2
The types of supported LLDP agents vary with the bridge mode in which LLDP operates. LLDP
supports the following bridge modes: customer bridge (CB) and service bridge (SB).
• Customer bridge mode—LLDP supports nearest bridge agent, nearest non-TPMR bridge
agent, and nearest customer bridge agent. LLDP processes the LLDP frames with destination
MAC addresses for these agents and transparently transmits the LLDP frames with other
destination MAC addresses in VLANs.
• Service bridge mode—LLDP supports nearest bridge agent and nearest non-TPMR bridge
agent. LLDP processes the LLDP frames with destination MAC addresses for these agents and
transparently transmits the LLDP frames with other destination MAC addresses in VLANs.
LLDP frame formats
LLDP sends device information in LLDP frames. LLDP frames are encapsulated in Ethernet II or
Subnetwork Access Protocol (SNAP) format.
LLDP frame encapsulated in Ethernet II
Figure 2 Ethernet II-encapsulated LLDP frame
Table 1 Fields in an Ethernet II-encapsulated LLDP frame
Field Description
Destination MAC address
MAC address to which the LLDP frame is advertised. LLDP specifies
different multicast MAC addresses as destination MAC addresses for LLDP
frames destined for agents of different types. This helps distinguish between
LLDP frames sent and received by different agent types on the same
interface. The destination MAC address is fixed to one of the following
multicast MAC addresses:
• 0x0180-c200-000E for LLDP frames destined for nearest bridge
agents.
• 0x0180-c200-0000 for LLDP frames destined for nearest customer
bridge agents.
• 0x0180-c200-0003 for LLDP frames destined for nearest non-TPMR
bridge agents.
Source MAC address MAC address of the sending port.
Type Ethernet type for the upper-layer protocol. This field is 0x88CC for LLDP.
Data LLDPDU.
FCS
Frame check sequence, a 32-bit CRC value used to determine the validity of
the received Ethernet frame.
To Next Page
Loading...
Need help?
General