The EGS7228P supports the iEEE 802.1AB Link Layer Discovery Protocol (LLDP) not the CDP since the LLDP is a vendor-neutral link layer protocol unlike CDP which is proprietary for Cisco.
Link Layer Discovery Protocol (LLDP) is the IEEE 802.1AB standard for Switches to advertise their identity, major capabilities, and neighbors on the 802 LAN. LLDP allows users to views the discovered information to identify system topology and detect faulty configurations on theLAN. LLDP is essentially a neighbor discovery protocol that uses Ethernet connectivity to advertise information to devices on the same LAN and store information about the network. The information transmitted in LLDP advertisements flow in one direction only; from one device to its neighbors. This information allows the device to quickly identify variety of other devices, resulting in a LAN that interoperates smoothly and efficiently.
LLDP transmits information as packets called LLDP Data Units (LLDPDUs). A single LLDP Protocol Data Unit (LLDP PDU) is transmitted within a single 802.3 Ethernetframe. A basic LLDPDU consists of a set of TypeLength-Value elements (TLV), each of which contains information about the device. A single LLDPDU contains multiple TLVs. TLVs are short information elements that communicate complex data. Each TLV advertises a single type of information.