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Configuring LLDP
Overview
In a heterogeneous network, a standard configuration exchange platform makes sure different types of
network devices from different vendors can discover one another, and exchange configuration for the
sake of interoperability and management.
The IETF drafted the Link Layer Discovery Protocol (LLDP) in IEEE 802.1AB. The protocol operates on the
data link layer to exchange device information between directly connected devices. With LLDP, a device
sends local device information, including its major functions, management IP address, device ID, and
port ID, as TLV (type, length, and value) triplets in LLDP Data Units (LLDPDUs) to the directly connected
devices. At the same time, the device stores the device information received in LLDPDUs sent from the
LLDP neighbors in a standard MIB. LLDP enables a network management system to quickly detect and
identify Layer 2 network topology changes.
For more information about MIBs, see "Configuring SNMP."
Basic concepts
LLDPDU formats
LLDP sends device information in LLDP data units (LLDPDUs). LLDPDUs are encapsulated in Ethernet II or
SNAP frames.
1. LLDPDUs encapsulated in Ethernet II
Figure 178 LLDPDU encapsulated in Ethernet II
Table 66 Description of the fields in an Ethernet II encapsulated LLDPDU
Field Descri
Destination MAC address
MAC address to which the LLDPDU is advertised. It is fixed to
0x0180-C200-000E, a multicast MAC address.
Source MAC address MAC address of the sending port.
Type Ethernet type for the upper layer protocol. It is 0x88CC for LLDP.
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