HP Cisco MDS 9020 Cisco MDS 9000 Family Command Reference - Cisco MDS SAN-OS R - Page 115

Chapter 1 CLI Overview Using Debug Commands Send documentation comments to [email protected] To enable all system diagnostics, enter the debug all command at the command line in privileged EXEC mode. For example: switch# debug all To turn off all diagnostic output, enter the no debug all command at the command line in privileged EXEC mode. For example: switch# no debug all Using the no debug all command is a convenient way to ensure that you have not accidentally left any debug commands turned on. Caution Because debugging output takes priority over other network traffic, and because the debug all command generates more output than any other debug command, it can severely diminish the performance of the router or even render it unusable. In virtually all cases, it is best to use more specific debug commands. Generating debug Command Output Enabling a debug command can result in output similar to the following example for the debug modem command: Router# debug modem 15:25:51: TTY4: DSR came up 15:25:51: tty4: Modem: IDLE->READY 15:25:51: TTY4: Autoselect started 15:27:51: TTY4: Autoselect failed 15:27:51: TTY4: Line reset 15:27:51: TTY4: Modem: READY->HANGUP 15:27:52: TTY4: dropping DTR, hanging up 15:27:52: tty4: Modem: HANGUP->IDLE 15:27:57: TTY4: restoring DTR 15:27:58: TTY4: DSR came up The router continues to generate such output until you enter the corresponding no debug command (in this case, the no debug modem command). If you enable a debug command and no output is displayed, consider the following possibilities: • The router may not be properly configured to generate the type of traffic you want to monitor. Use the more system:running-config EXEC command to check its configuration. • Even if the router is properly configured, it may not generate the type of traffic you want to monitor during the particular period that debugging is turned on. Depending on the protocol you are debugging, you can use commands such as the TCP/IP ping EXEC command to generate network traffic. Redirecting debug and Error Message Output By default, the network server sends the output from debug commands and system error messages to the console. If you use this default, monitor debug output using a virtual terminal connection, rather than the console port. To redirect debug output, use the logging command options within configuration mode as described in the following sections. OL-16217-01, Cisco MDS SAN-OS Release 3.x Cisco MDS 9000 Family Command Reference 1-41