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An LLDPDU can carry up to 28 types of TLVs. The chassis ID TLV, port ID TLV, TTL TLV, and end of LLDPDU
TLV (end TLV in the figure) are mandatory TLVs that must be carried. Other TLVs are optional.
TLVs
TLVs are type, length, and value sequences that carry information elements, where the type field identifies
the type of information, the length field indicates the length of the information field in octets, and the
value field contains the information itself.
LLDPDU TLVs fall into the following categories:
Basic management TLVs
•
Organizationally (IEEE 802.1 and IEEE 802.3) specific TLVs
•
•
LLDP-MED (media endpoint discovery) TLVs
Basic management TLVs are essential to device management. Organizationally specific TLVs and
LLDP-MED TLVs are used for enhanced device management, and are defined by standardization or other
organizations and thus are optional to LLDPDUs.
Basic management TLVs
1.
Table 19
must be included in every LLDPDU.
Table 21 Basic LLDP TLVs
Type
Chassis ID
Port ID
Time To Live
End of LLDPDU
Port Description
System Name
System Description
System Capabilities
Management Address
IEEE 802.1 organizationally specific TLVs
2.
Table 22 IEEE 802.1 organizationally specific TLVs
Type
Port VLAN ID
Port And Protocol VLAN ID
VLAN Name
lists the basic management TLV types. Some of them are mandatory to LLDPDUs, and
Description
Bridge MAC address of the sending device
ID of the sending port.
If MED TLVs are included in the LLDPDU, the port ID TLV carries
the MAC address of the sending port or the bridge MAC in case
the port does not have a MAC address. If no MED TLVs are
included, the port ID TLV carries the port name.
Life of the transmitted information on the receiving device
Marks the end of the TLV sequence in the LLDPDU
Port description of the sending port
Name of the sending device
Description of the sending device
Identifies the primary functions of the sending device and the
primary functions that have been enabled
Management address used to reach higher level entities to assist
discovery by network management, and the interface number
and object identifier (OID) associated with the address
Description
PVID of the sending port
Port and protocol VLAN IDs
A specific VLAN name on the port
135
Remarks
Mandatory
Optional
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