tailieunhanh - CCNA 1 and 2 Companion Guide, Revised (Cisco Networking Academy Program) part 68

Cisco Networking Academy Program CCNA 1 and 2 Companion Guide, Revised part 68 is the Cisco approved textbook to use alongside version of the Cisco Networking Academy Program CCNA 1 and CCNA 2 web-based courses. The topics covered provide you with the necessary knowledge to begin your preparation for the CCNA certification exam (640-801, or 640-821 and 640-811) and to enter the field of network administration. | Page 639 Tuesday May 20 2003 2 53 PM Getting Information About Remote Devices 639 Example 13-6 show interfaces Command Output Continued 22146 packets output 2383680 bytes 0 underruns 0 output errors 0 collisions 2 interface resets 0 restarts 1 carrier transitions The statistics reflect router operation since the last time the counters were cleared. Use the clear counters command to reset the counters to 0. By starting from 0 you get a better picture of the current status of the network. The show interfaces command can also be used to check the status of other interface types such as Ethernet E0 Fast Ethernet Fa0 and Integrated Services Digital Network ISDN BRI0 . Checking Real-Time Traffic with the debug Command The router includes hardware and software to aid it in tracking down problems on it or on other hosts in the network. The debug privileged EXEC command starts the console display of the network events specified in the command parameter. Use the terminal monitor command to forward debug output to your Telnet session terminal. Figure 13-10 displays the data-link broadcasts received by the router using the debug broadcasts command. Use the undebug all or no debug all command to turn off debugging when you no longer need it. Debugging is really intended for solving problems. CAUTION Figure 13-10 Checking Real-Time Traffic with the debug Command Be careful with the debug command on a live network. Substantial debugging on a busy network slows the network significantly. Do not leave debugging turned on use it to diagnose a problem and then turn it off. Excessive debugging on routers with minimal RAM can cause the router to force a reload. By default the router sends system error messages and output from the debug EXEC command to the console terminal. However you can redirect messages to a UNIX host or to an internal buffer. The terminal monitor command enables you to redirect these messages to a terminal which can be useful in cases where you use a UNIX