Configuring LLDP

The Link Layer Discovery Profile (LLDP) is an IEEE-standard protocol for link layer discovery in Ethernet networks. It enables switches to advertise their identification, configuration and capabilities to neighboring devices, which then store the data in a MIB (Management Information Base). Link layer discovery enables a network management system to model the topology of the network by interrogating the MIB databases in the network devices.

LLDP is designed to enable directly-connected devices on the network to discover one another and receive various types of information, such as the connected system port, management IP, location of the switch and so on.

The LLDP protocol operates in L2 by sending Multicast frames from each port. These are referred to as Protocol Data Unit (PDU or LLDP PDU) and are processed by devices that are aware of the LLDP protocol.

The LLDP PDU contains TLVs (type-length-value tuples), which contain the information that the device sends. The types of TLVs to send can be configured in the LLDP Port Settings Page and in the LLDP MED Port Settings Page (for more information about MED, refer to the section below and also to the Setting LLDP MED Network Policy section).

The LLDP protocol has an extension called LLDP Media Endpoint Discovery (LLDP-MED), which provides additional information to/from VoIP phones, such as: in which VLAN to transmit, and the value of the VPT and the DSCP.

LLDP Configuration Workflow

The following are a set of sample actions that can be performed with the LLDP feature:

  1. Enable LLDP globally (disabled by default) and enter LLDP global parameters, such as time interval for sending LLDP updates, using the LLDP Properties Page.
  2. Configure LLDP per interface, using the LLDP Port Settings Page.
  3. Create LLDP MED network policies, using the LLDP MED Network Policy Page.
  4. Associate LLDP MED network policies to ports, using the LLDP MED Port Settings Page.
  5. Enable viewing of the LLDP information that was discovered from neighbors, such as: Local Port, system name, time to live, system description, system capabilities, using the LLDP Neighbors Information Page.
  6. View LLDP-related statistical information per interface, using the LLDP Statistics Page.
  7. Display overloading information, using the LLDP Overloading Page.