Lldp Messages; Overview - HP ProCurve Secure Router 7203 dl Advanced Management And Configuration Manual

Link Layer Discovery Protocol

Overview

Switch
Switch
12-2
Overview
Routing protocols allow routers to learn about each other dynamically as a
network expands and changes. However, these protocols run over Layer 3 of
the Open Systems Interconnection (OSI) model. Devices such as switches,
which operate on Layer 2, do not participate.
Networks expand all the time; switches are moved, and new ones are added.
Devices need to stay up to date on these changes. Link Layer Discovery
Protocol (LLDP), which runs over OSI Layer 2, allows locally attached devices
in a network, such as switches and routers, to advertise information about
themselves to listening devices. (See Figure 12-1.) Because devices continu-
ally broadcast and listen for LLDP messages, they can discover when a new
device is added or one removed. In this way, they maintain an accurate picture
of a dynamic network.
LLDP
messages
Router
LLDP
messages
Figure 12-1. LLDP
LLDP
LLDP functions over any Data Link Layer network. Nodes transmit informa-
tion about themselves and listen for information about the devices on each
connection. With this information, they compile a picture of the network and
of the neighbors that they can reach.
Nodes identify neighbors according to the information (such as MAC address
and system name) they receive in LLDP messages. LLDP messages also
include a network address where a management process such as a Simple
Network Management Protocol (SNMP) server can reach the endpoint.
LLDP
messages
Routing
protocols
Router
LLDP
messages
Switch