3Com 2928 User Guide - Page 253

Field Source MAC address Type Data FCS Description 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. The Ethernet type for the upper layer protocol. It is 0x88CC for LLDP. LLDP data. 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 0 15 31 Destination MAC address Source MAC address Type Data = LLDPU (n bytes) FCS The fields in the frame are described in Table 1-2: Table 1-2 Description of the fields in a SNAP encapsulated LLDPDU Field Destination MAC address Source MAC address Type Data FCS Description The MAC address to which the LLDPDU is advertised. It is fixed to 0x0180-C200-000E, a multicast 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. The SNAP-encoded LLDP Ethernet type for the upper layer protocol. It is 0xAAAA-0300-0000-88CC for LLDP. LLDP data unit. 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. Figure 1-3 An LLDPDU 1-2