250 | Debugging and Diagnosticsw w w . d e l l . c o m | s u p p o r t . d e l l . c o mOffline DiagnosticsThe offline diagnostics test suite is useful for isolating faults and debugging hardware.The diagnostics testsare grouped into three levels:• Level 0—Level 0 diagnostics check for the presence of various components and perform essential pathverifications. In addition, they verify the identification registers of the components on the board.• Level 1—A smaller set of diagnostic tests. Level 1 diagnostics perform status, self-test, access, andread/write tests for all the components on the board and test their registers for appropriate values. Inaddition, they perform extensive tests on memory devices (for example, SDRAM, flash, NVRAM,EEPROM) wherever possible.• Level 2—The full set of diagnostic tests. Level 2 diagnostics are used primarily for on-board MAClevel, Physical level, and external loopback tests and more extensive component diagnostics. Variouscomponents on the board are put into loopback mode, and test packets are transmitted through thosecomponents. These diagnostics also perform snake tests using virtual local area network (VLAN)configurations.Important Points to Remember• You can only perform offline diagnostics on an offline standalone unit. You cannot performdiagnostics if the ports are configured in a stacking group. Remove the port(s) from the stacking groupbefore executing the diagnostic test.• Diagnostics only test connectivity, not the entire data path.• Diagnostic results are stored on the flash of the unit on which you performed the diagnostics.• When offline diagnostics are complete, the unit or stack member reboots automatically.Running Offline DiagnosticsTo run offline diagnostics, follow these steps:1. Place the unit in the offline state using the offline stack-unit command from EXEC Privilege mode(Figure 22-3).Note: Diagnostic is not allowed in Stacking mode, including member stacking. Avoid stacking beforeexecuting the diagnostic tests in the chassis.The system reboots when the off-line diagnostics complete. This is an automatic process. A warningmessage appears when you implement the offline stack-unit command.Warning - Diagnostic execution will cause stack-unit to reboot after completion ofdiags.Proceed with Offline-Diags [confirm yes/no]:y
