LLDP Function Operation Configuration
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9. LLDP Function Operation
Configuration
9.1
Introduction to LLDP Function
Link Layer Discovery Protocol (LLDP) is a new protocol defined in 802.1ab. It enables
neighbor devices to send notices of their own state to other devices, and enables all ports
of every device to store information about them. If necessary, the ports can also send
update information to the neighbor devices directly connected to them, and those
neighbor devices will store the information in standard SNMP MIBs. The network
management system can check the layer-
two connection state from MIB. LLDP won‘t
configure or control network elements or flows, but only report the configuration of
layer-two. Another content of 802.1ab is to utilizing the information provided by LLDP to
find the conflicts in layer-two. IEEE now uses the existing physical topology, interfaces
and Entity MIBs of IETF.
To simplify, LLDP is a neighbor discovery protocol. It defines a standard method for
Ethernet devices, such as switches, routers and WLAN access points, to enable them to
notify their existence to other nodes in the network and store the discovery information of
all neighbor devices. For example, the detail information of the device configuration and
discovery can both use this protocol to advertise.
In specific, LLDP defines a general advertisement information set, a transportation
advertisement protocol and a method to store the received advertisement information.
The device to advertise its own information can put multiple pieces of advertisement
information in one LAN data packet to transport. The type of transportation is the type
length value (TLV) field. All devices supporting LLDP have to support device ID and port
ID advertisement, but it is assumed that, most devices should also support system name,
system description and system performance advertisement. System name and system
description advertisement can also provide useful information for collecting network flow
data. System description advertisement can include data such as the full name of the
advertising device, hardware type of system, the version information of software operation
system and so on.
802.1AB Link Layer Discovery Protocol will make searching the problems in an
enterprise network an easier process and can strengthen the ability of network
management tools to discover and maintain accurate network topology structure.
Many kinds of network management software use ―Automated Discovery‖ function to