Earlier this year I took a closer look again at the Zyxel GS1900-8 switch. Last time I mainly looked at the firmware itself, however this time I took a closer look at a different vector to test this device. Link Layer Discovery Protocol (LLDP) Based on an educated guess I started poking around the LLDP pages on the web interface. LLDP is a layer 2 network protocol described in IEEE 802.