PHY back to back connections

[FreshmanNewbie]

I'm planning to use this Switch IC connected to another another switch ic which is the same part number. When connecting these devices in back to back mode with RGMII interface between then, I need to define which switch is PHY and which would be MAC right?

In that case, can someone tell me how to do it? In the datasheet, mentioned in page 12, I don't see a strap option that can help to identify this switch as PHY or MAC.

In the RGMII interface, the TXC and RXC has to be sourced by the corresponding PHY or MAC right? In that case, should we define which device would act as PHY and which would act as MAC between the devices?

I want to know which is the strap option for the RGMII interface. If you see on page 12, the LED3[1,0] option, defines the GMAC interface. In my case, it is RGMII. But the next strap, LED2_1 defines whether the GMAC is in PHY mode or MAC mode. But this strap seems to be mentioned only for MII/RMII/GMII interfaces. I am confused.

 

[FvM]

The answer is simple. Unlike GMII, RGMII doesn't involve switching of pin functions because RX/TX are symmetrical. Back-to-back RGMII requires however additional delay register settings.

 

[FreshmanNewbie]

The answer is simple. Unlike GMII, RGMII doesn't involve switching of pin functions because RX/TX are symmetrical. Back-to-back RGMII requires however additional delay register settings.

Thank you for the answer. I just want to understand how you mention that back to back RGMII requires additional delay register settings? And how to find this in the datasheet? Is the delay a mandatory one for back to back RGMII?

 

[FvM]

Read 3.5.2.6