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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.
The Link Layer Discovery Protocol (LLDP) is specified 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 as TLV (type, length, and value) triplets in LLDP Data Units
(LLDPDUs) to the directly connected devices. Local device information includes its system
capabilities, management IP address, device ID, port ID, and so on. The device stores the device
information in LLDPDUs 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
LLDP frame formats
LLDP sends device information in LLDP frames. LLDP frames are encapsulated in Ethernet II or
SNAP frames.
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LLDP frames encapsulated in Ethernet II
Figure 172 LLDP frame encapsulated in Ethernet II
Table 69 Fields in an Ethernet II encapsulated LLDP frame
Field Description
Destination MAC address
MAC address to which the LLDP frame 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.
Data LLDPDU.
FCS
Frame check sequence, a 32-bit CRC value used to determine the
validity of the received Ethernet frame.
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LLDP frames encapsulated in SNAP