RGMII connection between PHY and MCU

[FreshmanNewbie]

I need to make a design with the KSZ9031RNXCC. For mechanical reasons we can’t do this on one PCB, my first idea was to connect the 2 PCB ( max 5cm from each other) with a flat cable. But what is the best approach?

ETH connecter => Flat Cable => KSZ => microcontroller or ETH connecter => KSZ =>Flat Cable => microcontroller

How to design the flat cable for the best signal conditions?

 

[FvM]

Single ended RGMII interface and clock connections are more ciritical than differential ethernet lines. I would use flat cable on the ethernet side.