Technical Tip: How to get LLDP frames from FortiAP

Description

This article describes the steps to get the LLDP that FortiAP receives from its Ethernet connection.

Scope

FortiAP E, F, G, K series.

Solution

To capture LLDP packets from the FortiAP perspective, a sniffer must be configured on FortiAP's CLI.

diag_sniffer any "ether proto 0x88CC" 6

LLDP frame capture on FortiAP:

This output can be converted to a .pcap file for analysis in Wireshark or other protocol analyzer software. See Technical Tip: How to import 'diagnose sniffer packet' data to WireShark.

To avoid seeing the full packet, set the filter to 4:

diag_sniffer any "ether proto 0x88CC" 4

Note that FortiAP will send an LLDP frame every 30 seconds to its peer. In this case, the FortiAP 431F used for the test was connected to a FortiSwitch 124F using the LLDP profile 'default-auto-isl', the FortiAP is receiving LLDP frames every 3 seconds from the FortiSwitch.

In the FortiAP CLI, it is also possible to visualize the full LLDP information received from its peer with the command below:

lldpctl