Overview of global debugging Methods for Cisco routers

There are a lot of users using Cisco routers, global debugging of Cisco routers here today I would like to introduce you, I hope to be useful to you.

The boundaries of global and interface commands are obvious when conducting Cisco router configuration. In this case, we use the global to identify the commands that cannot be used for interface debugging or for specific transport media types and protocol debugging.

In the 2500 series Cisco routers, you can use the Debug command to analyze the Cisco Discovery Protocol (Cisco Discovery PROTOCOL,CDP). We telnet to the Cisco router remotely. By default, the output of the debug command is sent to the console, and if you are in a Telnet session, we can use the Terminal Monitor command to view the output.

First, the Protocol debugging

Debug commands are applicable to all other protocols and are related to IP protocols.

(1) Display ARP debugging

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ARP debugging starts, and then clears the ARP cache, resulting in ARP requests and responses. First, we use the command to erase all ARP caches on the Cisco router, so every LAN segment connected by Cisco routers will generate ARP messages. Because we do not need to generate too many ARP packets, the selected Cisco router is connected to only one Ethernet segment.

(2) Display IP RIP debugging

At the start of debugging, the Cisco router table is not emptied because the router automatically makes a RIP update every 30 seconds, so there is no need to force an update. Similar to the first example, all debugging should be turned off after sufficient information has been obtained.

Second, interface debugging

The Debug Serial interface command is a debugging command that relates directly to the Cisco router interface and the type of transport media. In the following example, the serial interface uses the HDLC package. End-to-end HDLC Keep active messages exchanged every 10 seconds. This indicates that the link operation is normal and the second tier is working properly. Show Interface Serial0 command indicates that the line protocol is starting normally. Use the Undebug all command to turn off all debugging.

Cisco routers in each series have different debugging methods and can generally use debug commands to analyze Cisco discovery protocols.