I do industrial controls so very familiar. IP is a lot of overhead that doesn't really do anything for the user in a tightly defined automation network local to a machine. EtherCAT goes a step lower and drops IP in favor of just sending Ethernet frames of type 0x88A4. It uses a unique ring topology. It does not use traditional switching or repeaters with the IO devices containing a special controller called the ESC, the EtherCAT Subordinate Controller. The master only needs a standard Ethernet controller. You can get cycle times in the 10's of microseconds allowing for up to 50khz update rates on IO devices. This allows you to do do high performance servo motor control where you close the current loop in the master CPU over 100mbit Ethernet and easily reach 10+ kHz update rates.

With FPGAs using commodity SFP or Ethernet PHY's you can certainly build stuff that runs circles around traditional Ethernet and associated overhead from protocols like IP.