Using Link Layer Discovery Protocol in Multivendor Networks
Link Layer Discovery Protocol (LLDP), standardized by the IEEE as part of 802.1ab, enables standardized discovery of nodes,
which in turn facilitates future applications of standard management tools such as Simple Network Management Protocol (SNMP)
in multivendor networks. Using standard management tools makes physical topology information available and helps network administrators
detect and correct network malfunctions and inconsistencies in configuration.
The Cisco implementation of LLDP is based on the IEEE 802.1ab standard.
Finding Feature Information
Your software release may not support all the features documented in this module. For the latest caveats and feature information,
see Bug Search Tool and the release notes for your platform and software release. To find information about the features documented in this module,
and to see a list of the releases in which each feature is supported, see the feature information table.
Use Cisco Feature Navigator to find information about platform support and Cisco software image support. To access Cisco Feature
Navigator, go to www.cisco.com/go/cfn. An account on Cisco.com is not required.
Information About Using Link Layer Discovery Protocol in Multivendor Networks
IEEE 802.1ab LLDP
IEEE 802.1ab Link Layer Discovery Protocol (LLDP) is an optional link layer protocol for network topology discovery in multivendor
networks. Discovery information includes device identifiers, port identifiers, versions, and other details. As a protocol
that aids network management, LLDP provides accurate network mapping, inventory data, and network troubleshooting information.
LLDP is unidirectional, operating only in an advertising mode. LLDP does not solicit information or monitor state changes
between LLDP nodes. LLDP periodically sends advertisements to a constrained multicast address. Devices supporting LLDP can
send information about themselves while they receive and record information about their neighbors. Additionally, devices can
choose to turn off the send or receive functions independently. Advertisements are sent out and received on every active and
enabled interface, allowing any device in a network to learn about all devices to which it is connected. Applications that
use this information include network topology discovery, inventory management, emergency services, VLAN assignment, and inline
LLDP and Cisco Discovery Protocol can operate on the same interface.
The figure below shows a high-level view of LLDP operating in a network node.
When you configure LLDP or Cisco Discovery Protocol location information on a per-port basis, remote devices can send Cisco
medianet location information to the switch. For more information, see the Using Cisco Discovery Protocol module.
Benefits of LLDP
Follows IEEE 802.1ab standard.
Enables interoperability among multivendor devices.
Facilitates troubleshooting of enterprise networks and uses standard network management tools.
Provides extension for applications such as VoIP.
How to Configure Link Layer Discovery Protocol in Multivendor Networks
Enabling and Disabling LLDP Globally
LLDP is disabled globally by default. This section describes the tasks for enabling and disabling LLDP globally.