HP A5120 EI Series Configuration Manual page 177

Figure 56 LLDPDU encapsulation format
Chassis ID TLV
An LLDPDU can carry up to 28 types of TLVs. Mandatory TLVs include Chassis ID TLV, Port ID TLV, Time To
Live TLV, and End of LLDPDU TLV. Other TLVs are optional.
TLVs
TLVs are type, length, and value sequences that carry information elements. The type field identifies the
type of information, the length field measures the length of the information field in octets, and the value
field contains the information itself.
LLDPDU TLVs fall into the categories of basic management TLVs, organizationally (IEEE 802.1 and IEEE
802.3) specific TLVs, and 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; they are defined by standardization or other organizations and are
optional to LLDPDUs.
Basic management TLVs
1.
Table 21 lists the basic management TLV types. Some of them are mandatory to LLDPDUs, that is, must be
included in every LLDPDU.
Table 23 Basic management 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 24 IEEE 802.1 organizationally specific TLVs
Type
Port VLAN ID
Port ID TLV Time To Live TLV
Description
Specifies the bridge MAC address of the sending device
Specifies the ID of the sending port
If the LLDPDU carries LLDP-MED TLVs, the port ID TLV carries the
MAC address of the sending port or the bridge MAC if the port
does not have a MAC address. If the LLDPDU carries no LLDP-
MED TLVs, the port ID TLV carries the port name.
Specifies the life of the transmitted information on the receiving
device
Marks the end of the TLV sequence in the LLDPDU
Specifies the port description of the sending port
Specifies the assigned name of the sending device
Specifies the description of the sending device
Identifies the primary functions of the sending device and the
enabled primary functions
Specifies the management address, and the interface number
and OID (object identifier) associated with the address
Description
Specifies the port's VLAN identifier (PVID). An LLDPDU carries only one TLV
of this type.
Optional TLV ... Optional TLV
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End of LLDPDU TLV
Remarks
Mandatory
Optional