Connect ATmega IC to Ethernet MAC Layer Interface

Hi, I’m looking to connect an ATMEGA644 to an Ethernet MAC (not PHY). Is anyone aware of how to do this? I know I can use a wiznet chip like a W5500 to use Ethernet at the PHY level but I’m looking to connect at the MAC layer. I’m attempting to make a PCB that has an Ethernet switch IC on the same board as the ATMEGA IC. A lot of Ethernet switch ICs (haven’t decided on one yet) have several PHY interfaces and one MAC interface which can be used to connect to something locally on the same PCB. I’m just not sure how to do it as all the Ethernet ICs I’ve been looking at only have a PHY interface that can’t be bypassed (wiznet). I could do a PHY to PHY interface on the same board but I believe I would need a transformer or magnetics? Any help would be appreciated. Thanks.

Update: I may have found a solution. The Wiznet W3150A+ chip supplies a MAC interface instead of a PHY. A library does not seem to exist for this chip but it may possibly be compatible with the Arduino W5100 Library.

with W5500 you can use MAC level, not PHY. enc28j60 has only MAC level.

esp8266 WiFi library can use W5500 and enc28j60 as additional interfaces for the LwIP TCP/IP stack