Dell PowerEdge XL 5133-4 MXL 10/40GbE Switch IO Module FTOS Command Reference - Page 181

14 Link Layer Discovery Protocol (LLDP) An Aggregator auto-configures to support the link layer discovery protocol (LLDP) for the auto-discovery of network devices. You can use CLI commands to display acquired LLDP information, clear LLDP counters, and debug LACP operation. Overview LLDP-defined by IEEE 802.1AB-is a protocol that enables a local area network (LAN) device to advertise its configuration and receive configuration information from adjacent LLDP-enabled LAN infrastructure devices. The collected information is stored in a management information base (MIB) on each device, and is accessible via a simple network management protocol (SNMP). Protocol Data Units Configuration information is exchanged in the form of type, length, value (TLV) segments. Figure 14-1 shows the Chassis ID TLV. • Type-Indicates the type of field that a part of the message represents. • Length-Indicates the size of the value field (in bytes). • Value-Indicates the data for this part of the message. Figure 14-1. Type, Length, Value (TLV) Segment TLV Header TLV Type (1-127) 7 bits TLV Length Value 9 bits 0-511 octets Chassis ID Sub-type Chassis ID 1 octet 1- 255 octets fnC0057mp TLVs are encapsulated in a frame called an LLDP data unit (LLDPDU) (Figure 14-2), which is transmitted from one LLDP-enabled device to its LLDP-enabled neighbors. LLDP is a one-way protocol. LLDP-enabled devices (LLDP agents) can transmit and/or receive advertisements, but they cannot solicit and do not respond to advertisements. Link Layer Discovery Protocol (LLDP) | 167