Field

Data

FCS

Description

LLDPDU.

Frame check sequence, a 32-bit CRC value used to determine the validity of the received Ethernet frame.

•LLDP frames encapsulated in SNAP

Figure 196 LLDP frame encapsulated in SNAP

Table 70 Fields in a SNAP-encapsulated LLDP frame

Field

Description

Destination MAC address

MAC address to which the LLDP frame is advertised. It is fixed to

0x0180-C200-000E, a multicast MAC address.

 

 

 

Source MAC address

MAC address of the sending port. If the port does not have a MAC

address, the MAC address of the sending bridge is used.

 

 

 

Type

SNAP type for the upper layer protocol. It is

0xAAAA-0300-0000-88CC for LLDP.

 

 

 

Data

LLDPDU.

 

 

FCS

Frame check sequence, a 32-bit CRC value used to determine the

validity of the received Ethernet frame.

 

 

 

LLDPDUs

LLDP uses LLDPDUs to exchange information. An LLDPDU comprises multiple TLVs. Each TLV carries a type of device information, as shown in Figure 197.

Figure 197 LLDPDU encapsulation format

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

A TLV is an information element that contains the type, length, and value fields.

LLDPDU TLVs include the following categories:

218