Day-26: Cisco Discovery Protocol.

• CDP is a Cisco discovery protocol and it is a Cisco proprietary protocol.
• CDP is a Layer 2 protocol for neighbor discovery.
• CDP Provides information on the platform, interface, IP address, and OS version.
• CDP runs on the data-link layer and is enabled by default.
• CDP helps to prepare the map of the network diagram .

Enabling CDP.

Router(config)# cdp run
Router(config)# cdp timer

Disabling CDP.

Globally Disable.

Router(config)# no cdp run


Per Interface Disable.

Router(config)#interface fa0/0
Router(config-if)#no cdp enable

Verification commands,

Router# show cdp neighbor
Router# show cdp neighbor < interface>
Router# show cdp neighbor detail

CDP LAB.

CDP is by default enabled .now let’s verify in R2 & R3.

R3#show cdp neighbors 
Capability Codes: R - Router, T - Trans Bridge, B - Source Route Bridge
                  S - Switch, H - Host, I - IGMP, r - Repeater

Device ID        Local Intrfce     Holdtme    Capability  Platform  Port ID
R2               Fas 1/0            135        R S I      3640      Fas 1/0

R2#show cdp neighbors 
Capability Codes: R - Router, T - Trans Bridge, B - Source Route Bridge
                  S - Switch, H - Host, I - IGMP, r - Repeater

Device ID        Local Intrfce     Holdtme    Capability  Platform  Port ID
R3               Fas 1/0            164        R S I      3640      Fas 1/0

CDP can be used for troubleshooting the network but it’s recommended in the production network to disable it because CDP sometimes can be used as a major medium for hackers to get into the network.