HP Compaq Presario,Presario 1910, User Manual

Page: 244 / 578

231
Field Description
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 202 LLDPDU encapsulated in SNAP
Table 71 Description of the fields in a SNAP-encapsulated LLDPDU
Field Description
Destination MAC address
MAC address to which the LLDPDU 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-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 203 .
Figure 203 LLDPDU encapsulation format
An LLDPDU can carry up 28 types of TLVs, of which the chassis ID TLV, port ID TLV, Time to Live (TTL) TLV,
and end of LLDPDU TLV are mandatory TLVs that must be carried and other TLVs are optional.
TLVs
TLVs are type, length, and value sequences that carry information elements, where the type field identifies
the type of information, the length field indicates the length of the information field in octets, and the
value field contains the information itself.