Regarding CDP

[Ahmed Malik]

Hi,

    The CDP command is used to get the info about all the neighboring devices that are directly connected to the device on which it is performed so in order to map a network with the help of cdp command, right? Or its like we first perform it on one router get info of all the directly connected devices and then move onto next device in line in order to get info about router/switch connected to that device?

Regards,

Ahmed

[nkarpysh · Accepted solution]

CDP is L2 protocol. Device running CDP on interface if that is

1. Globally enabled

2. Enabled on interface

What it is basicaly do - it is exchanging the cdp paclets on that interface with connected device. If the other device supports cdp - it replying back and they build kind of cdp neighborship and you now able to see other device connected to port via "show cdp neighbor" command. It does not map further the local interface. It only showes connected devices which support CDP. E.g. Cisco-3rd party - you will not see cdp neighbor, Cisco- Cisco (with cdp disabled ) - you will not see neighbor.

Only Cisco (cdp enabled) - Cisco (cdp enabled) will show neighbor.

To check furtehr the network you need to go from one device to another to see what are the connected nighbors of that particular device.

Hope this helps.

Nik