The Issue
When making an CAT5/CAT6/CAT7/CAT8/network patch/Ethernet cable, what is the correct order of the wires and the pins?
The Answer
This guide assume we have some basic knowledge on what is RJ-45 Crimping tool, RJ45 Crimpable Connectors, Ethernet Cable, CAT5 / CAT6 / CAT7 / CAT8 (CAT stands for Category) etc.
The main problem here we want to find answer for is the order of the wires
1 Straight through cable vs Crossover cable
Straight through Ethernet Cables: Usually used for most cases, also called patch cables. Usually used for Computer to switch/modem/hub or Router to switch etc.
Crossover cable: Not used as commonly as straight through cables. It’s used for directly connecting the computer to computer or router to router without a switch in between.
Rollover cable: Usually used for connecting to a device’s console port to make programming changes to the device. This cable is not designed for carrying data, instead it is used to create an interface with the device.
2 RJ45 Connector
3 Order of the wires / pins (Straight through / Crossover / Rollover wiring)
Q: First or all, does the order of the wires matter when making the patch cable? What if we just want to make one quickly for ourselves for temporary usage?
A: Yes and no, if the order on both end of RJ45 connectors are different, we won’t be able to use it. But if we don’t follow the convention (T568A or T568B) of the orders and we make the order exactly the same on both ends, the cable will still work. After all, we should stick to the convention when we can, it is not suggested to have wrong order, but yes, it will work as a straight through cable if the order on both ends are exactly the same.
Straight through Ethernet Cables
Crossover cable
Straight through vs Crossover cable wiring, T-568A, T-568B
Note: As mentioned before, as long as the order on both ends are exactly the same, it will work as a straight through cable, but it is recommended to follow the convention, either T568A or T568B.
Rollover cable wiring
4 T568A vs T568B Which one to use?
Put it simple:
T568A is designed for backward compatibility with older telephone wires
T568B is designed for better signal isolation and noise protection for newer networking systems and products.
5 What is 8P8C?
8 position 8 contact connector
References
[1] “Ethernet Cable Wiring”, https://www.eeweb.com/ethernet-cable-wiring. [Online]. Available: https://www.eeweb.com/ethernet-cable-wiring
[2] “Network Cable”, http://diagramsentence.seewhatimean.it/lan-netwo/lan-network-cable-wiring-diagram. [Online]. Available: http://diagramsentence.seewhatimean.it/lan-netwo/lan-network-cable-wiring-diagram
[3] “RJ45 Pinout”, Showmecables.com, 2017. [Online]. Available: https://www.showmecables.com/blog/post/rj45-pinout