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3com 2928 User Guide

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1-2 
Field 
Description 
Source MAC address 
The 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 
The Ethernet type for the upper layer protocol. It is 0x88CC for LLDP. 
Data 
LLDP data.  
FCS 
Frame check sequence, a 32-bit CRC value used to determine the 
validity of the received Ethernet frame.  
 
2)  LLDPDUs encapsulated in SNAP 
Figure 1-2 
LLDPDU encapsulated in SNAP 
 
Data = LLDPU
(n bytes)
0
Destination MAC address
Source MAC address
Type
15
31
FCS
 
 
The fields in the frame are described in 
:  
Table 1-2 
Description of the fields in a SNAP encapsulated LLDPDU 
Field 
Description 
Destination MAC address  The MAC address to which the LLDPDU is advertised. It is fixed to 
0x0180-C200-000E, a multicast MAC address.  
Source MAC address 
The 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 
The SNAP-encoded LLDP Ethernet type for the upper layer protocol. It 
is 0xAAAA-0300-0000-88CC for LLDP.  
Data 
LLDP data unit.  
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 type, length, and value 
(TLV) sequences, each carrying a type of device information, as shown in 
. 
Figure 1-3 
An LLDPDU