I have query regarding PCB design layout of Raspberry Pi (RPI). I wanted to know how LAN9512 chip(http://www.kynix.com/Detail/226404/LAN9512-JZX.html) is connected to Ethernet RJ45.
I found one of PCB layout picture which suggests there is line on PCB which goes from LAN9512 chip to Ethernet RJ45 which I guess mark as R23.
What does R23 represent in PCB design, is it some kind of system bus or USB bus?
Same way how CPU/GPU is connected to component like D2 & D3 (RAM)?
PS: I’m not at all familiar with PCB design.