Brocade FastIron Ethernet Switch Administration Guide - Manual (Page 168)

LLDP-MED class
An LLDP-MED class specifies an Endpoint type and its capabilities. An Endpoint can belong to one of
three LLDP-MED class types:
• Class 1 (Generic endpoint) - A Class 1 Endpoint requires basic LLDP discovery services, but does
not support IP media nor does it act as an end-user communication appliance. A Class 1 Endpoint
can be an IP communications controller, other communication-related server, or other device
requiring basic LLDP discovery services.
• Class 2 (Media endpoint) - A Class 2 Endpoint supports media streams and may or may not be
associated with a particular end user. Device capabilities include media streaming, as well as all of
the capabilities defined for Class 1 Endpoints. A Class 2 Endpoint can be a voice/media gateway,
conference, bridge, media server, etc.
• Class 3 (Communication endpoint) - A Class 3 Endpoint supports end user IP communication.
Capabilities include aspects related to end user devices, as well as all of the capabilities defined for
Class 1 and Class 2 Endpoints. A Class 3 Endpoint can be an IP telephone, softphone (PC-based
phone), or other communication device that directly supports the end user.
Discovery services defined in Class 3 include location identifier (ECS/E911) information and inventory
management.
The LLDP-MED device class is advertised when LLDP-MED is enabled on a port.
General LLDP operating principles
LLDP and LLDP-MED use the services of the Data Link sublayers, Logical Link Control and Media
Access Control, to transmit and receive information to and from other LLDP Agents (protocol entities
that implement LLDP).
LLDP is a one-way protocol. An LLDP agent can transmit and receive information to and from another
LLDP agent located on an adjacent device, but it cannot solicit information from another LLDP agent,
nor can it acknowledge information received from another LLDP agent.
LLDP operating modes
When LLDP is enabled on a global basis, by default, each port on the Brocade device will be capable
of transmitting and receiving LLDP packets. You can disable a port’s ability to transmit and receive
LLDP packets, or change the operating mode to one of the following:
• Transmit LLDP information only
• Receive LLDP information only
LLDP transmit mode
An LLDP agent sends LLDP packets to adjacent LLDP-enabled devices. The LLDP packets contain
information about the transmitting device and port.
An LLDP agent initiates the transmission of LLDP packets whenever the transmit countdown timing
counter expires, or whenever LLDP information has changed. When a transmit cycle is initiated, the
LLDP manager extracts the MIB objects and formats this information into TLVs. The TLVs are inserted
into an LLDPDU, addressing parameters are prepended to the LLDPDU, and the information is sent
out LLDP-enabled ports to adjacent LLDP-enabled devices.
LLDP-MED class
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