The debug commands enable detailed debug information for various protocols.
Debug output is generally seen by configuring a log with from debug-trace and then viewing the output of the log.
The currently enabled debug can be seen using the show debug command.
Debug configuration is not persistent across CPM switchovers nor router reboots. The admin debug-save command can be used to save the debug configuration. The resulting file could then be executed later as needed.
Individual debug commands are described in the 7450 ESS, 7750 SR, 7950 XRS, and VSR Classic CLI Command Reference Guide.