Switch 1 Module 8: Online Diagnostics detected a Major Error. Please use 'show diagnostic result <target>' to see test results. %CONST_DIAG-SW1_SP-3-BOOTUP_TEST_FAIL: Switch 1 Module 8: TestLoopback failed on port(s) 1-48 %C6KPWR-SW1_SP-4-DISABLED: power to module in slot 8 set off (Diagnostic Failure) This issue could be seen in Active or Standby switch, or both. <B>Conditions:</B> This has been observed in 12.2(33)SXI1 and SXI2a
Insert all the new modules into the VSS switch(es) and do a complete VSS reload. Setting the bootup diagnostic level to 'bypass' is NOT a valid workaround.
This is a known bug and its seen quite frequently now, Bug id#CSCta37113.