Understanding Lldp-Med - Cisco WS-C2960-24LC-S Software Configuration Manual

Understanding LLDP and LLDP-MED
LLDP supports a set of attributes that it uses to discover neighbor devices. These attributes contain type,
length, and value descriptions and are referred to as TLVs. LLDP supported devices can use TLVs to
receive and send information to their neighbors. Details such as configuration information, device
capabilities, and device identity can be advertised using this protocol.
The switch supports these basic management TLVs. These are mandatory LLDP TLVs.
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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,
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not the individual stack members.

Understanding 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 2960 Switch Software Configuration Guide
21-2
Port description TLV
System name TLV
System description TLV
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
what capabilities the device 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 into any
switch, obtain its VLAN number, and then start communicating with the call control
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.
Chapter 21 Configuring LLDP and LLDP-MED
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