RJ45 Interface: Concept, Color Codes, and Cable Types Discussed

Published on Updated on March 27, 2024

RJ45 is one of the popular Ethernet interfaces where RJ stands for registered jack. A registered jack (RJ) is basically a standardized telecommunication network interface.

There are multiple types of registered jack (RJ) interfaces such as,

  • RJ11
  • RJ14
  • RJ25
  • RJ45

However, the RJ45 interface enables connection to local exchange carriers or long-distance carriers for voice and data transmission. In wired communication, the RJ45 interface is of great significance. It is most applicable in wired twisted-pair connections. There are different devices available that are compliant with the RJ45 jack interface such as RJ45 cables, switches with Rj45 connectors, etc.

However, before utilizing or integrating these devices in your Ethernet network, it is essential to understand the RJ45 interface properly. This post offers insights into the RJ45 interface, its importance in Ethernet connections, and its related devices.


An Overview of RJ45 Interface

In this interface, the number 45 shows the interface standard under standardized telecommunication network standards. RJ and 45 collectively form RJ45 which indicates a type of connector jack that is commonly used in Ethernet networks with twisted-pair connections.

The RJ45 jack connector looks similar to the telephone cable connector but it is slightly wider. It features 8 pins to connect 8 separate cables or wires. All 8 wires signify 8-position, 8-contact (8P8C) with modular plugs and jacks integration. Out of the 8 pins, 4 pins act as data transmitters and the other 4 pins act as the receivers of the data.

The RJ45 interface is integrated with the network switches for the Ethernet networks. The switches with RJ45 connectors are found suitable for almost any involving Ethernet connectivity. The RJ45 jacks and switches with RJ45 jacks are most commonly used in telecommunication, industry automation, data center connection, etc.

RJ45 Color Code

The 8 wires of the RJ45 jack are color-coded with 8 colors out of which 4 are solid colors and 4 are tripped. The wires are categorized in two different versions, one is T-568A and T-568B.

The RJ45 color codes according to T-568A and T-568B standards are listed below.

T-568A T-568BWhite/Green- Stripped (Receiver +) White/Orange- Stripped (Transmitter +) Green (Receiver -) Orange (Transmitter -) White/Orange- Stripped (Transmitter +) White/Green- Stripped (Receiver +) Blue Blue White/Blue-Stripped White/Blue- Stripped Orange (Transmitter -) Green (Receiver -) White/Brown- Stripped White/Brown- Stripped Brown Brown

RJ45 Cables Types

The RJ45 cables are utilized in various Ethernet networks. However, the switches with RJ45 connectors demand different cable capabilities. The RJ45 cables are therefore categorized in the following categories.

  • Category 5 (Cat5): The category 5 or cat5 RJ45 cables feature two twisted-pair cables that enable a maximum of 100 meters of transmission. These cables are ideally used for transmission of 100MHz frequency at the speed of 100Mbits per second. The advanced or upgraded version of cat5 cables is available called cat5e which uses 4 twisted pair cables. This version of cat5 cables is capable of transmitting data at gigabit frequencies over a short transmission distance.
  • Category 6 (Cat6): This category of RJ45 cables features improved shielding and stringent transmission standards. These cables offer 1000Mbit per second transmission at a transmission frequency of 250MHz. The upgraded version Cat6a offer 500MHz of transmission frequency.
  • Category 7 (Cat7): The Cat7 cables are designed for 600MHz transmission frequency in 10 Gigabit Ethernet networks. These cables feature hardwired construction. An upgraded version of these cables, Cat7a offers 100MHz of transmission for 40/100-gigabit transmission speeds.

Now that the RJ45 interface is discussed thoroughly, the RJ45 cables and switches with RJ45 jacks can be used effectively in the Ethernet networks. However, the quality of RJ45 jacks and cables, and switches must be assured to get efficient and reliable performance. That is why you must source this equipment from the trusted suppliers like VERSITRON. The company offers MSA-compliant communication and data transmission devices of high quality and assured performance efficiency.


RJ45 connectors are used with RJ45 cables in different locations such as campuses, homes, offices, data centers, audio and video setups, and industrial control systems. They're utilized to link various networking devices like computers, laptops, Wi-Fi routers, printers, modems, surveillance cameras, and access control systems.

The arrangement of wires in the RJ45 connector is specified by the T568A and T568B wiring standards. Although both standards utilize the same 8-pin connector, the termination of wires within the connector differs for each standard. T568A is commonly used in Europe and some other regions for Ethernet networking, while T568B is preferred in North America. It is essential to maintain consistency in wiring standards throughout the network to ensure proper connectivity and compatibility.

Yes, RJ45 connectors can be used for both Ethernet and telephone connections. However, it's important to ensure proper labeling for cables used in both connections, as the wiring configurations differ. Ethernet connections utilize all 8 pins, while telephone connections only use two or four pins.

The maximum data transmission speed supported by an RJ45 connector for older Ethernet standards ranges from 10 Mbps, while for modern Ethernet standards such as 10GBASE-T, it ranges from 10 Gbps or higher. It also depends on factors such as the connector's quality, Ethernet cable category, and networking equipment.

Rich Tull

Rich Tull
R.W. Tull is the President of Versitron, a leading technology company specializing in data communication and networking solutions. With expertise in Guiding network switches and media converters, R.W. Tull has played a pivotal role in driving Versitron's success. His deep understanding of these technologies has enabled the company to provide innovative and reliable solutions to clients. As a visionary leader, He ensures that Versitron remains at the forefront of the industry, delivering cutting-edge networking solutions that enhance data communication efficiency.
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