Ethernet Cat5 Cable (RJ-45) Pinout

Recording the pinouts for Ethernet Cat5 RJ-45 connectors, for straight thru and crossover cables. They are different than I expected. The two links (below) have colored sketches which may be easier to understand.

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Notes

Note that the pinout according to the standard is not what I expected. Note the splitting of pair 3 (568B pinout) or pair 2 (568A pinout). What I was doing works, but I've only used it in 10 MBPS networks, I had better switch to the standard for my 100 MBPS links.

To make a standard (straight thru) cable, use the 568B pinout on each end.

To make a crossover cable, use the 568A on one end and the 568B on the other end.

Because the 568B pinout is used on both ends of a straight thru connection, I show the 568B pinout first.

Looking from the top (the surface opposite the plastic latch), with the connection (open end of the connector) pointed to your right, you can read from top (pin 1) to bottom (pin 8), just the way the tables are laid out.

If you only have four conductor cable, pins 1 (Rc+), 2 (Rc-), 3 (Tx+), and 6 (Tx-) are the essential pins. The Tx+ and similar designations are misleading, clearly what is transmit on one end is receive on the other end.

568B Pinout

568B Pinout (below): For both ends of a straight thru cable or one end of a crossover cable — View with latch down

568A Pinout

568A Pinout (below): For the other end of a crossover cable — View with latch down

Resources

See Resource Recommendations. Feel free to add additional resources to these lists, but please follow the guidelines on ResourceRecommendations including Guidelines_for_Rating_Resources.

Recommended

• (rhk) EIA/TIA 568A & 568B Standard; ; —
• (rhk) the 5-in-1 network admin's cable; — "ethernet / crossover / modem / null modem / Cisco console"
• (rhk) [[][]]; ; —

Contributors

• () RandyKramer - 13 May 2003
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