? I'm lost...
On 10/100 ethernet you need dedicated transmit (TX) and receive (RX) pins, so that TX would always go to RX. For that reason devices which were to connect to network would have MDI (medium dependent interface) while network device like hubs, switches would have reversed TX/RX layout or MDI-X. If you wanted to connect two PCs directly (MDI to MDI), you would need crossover cable.
On gigabit ethernet and above, there are no dedicated TX/RX pins, all data can be transmitted and received simultaneously (auto MDI-X).
If you have gigabit ports on switch or router, even when if you plug in a 10/100 device like Access, gigabit ports would automatically adjust, no matter what cable is used (straight or crossover).
Sometimes though, it won't work as intended and you have to be mindful of which cable is used (very rare these days).