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Understanding LLDP and LLDP-MED on a Junos Fusion

This topic describes Link Layer Discovery Protocol (LLDP) and Link Layer Discovery Protocol–Media Endpoint Discovery (LLDP-MED) in a Junos Fusion.

This topic covers:

LLDP and LLDP-MED in a Junos Fusion Overview

LLDP and LLDP-MED are used to learn and distribute device information on network links. The information enables the switch to quickly identify a variety of devices, resulting in a LAN that interoperates smoothly and efficiently.

LLDP-capable devices transmit information in type, length, and value (TLV) messages to neighbor devices. Device information can include information such as chassis and port identification and system name and system capabilities. The TLVs leverage this information from parameters that have already been configured in the Junos operating system (Junos OS).

Many LLDP and LLDP-MED concepts for standalone EX Series switches that support the features also apply to LLDP and LLDP-MED on Junos Fusion. See Understanding LLDP and LLDP-MED on EX Series Switches for a detailed overview of LLDP and LLDP-MED on standalone EX Series switches.


LLDP-MED goes one step further than LLDP, exchanging IP-telephony messages between the switch and the IP telephone. LLDP-MED is an important access layer switch feature that is supported in a Junos Fusion despite not being supported on a standalone EX9200 switch.

Understanding LLDP and LLDP-MED Configuration and Traffic Handling in a Junos Fusion

LLDP and LLDP-MED traffic is generally handled the same in a Junos Fusion or a standalone series switch. LLDP and LLDP-MED configuration on an extended port in a Junos Fusion is identical for a standalone EX Series switch. See Configuring LLDP (CLI Procedure) or Configuring LLDP-MED (CLI Procedure).

The following specifications apply to the device information transmitted by LLDP and LLDP-MED in a Junos Fusion topology with two or more aggregation devices:

  • Management address TLVs are merged into a single packet in such a way that the packet contains two or more management address TLVs.

  • The SNMP index used as the port ID TLV is derived so that all aggregation devices receive the same index value for port IDs of extended ports.

  • The system name for extended ports is the configured redundancy group name. A redundancy group has to be configured in order to enable a topology with two or more aggregation devices.

  • The chassis ID is the same for all aggregation devices. If a system MAC address is defined for the redundancy group, is it used as the chassis ID. The system MAC address is configured using the set chassis satellite-management redundancy-groups redundancy-group-name system-mac-address system-mac-address command. If the system MAC is not configured, the chassis ID is the default MAC address, which is 00:00:00:00:00:01.

    Best Practice:

    We recommend specifying a system MAC address if you are running LLDP or LLCP-MED traffic in your Junos Fusion topology.