How do RJ45 connectors work?

How do RJ45 connectors work?

RJ45 is a kind of connector, principally employed for Ethernet networking, which includes connection with computer network cards, wi-fi access points, data switches, routers. It is connected to each ending of Ethernet wires and serves as the principal source for transferring data. RJ is an acronym for registered jack, and ethernet cables are also known as RJ cables.

The most popular type for RJ cables is identified as CAT5 (Category 5). In simple terms, connectors at the end of ethernet wires are known as RJ45 connectors that also designate how the cables are wired, while ethernet cables are termed as CAT5 (also RJ cables) which show the highest speed the cable can attain.

RJ connector comes with eight pins, which symbolize it can house eight wires inside. All these wires come in various colors, i.e., four are in solid color while the remaining four are stripped. These wires are combined in twisted pairs that help in decreasing the crosstalk and canceling electromagnetic interference.

These wires are not shielded and are basically twisted for noise reduction. CAT cables are frequently applied in networking and can manage bandwidth around 100mbps.


How do RJ45 connectors work?

These cables are not recommended to work in high-speed conditions; in that case, CAT5 is extensively replaced by CAT6. RJ45 cables deem feasible for both long and short distances, and apart from supporting ethernet protocol, they also work for ATM and serial ISDN T1 and E1. As explained before; RJ45 comes with eight wires, but just four of them take part in the communication where Pins numbers 1 and 2 are employed for data transmission, the remaining ones; PIN 3 and PIN 4 are utilized for receiving information. (exclusively in ethernet interface).

In serial and Integrated Services Digital Network protocols, all pins get involved in the communication and are wired in a straight-through configuration. It is essential not to get confused between RJ ports and RJ connectors. Both are the part of RJ protocol where connectors work as a (male) connector, and port that receives the connector is known as (female) port.

In RJ45 category 6, the cable consists of 6 wires that can be utilized for data transmission. Out of these six internal wires, only four are really used. The producers have included an extra two in anticipation of improvements in the technology industry. They have forecasted that the cables will be required to carry greater amounts of data in the future, but at the present moment, they are not all used yet. This is similar to the theory of redundancy. The RJ45 doesn’t use the extra wires until they really need to.



  • RJ45 connectors are principally utilized in ethernet cables for data transmission. They come in two varieties, known as T-568A and T-568B.
  • As compared to the RJ11 connector, RJ45 comes with more applications that include industrial, telecommunications, and ethernet networking.
  • An 8-pin/8-position plug or jack is commonly employed to connect computers onto Ethernet-based local area networks (LAN).


If you would like to receive a quote for any of custom cables or connectors, please do not hesitate to contact us by sending an email to [email protected] or calling in the USA this phone number (682-325-1944)

Jessica Cardona

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