What is LLDP ?
The Link Layer Discovery Protocol (LLDP), standardized as 802.1AB, is a standardized network discovery protocol aimed to replace a wide variety of propietary protoclos such as Cisco CDP, Nortel discovery protocol, ... It helps network administrators to identify the neighbors devices (including remote ports) of the device they are configuring. As a link-layer protocol, LLDP works without needing a valid IP configuration on the devices.
LLDP show commands available in Packet Tracer 7.3
The show lldp IOS command displays general information about the state of LLDP protocol and LLDP configured timers.
Router#show lldp Global LLDP Information: Status: ACTIVE LLDP advertisements are sent every 30 seconds LLDP hold time advertised is 120 seconds LLDP interface reinitialisation delay is 2 seconds
show lldp neighbors
The show lldp neighbors command display details about LLDP discovered neighbors, including device name, local interface on which the device has been discovered, and remote network interface.
Router#show lldp neighbors Capability codes: (R) Router, (B) Bridge, (T) Telephone, (C) DOCSIS Cable Device (W) WLAN Access Point, (P) Repeater, (S) Station, (O) Other Device ID Local Intf Hold-time Capability Port ID Router Fa0/0 120 R Fa0/0 Switch Fa0/0 120 B Fa0/1 Total entries displayed: 2
show lldp neighbors detail
Router#show lldp neighbors detail ------------------------------------------------ Chassis id: 0001.C916.6501 Port id: Fa0/0 Port Description: FastEthernet0/0 System Name: Router System Description: Cisco IOS Software, 1841 Software (C1841-ADVIPSERVICESK9-M), Version 12.4(15)T1, RELEASE SOFTWARE (fc2) Technical Support: http://www.cisco.com/techsupport Copyright (c) 1986-2007 by Cisco Systems, Inc. Compiled Wed 18-Jul-07 04:52 by pt_team Time remaining: 90 seconds System Capabilities: R Enabled Capabilities: R Management Addresses - not advertised Auto Negotiation - supported, enabled Physical media capabilities: 100baseT(HD) Media Attachment Unit type: 10 Vlan ID: 1 ------------------------------------------------ Chassis id: 00D0.FFE9.B901 Port id: Fa0/1 Port Description: FastEthernet0/1 System Name: Switch System Description: Cisco IOS Software, C2960 Software (C2960-LANBASE-M), Version 12.2(25)FX, RELEASE SOFTWARE (fc1) Copyright (c) 1986-2005 by Cisco Systems, Inc. Compiled Wed 12-Oct-05 22:05 by pt_team Time remaining: 90 seconds System Capabilities: B Enabled Capabilities: B Management Addresses - not advertised Auto Negotiation - supported, enabled Physical media capabilities: 100baseT(HD) 1000baseT(HD) Media Attachment Unit type: 10 Vlan ID: 1 Total entries displayed: 2 Router#
Configure and use LLDP to discover network devices
LLDP can ge globally [de)activated using the [no] lldp run global configuration command. At the network interface, LLDP emission or reception can be configured using the [no] lldp transmit and the [no] lldp receive commands.