MSM7xx Controllers Configuration Guide v6.4.0

23 LLDP
Overview
The IEEE 802.1AB Link Layer Discovery Protocol (LLDP) provides a standards-based method for
network devices to discover each other and exchange information about their capabilities. An
LLDP device advertises itself to adjacent (neighbor) devices by transmitting LLDP data packets on
all ports on which outbound LLDP is enabled, and reading LLDP advertisements from neighbor
devices on ports that are inbound LLDP-enabled. An LLDP enabled port receiving LLDP packets
inbound from neighbor devices stores the packet data in a Neighbor database (MIB).
LLDP information is used by network management tools to create accurate physical network
topologies by determining which devices are neighbors and through which ports they connect.
LLDP operates at layer 2 and requires an LLDP agent to be active on each network interface that
will send and receive LLDP advertisements. LLDP advertisements can contain a variable number of
TLV (type, length, value) information elements. Each TLV describes a single attribute of a device.
When an LLDP agent receives information from another device, it stores it locally in a special LLDP
MIB (management information base). This information can then be queried by other devices via
SNMP. For example, the HP ProCurve Manager software retrieves this information to build an
overview of a network and all its components.
NOTE: LLDP information is only sent/received on Ethernet links. LLDP information is not collected
from wireless devices connected to an AP.
LLDP-MED
(Only supported on the HP 517 or MSM317.)
LLDP provides the base capabilities for network devices, but was not considered sufficient for IP
telephony devices. As a result, in 2004, an initiative by Mitel, HP ProCurve, Avaya and Enterasys
was undertaken to enhance LLDP so that it could better support IP telephony devices. The
development of LLDP-Medium Endpoint Discovery (LLDP-MED) (ANSI/TIA-1057/D6) extended the
LLDP standard to support advanced features on the network edge for VoIP endpoint devices with
specialized capabilities and LLDP-MED standards-based functionality. The extensions to LLDP include
the specification of additional TLV (Type, Length, and Value) entries specifically for VoIP
management. LLDP-MED benefits include:
• Plug-and-play provisioning for MED-capable, VoIP endpoint devices.
• Simplified, vendor-independent management enabling different IP telephony systems to
interoperate on one network.
• Automatic deployment of convergence network policies that includes voice VLANs, Layer2/CoS
priority, and Layer 3/QoS priority.
• Configurable endpoint location data to support the Emergency Call Service (ECS) such as
Enhanced 911, 999 and 112.
• Detailed VoIP endpoint data inventory readable via SNMP from the switch.
• Power over Ethernet (PoE) status and troubleshooting support via SNMP.
• Support for IP telephony network troubleshooting of call quality issues via SNMP.
LLDP-MED endpoint devices are located at the network edge and communicate using the LLDP-MED
framework. Any LLDP-MED endpoint device belongs to one of the following three classes:
• Class 1 (Generic Endpoint Devices): These devices offer the basic LLDP discovery services,
network policy advertisement (VLAN ID, Layer 2/802.1p priority, and Layer 3/DSCP priority),
Overview 517