CDP (Cisco Discovery Protocol) is a proprietary Data Link Layer protocol implemented in Cisco networking equipment. It is primarily used to obtain IP addresses of neighboring devices and discover their platform information. CDP is also used to obtain information about the interfaces the access point uses. CDP runs only over the data link layer enabling two systems that support different network-layer protocols to learn about each other.
LLDP (Link Layer Discovery Protocol) provides a standard way for a controller or access point to advertise information about themselves to networked neighbors and store information they discover from their peers.
LLDP is neighbor discovery protocol that defines a method for network access devices using Ethernet connectivity to advertise information about them to peer devices on the same physical LAN and store information about the network. It allows a device to learn higher layer management and connection endpoint information from adjacent devices.
Using LLDP, an access point is able to advertise its own identification, capabilities and media-specific configuration information and learn the same information from connected peer devices.
LLDP information is sent in an Ethernet frame at a fixed interval. Each frame contains one m LLDP PDU (Link Layer Discovery Protocol Data Unit). A single LLDP PDU is transmitted in a single 802.3 Ethernet frame.