LLDP configuration
Background
In a heterogeneous network, it is important that different types of network devices from different vendors can discover one other and exchange configuration for interoperability and management sake. To ensure compatibility, a standard configuration exchange platform was created.
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 as TLV (type, length, and value) triplets in LLDP Data Units (LLDPDUs) to the directly connected devices, and at the same time, stores the device information received in LLDPDUs sent from the LLDP neighbors in a standard management information base (MIB). It allows a network management system to quickly detect and identify Layer 2 network topology changes.
Basic concepts
LLDPDUs
LLDP sends device information in LLDPDUs. LLDPDUs are encapsulated in Ethernet II or Subnetwork Access Protocol (SNAP) frames.
Table 56 Ethernet
b.Ethernet
2.Fields in an Ethernet II encapsulated LLDPDU
Field | Description | |
Destination MAC address | The MAC address to which the LLDPDU is advertised. It is fixed to | |
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Source MAC address | The MAC address of the sending port. If the port does not have a MAC | |
address, the MAC address of the sending bridge is used. | ||
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Type | The Ethernet type for the upper layer protocol. It is 0x88CC for LLDP. | |
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Data | LLDPDU. | |
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| 218 |