International and National Standards
- Ethernet wiring standards are globally recognized and defined by international and national organizations.
- The ISO/IEC 11801 standard is an international cabling standard that defines different classes of networking standards.
- In the US, the Telecommunications Industry Association (TIA) manages the ANSI/TIA-568 standard for commercial building cabling installations.
- The ANSI/TIA-568 standard specifies wire color assignments for Ethernet cables using RJ45 connectors.
T568A and T568B Wiring Schemes
- The T568A and T568B are the two primary color-coding schemes for Ethernet cables.
- Both schemes use the same RJ45 connector but differ in the arrangement of wire colors on specific pins.
- T568B is the most commonly used standard in the US and many other regions.
- Organizations typically choose one standard and maintain consistency throughout their installations.
- Mixing T568A and T568B on opposite ends of a cable is not recommended, especially for gigabit networks, as it can cause connectivity issues.
Color Code Comparison
- Both T568A and T568B share identical color assignments for some pins, simplifying memorization.
- Common colors for both schemes:
- Pin 4:
Blue
- Pin 5:
White/Blue
- Pin 7:
White/Brown
- Pin 8:
Brown
- Differences between T568A and T568B:
- T568A:
- Pin 1:
White/Green
- Pin 2:
Green
- Pin 3:
White/Orange
- Pin 6:
Orange
- T568B:
- Pin 1:
White/Orange
- Pin 2:
Orange
- Pin 3:
White/Green
- Pin 6:
Green
- To identify the wiring scheme, examine the colors on pins 1, 2, 3, and 6.
Practical Applications and Best Practices
- Understanding these standards is essential for cable installation, troubleshooting, and certification exams like the A+.
- When crimping cables, verify the color order before securing the connector to avoid errors.
- Some keystone jacks and wall plates provide color-coded guides for both T568A and T568B, simplifying installation.
- Example of a keystone jack layout:
- T568A: Green, White/Green, Blue, White/Blue on one side; Orange, White/Orange, White/Brown, Brown on the other.
- T568B: Orange, White/Orange, Blue, White/Blue on one side; Green, White/Green, White/Brown, Brown on the other.