Switches and VLANs

CDP

Also called Cisco Discovery Protocol, show cdp neighbors

Cisco's own discovery protocol, on by default on every Cisco device.

CDP does LLDP's job in Cisco's format: an 802.3 frame with an LLC/SNAP header (OUI 00000c, protocol 0x2000) to 01:00:0c:cc:cc:cc, carrying Device-ID, addresses, Port-ID, capabilities, software version and platform. It came first (1994); mixed networks use LLDP. show cdp neighbors detail reads the table; no cdp enable turns it off on a port.

See it on real machines

Learn it on real machines.