LLDP packets transport TLVs to other
network devices (see LLDP Packet Format).
The LLDP packet contains the destination multicast address, the source MAC
address, the LLDP EtherType, the LLDPDU data (which contains the TLVs), and a frame
check sequence (FCS). The LLDP multicast address is defined as 01:80:C2:00:00:0E, and
the EtherType is defined as 0x88CC.
LLDP Packet Format
The following characteristics apply to LLDP packets:
They are IEEE 802.3 Ethernet frames.
The frames are sent as untagged frames.
The frames are sent with a link-local-assigned multicast address
as the destination address.
The STP state of the port does not
affect the transmission of LLDP frames.
The length of the packet cannot exceed 1500 bytes. As you add TLVs, you
increase the length of the LLDP frame. When you reach 1500 bytes, the remaining TLVs are
dropped. We recommend that you advertise information regarding only one or two VLANs on
the LLDP port, to avoid dropped TLVs.
If the system drops TLVs because of exceeded length, the system logs a
message to the EMS and the show lldp
statistics command shows this information under the Tx Length
Exceeded field.
Note
The LLDPDU maximum size is 1500 bytes, even with
jumbo frames enabled. TLVs that exceed this limit are dropped.
