Auto MDI-X is an Ethernet interface feature that automatically changes transmit and receive pin assignments to match the connected device. It lets modern equipment communicate without choosing a straight-through or crossover cable manually. section 3.3.2
Remember these exam and troubleshooting points:
- A crossover cable connects devices that transmit on the same pin pair by linking transmit pins on one side to receive pins on the other. section 3.3.2
- A router-to-router connection that would normally require crossover cabling can work over a straight-through cable when Auto MDI-X reverses one router’s assignments. section 3.3.2
- Know straight-through and crossover cable behavior for exams, even though Auto MDI-X usually removes the practical need to select between them. section 3.3.2
Figure 3.6 Two routers connected via a straight-through cable. The router on the right uses Auto MDI-X to adjust which pins it uses to transmit and receive data.
Visualizes two routers using a straight-through cable while one router adjusts its transmit and receive pin pairs. section 3.3.2
