A: Ethernet Cabling Pinouts
Which of these uses a straight-through cable: a cable between two switches? Two routers? Two PCs? A switch and a router? A switch and a hub? The list goes on for a bit. This latest question about Ethernet cabling pinouts makes you remember the combinations and apply them. Check the question, and come back here to check your answers. Post with any related clarifications or comments.
Ethernet uses crossover cables between two devices that transmit on the same pin numbers. The crossover cable crosses the wires inside the cable, so that the wires used by one device to transmit data connect to the neighboring device’s pins used to receive data. In 10 and 100 Mbps Ethernet, that means that the pair connected to pins 1 and 2 connect to pins 3 and 6 on the other end of the cable, and vice-versa.
To find cases where the devices on both ends of the link uses the same pins to transmit, you need to remember the pins used by each device. For instance, Ethernet NICs in end user devices transmit on pins 1,2, and switches transmit on pins 3,6 normally. The following list notes the two groups: devices that transmit on 1,2 and the devices that transmit on 3,6:
- 1,2: PCs, servers, most end-user devices, routers, wireless APs
- 3,6: switches, hubs
As a result, for this question, the links that should use crossover cables are links 5 and 9, making answers C and E correct.