Dell EMC SmartFabric OS10 User Guide Release 10.5.1

Link Layer Discovery Protocol

LLDP is a one-way protocol that enables network devices on a local area network (LAN) to discover and advertise its capabilities to adjacent LAN devices. LLDP devices advertise its capabilities in the form of LLDP data units (LLDPDUs).

LLDP-MED is an LLDP enhancement that enables endpoint devices and network connected devices to advertise their characteristics and configuration information.

LLDP-MED network connected devices such as switches provide access to the IEEE 802-based LAN infrastructure for LLDP-MED endpoint devices, such as IP phones. OS10 switch acts as an LLDP-MED network connected device.

• By default, LLDP and LLDP-MED are enabled on the interfaces.
  NOTE: You cannot configure LLDP-MED on the management interface.
• An LLDP-enabled interface supports up to eight neighbors. OS10 switch supports a maximum of 250 neighbors per system.
• OS10 switches periodically transmit LLDPDUs. The default transmission interval is 30 seconds.
• OS10 switches receive LLDPDU information from a neighbor. The information expires after a specific amount of time, called time to live (TTL). The default TTL value is 120 seconds.
• OS10 switches allow LLDPDUs in spanning-tree blocked ports.
• OS10 switches do not allow LLDPDUs in 802.1X-controlled ports until the connected device is authenticated.

LLDPDUs include mandatory and optional TLVs. Each LLDPDU starts with three mandatory TLVs, zero or more optional TLVs, and end of LLDPDU TLV.