What is the work of cisco discovery protocol cdp?

Cisco Discovery Protocol used to negotiate and announce special attributes from one device to the other, Cisco invented it, but there is some other vendors use it or at least can understand it.

It is used to share information about other directly connected Cisco equipments.

it's a propriotary cisco protocol that detects directly connected devices their type model and function

cdp run to enable it

show cdp neighbor

show cdp neighbor detail

It is used to share information about other directly connected Cisco equipment, such as the operating system version and IP address. CDP can also be used for On-Demand Routing, which is a method of including routing information in CDP announcements so that dynamic routing protocols do not need to be used in simple networks.

As a brief useful ansewer cdp is powerful monitoring and troubleshoooting cisco proprietary tool that operates at datalink layer.

CDP can be used to build logical network topology if such network documentation is missing or lacking in detail.

• by using the show cdp neighbors and show cdp neighbors detail commands we obtain the neighboring interfaces type and ip address.
• then we can use these informations to telneting the neighbor which gives we access to the device.
• by repeating this procedure from the neighboring device, we gather a full view about the network topology.

ghenimi,

best regards.

The Cisco Discovery Protocol (CDP) is a proprietary Data Link Layer protocol developed by Cisco Systems. It is used to share information about other directly connected Cisco equipment, such as the operating system version and IP address

CDP is layer2 protocol used to discover devices directly Connected to the router ( name , type, @ ip ...) and it is generally used when layer3 connexion is failed  ..the most used command is :

router # Show CDP neighbors details to see more details about devices like @IP..

it's a layer two protocol. it's used to share information about other directly connected Cisco devices for example if you execute the command "show cdp neighbor" in the privilege modem of a router it will show you the host name of the neighboring router,  your interface that is connecting you to the other device as well as device interface toward you.

CDP stands for Cisco Discovery Prodocol.

Simply it discovers Cisco devices which are directly connected to its interface.

It is a Cisco proprietary Protocol.So it won't detetct other brands apart from Cisco.

It is important to note the following points:

a. Should be directly connected

b. It only detects Cisco devices (Also detetcs HP as HP has an agreement).However you have to install CDP into other brand if you want to detetct it by CDP

You can use following commands:

#sh cdp neighbours

#sh cdp attribute

Example:

switch# show cdp neighbors

Capability Codes: R - Router, T - Trans-Bridge, B - Source-Route-BridgeS - Switch, H - Host, I - IGMP, r - Repeater,V - VoIP-Phone, D - Remotely-Managed-Device,s - Supports-STP-Dispute, M - Two-port Mac Relay  

Device ID Local Intrfce Hldtme Capability Platform Port ID

savbu-qa-dist-120 mgmt0177 S I WS-C3750E-24T Gig1/0/13

swor96(SSI13110AAQ) Eth1/17165 S I s N5K-C5010P-BF Eth1/19 

swor96(SSI13110AAQ) Eth1/18165 S I s N5K-C5010P-BF Eth1/20 

swor95(SSI13110AAS) Eth1/29171 S I s N5K-C5010P-BF Eth1/19

So, you can easily find out the name of Cisco device and see on which port it is connected.

CDP is enable by defult on all cisco devices. it is used for troubleshooting connectivity between Cisco Devices.To check the output of Cisco discovery protocol(CDP) use the following commands.

Syntax: show CDP.

To check the directly connected Cisco devices like hostname, interface to which it is connected, the model of the device ETC.

Syntax: show CDP Neighbour

This command will display Device id,Local interface, holdtime, capability,platform, and port id of the next switch to which  the interface is connected.

If you want to know the detail information about the directly connected Cisco devices or neighbour like IP address IOS version,platform of the remote device etc.

use this command,

Syntax: show CDP neighbour detail.

It's used to discover another cisco devices and get general info.