8.3.17.0 - Force10 Networks

Link Layer Discovery Protocol (LLDP)
14
An Aggregator auto-configures to support the link layer discovery protocol (LLDP) for the auto-discovery
of network devices. You can use CLI commands to display acquired LLDP information, clear LLDP
counters, and debug LACP operation.
Overview
LLDP—defined by IEEE 802.1AB—is a protocol that enables a local area network (LAN) device to
advertise its configuration and receive configuration information from adjacent LLDP-enabled LAN
infrastructure devices. The collected information is stored in a management information base (MIB) on
each device, and is accessible via a simple network management protocol (SNMP).
Protocol Data Units
Configuration information is exchanged in the form of type, length, value (TLV) segments. Figure 14-1
shows the Chassis ID TLV.
• Type—Indicates the type of field that a part of the message represents.
• Length—Indicates the size of the value field (in bytes).
• Value—Indicates the data for this part of the message.
Figure 14-1. Type, Length, Value (TLV) Segment
TLV Type
(1-127)
TLV Header
7 bits 9 bits
TLV Length Value
0-511 octets
Chassis ID Sub-type
fnC0057mp
TLVs are encapsulated in a frame called an LLDP data unit (LLDPDU) (Figure 14-2), which is transmitted
from one LLDP-enabled device to its LLDP-enabled neighbors. LLDP is a one-way protocol.
LLDP-enabled devices (LLDP agents) can transmit and/or receive advertisements, but they cannot solicit
and do not respond to advertisements.
Chassis ID
1 octet 1- 255 octets
Link Layer Discovery Protocol (LLDP) | 165