LLDP is enabled on all ports by default. When you enable LLDP on one or more ports, you select whether the ports will only transmit LLDP messages, only receive the messages, or both transmit and receive LLDP messages.
After you enable LLDP, the following TLVs are automatically added to the LLDPDU:
All of these, except the system description, are mandated by the 802.1ab standard and cannot be configured. For information on changing the system description TLV advertisement, see System Description TLV.