Transmits and receives data, PHY encodes data frames, Ethernet PHY chip

 KSZ8721B Series 2.5 V 10/100 Base TX/FX Physical Layer Transceiver - LQFP-48

https://www.futureelectronics.com/p/semiconductors--comm-products--phy/ksz8721bl-tr-microchip-8951675