314 | Link Layer Discovery Protocol (LLDP)
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TLVs are encapsulated in a frame called an LLDP data unit (LLDPDU) (Figure 18-2), which is transmitted
from one LLDP-enabled device to its LLDP-enabled neighbors. LLDP is a one-way protocol.
LLDP-enabled devices (LLDP agents) can transmit and/or receive advertisements, but they cannot solicit
and do not respond to advertisements.
There are five types of TLVs (Table 18-1). All types are mandatory in the construction of an LLDPDU
except Optional TLVs. You can configure the inclusion of individual Optional TLVs.
Figure 18-2. LLDPDU Frame
Optional TLVs
The Dell Force10 operating software (FTOS) supports the following optional TLVs:
•
Management TLVs
• IEEE 802.1 and 802.3 Organizationally Specific TLVs
• TIA-1057 Organizationally Specific TLVs
Table 18-1. Type, Length, Value (TLV) Types
Type TLV Description
0 End of LLDPDU Marks the end of an LLDPDU.
1 Chassis ID An administratively assigned name that identifies the LLDP agent.
2 Port ID An administratively assigned name that identifies a port through which TLVs are sent
and received.
3 Time to Live A value that tells the receiving agent how long the information contained in the TLV
Value field is valid.
— Optional Includes sub-types of TLVs that advertise specific configuration information. These
sub-types are Management TLVs, IEEE 802.1, IEEE 802.3, and TIA-1057
Organizationally Specific TLVs.
TLV 1
Chassis ID
Preamble
Start Frame
Delimiter
Destination MAC
(01:80:C2:00:00:0E)
Source MAC
Ethernet Type
(0x88CC)
LLDPDU
Padding
FCS
TLV 2
Port ID
TLV 3
Port Description
TLV 4
System Name
TLV 5
System Description
TLV 6
System Capabilities
TLV 7
Management Addr
TLV 0
End of LLDPDU
TLV 127
Organizationally Specific
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