Ethernet has been widely adopted in industrial markets as a robust way to transmit signals. In these industrial markets the physical layer of the Ethernet system is subject to harsh environment that can stress the system as a whole. Surge transients are particularly dangerous for these system as they represent a large amount of power that is coupled onto the transmit and receive circuitry of the Ethernet physical layer. This document goes through the dangers of surge pulses in Ethernet applications showing why and what protection is needed to make sure the Ethernet controller can survive these transients.