debug cdp ip




debug cdp ip

no debug cdp ip


Syntax Description:

This command has no arguments or keywords.

Command Description:

To enable debug output for the IP routing information that is carried and processed by the Cisco Discovery Protocol (CDP), use the debug cdp ip privileged EXEC command. The no form of this command disables debugging output.

CDP is a media- and protocol-independent device-discovery protocol that runs on all Cisco routers.

You can use the debug cdp ip command to determine the IP network prefixes CDP is advertising and whether CDP is correctly receiving this information from neighboring routers.

Use the debug cdp ip command with the debug ip routing command to debug problems that occur when on-demand routing (ODR) routes are not installed in the routing table at a hub router. You can also use the debug cdp ip command with the debug cdp packets and debug cdp adjacency commands along with encapsulation-specific debug commands to debug problems that occur in the receipt of CDP IP information.


The following is sample output from the debug cdp ip command. This example shows the transmission of IP-specific information in a CDP update. In this case, three network prefixes are being sent, each with a different network mask.

Router# debug cdp ip

Writing prefix
Writing prefix
Writing prefix

In addition to these messages, you might see the following messages:

This message indicates that CDP is attempting to install the prefix into the IP routing table:

CDP-IP: Updating prefix in routing table

This message indicates a protocol error occurred during an attempt to decode an incoming CDP packet:

CDP-IP: IP TLV length (3) invalid

This message indicates the receipt of the IP prefix from a CDP neighbor connected via Ethernet interface 0/0. The neighbor IP address is 10.0.01.

CDP-IP: Reading prefix source via Ethernet0/0



Related Commands:

debug ip routing

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