What does RJ45 connector mean?

I. Definition and Use

• Full Name : Registered Jack 45, abbreviated as RJ45.
• Core Function : Transmits Ethernet data (such as internet signals), supports wired network connections, and is one of the most commonly used physical interfaces in Local Area Networks (LANs).
• Application Scenarios : Home broadband, enterprise network cabling, server rooms, router/switch interfaces, etc.

II. Appearance and Structure

• Similar to a 'crystal head' with a plastic shell, containing 8 internal metal contacts (pins). Its appearance is similar to the RJ11 connector used for telephone lines, but it is larger (RJ11 is 4 or 6 pins).
• The plug (male) and jack (female) are used in pairs. The jack is often integrated into network devices (such as computer network ports) or network cable modules.

• The 8 pins are arranged in a specific order, following  T568A  or  T568B  wiring standards (the two wire orders are different, but functionally equivalent). Common wire orders are as follows:
  • T568B Standard (More common): White-orange, orange, white-green, blue, white-blue, green, white-brown, brown.
  • The pin numbers are 1-8 from left to right, where 1/2 are used for transmitting data, 3/6 for receiving data, and other pins are reserved or grounded.

III. Differences from RJ11

IV. Transmission Rate and Classification

V. Key Characteristics

Gold-Plated Contacts ： Metal contacts are often gold-plated (as mentioned earlier, goldflash plating), improving conductivity, corrosion resistance, and wear resistance to ensure signal stability.

Shielded and Unshielded ：

Unshielded (UTP) : Commonly used in ordinary scenarios, low cost;

Shielded (STP) : With a metal shielding layer, strong anti-electromagnetic interference capability, suitable for industrial environments or strong interference scenarios.

VI. Practical Application Examples

Home Network : Computers connect to routers via RJ45 network cables to obtain internet signals.

Enterprise Cabling : Network cables in offices connect to switches via RJ45 modules to build a LAN.

Monitoring System ： Network cameras connect to monitoring hosts or switches via RJ45 interfaces.

Summary