Understanding LLDP and LLDP-MED
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These organizationally specific LLDP TLVs are also advertised to support LLDP-MED.
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A switch stack appears as a single switch in the network. Therefore, LLDP discovers the switch stack,
Note
not the individual stack members.
LLDP-MED
LLDP for Media Endpoint Devices (LLDP-MED) is an extension to LLDP that operates between
endpoint devices such as IP phones and network devices such as switches. It specifically provides
support for voice over IP (VoIP) applications and provides additional TLVs for capabilities discovery,
network policy, Power over Ethernet, inventory management and location information. By default, all
LLDP-MED TLVs are enabled.
LLDP-MED supports these TLVs:
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Catalyst 2928 Switch Software Configuration Guide
24-2
System capabilities TLV
Management address TLV
Port VLAN ID TLV ((IEEE 802.1 organizationally specific TLVs)
MAC/PHY configuration/status TLV(IEEE 802.3 organizationally specific TLVs)
LLDP-MED capabilities TLV
Allows LLDP-MED endpoints to determine the capabilities that the connected device supports and
has enabled.
Network policy TLV
Allows both network connectivity devices and endpoints to advertise VLAN configurations and
associated Layer 2 and Layer 3 attributes for the specific application on that port. For example, the
switch can notify a phone of the VLAN number that it should use. The phone can connect to any
switch, obtain its VLAN number, and then start communicating with the call control.
By defining a network-policy profile TLV, you can create a profile for voice and voice-signalling by
specifying the values for VLAN, class of service (CoS), differentiated services code point (DSCP),
and tagging mode. These profile attributes are then maintained centrally on the switch and
propagated to the phone.
Power management TLV
Enables advanced power management between LLDP-MED endpoint and network connectivity
devices. Allows switches and phones to convey power information, such as how the device is
powered, power priority, and how much power the device needs.
Inventory management TLV
Allows an endpoint to send detailed inventory information about itself to the switch, including
information hardware revision, firmware version, software version, serial number, manufacturer
name, model name, and asset ID TLV.
Location TLV
Provides location information from the switch to the endpoint device. The location TLV can send
this information:
Civic location information
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Provides the civic address information and postal information. Examples of civic location
information are street address, road name, and postal community name information.
Chapter 24
Configuring LLDP and LLDP-MED
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