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Link Layer Discovery Protocol (LLDP)
Issue 2 December 2007 101
Link Layer Discovery Protocol (LLDP)
Link Layer Discovery Protocol (LLDP) is an open standards layer 2 protocol IP Telephones use
to advertise their identity and capabilities and to receive administration from an LLDP server.
LAN equipment can use LLDP to manage power, administer VLANs, and provide some
administration.
The transmission and reception of LLDP is specified in IEEE 802.1AB-2005. The 9600 Series
IP Telephones use Type-Length-Value (TLV) elements specified in IEEE 802.1AB-2005, TIA
TR-41 Committee - Media Endpoint Discovery (LLDP-MED, ANSI/TIA-1057), and Proprietary
elements. LLDP Data Units (LLDPDUs) are sent to the LLDP Multicast MAC address
(01:80:c2:00:00:0e).
9600 Series IP Telephones running SIP Release 2.0 software support IEEE 802.1AB if the
value of the configuration parameter LLDP_ENABLED is "1" (On) or "2" (Auto). If the value of
LLDP_ENABLED is “0” (off), the transmission and reception of Link Layer Discovery Protocol
(LLDP) is not supported. When the value of LLDP_ENABLED is “2”, the transmission of LLDP
frames will not begin until or unless an LLDP frame is received, and the first LLDP frame will be
transmitted within 2 seconds after the first LLDP frame is received. Once transmission begins,
an LLDPDU will be transmitted every 30 seconds.
Note:
Note: There could be a delay of up to 30 seconds in telephone initialization if the file
server address is delivered by LLDP and not by DHCP.
These telephones:
● do not support LLDP on the secondary Ethernet interface.
● will not forward frames received with the 802.1AB LLDP group multicast address as the
destination MAC address between the Ethernet line interface and the secondary Ethernet
interface.
A 9600 Series IP Telephone initiates LLDP after receiving an LLDPDU message from an
appropriate system. Once initiated, the telephones send an LLDPDU every 30 seconds with the
following contents:
Table 13: LLDPDU Transmitted by 9600 Series SIP IP Telephones
Category TLV Name (Type) TLV Info String (Value)
Basic Mandatory Chassis ID IPADD of telephone, IANA Address Family
Numbers enumeration value for IPv4, or
subtype 5:Network address.
Basic Mandatory Port ID MAC address of the telephone.
Basic Mandatory Time-To-Live 120 seconds.
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