The most important thing in brief:
What does “network cable assignment” mean?
The network cable layout describes how the individual wire pairs in an Ethernet cable (e.g. CAT5, CAT6 or CAT7) are assigned to the pins of an RJ45 plug. This configuration is crucial for data to be transmitted across the network without loss and in a stable manner. This is particularly relevant in structured building cabling, in companies, data centers and in private home networks.
Whether you're a do-it-yourselfer, an IT technician or a system administrator, anyone who wants to build or test a network cable yourself must know exactly how the network cable is laid out. The article provides well-founded, practical instructions, provides important background information and shows how software such as Docusnap can help with network documentation and administration.
Basics of network cable layout
A network cable consists of four twisted wire pairs, overall therefore eight cores. These wire pairs are color-coded and read:
- Couple 1: white/blue & blue
- Couple 2: white/orange & orange
- Couple 3: white/green & green
- Couple 4: white/brown & brown
These pairs are designed using twisted pair technology, i.e. twisted together to minimize interference caused by electromagnetic influences. Two pairs (pairs 2 and 3) are sufficient for 100 Mbps Ethernet (Fast Ethernet); all four pairs are used for Gigabit Ethernet.
When assigning network cables, two internationally recognized standards are used:
- TIA/EIA-568A
- TIA/EIA-568B
Both define the pin assignment of the eight wires in a twisted pair cable for RJ45 connectors. The differences between the two variants lie in the color assignment of pins 1, 2, 3 and 6. Technically, both work the same, but consistency within a network is important.
TIA/EIA-568B (particularly common in Europe)
- Pin 1: White/orange (Send +)
- Pin 2: Orange (Send -)
- Pin 3: White/Green (Receive+)
- Pin 4: blue
- Pin 5: white/blue
- Pin 6: Green (Receive -)
- Pin 7: white/brown
- Pin 8: brown
TIA/EIA-568A (used more frequently in US authorities, for example)
- Pin 1: White/Green (Send +)
- Pin 2: green (send -)
- Pin 3: White/orange (Receive+)
- Pin 4: blue
- Pin 5: white/blue
- Pin 6: Orange (Receive -)
- Pin 7: white/brown
- Pin 8: brown
The most important differences between T568A and T568B relate to the positioning of wire pairs 2 and 3 (orange and green). In practice, this means that if both cable ends are connected to the same standard (either A or B), it is a so-called Straight-through cable.
Why is the correct allocation of network cables so important?
Incorrect occupancy leads to signal loss, network failures, or incorrect communication between network components. Especially in structured IT environments, such as in companies with many clients, servers and switches, there is a consistent cabling essential for:
- Reliable data connections
- Minimize disruptions
- Error-free network infrastructure
- Professional documentation and maintenance
An illustrative example: In a medium-sized company, the WLAN repeatedly failed. After a long period of troubleshooting, it turned out that a technician had inconsistently connected several network cables in the patch panel to T568A and T568B. Some of the data packets arrived incorrectly and switches had to be reconfigured. The problem could only be resolved through a systematic review and relocation according to uniform standards.
Difference: Straight-through vs. crossover cable
An often overlooked aspect of network cable allocation is the distinction between Straight-through and crossover cables.
Straight-through cable
- Both cable ends are identically connected (e.g. T568B ↔ T568B).
- Used to connect various devices, such as a PC ↔ Switch or Router ↔ Access Point.
- Standard in modern network infrastructure.
crossover cable
- One end is occupied according to T568A and the other according to T568B.
- Used to connect the same types of devices, such as PC ↔ PC or Switch ↔ Switch.
- Less common today, as modern devices automatically recognize whether they are sending or receiving via Auto-MDI/X.
Crossover cable configuration (A ↔ B):
- Pin 1: T568A = white/green, T568B = white/orange
- Pin 2: T568A = green, T568B = orange
- Pin 3: T568A = white/orange, T568B = white/green
- Pin 6: T568A = orange, T568B = green# This is how the correct network cable assignment is achieved
Only these four wire pairs are active with 100Base-TX. With Gigabit Ethernet (1000Base-T), all eight cores are occupied and a crossover cable is no longer relevant.
Instructions: Crimp the network cable yourself
Tools and materials required:
- network cable (e.g. CAT6)
- RJ45 plug
- crimping tool
- stripping tool
- Network tester (optional but recommended)
Step-by-step instructions for assigning network cables:
- Prepare cable:
- Strip the end of the cable approx. 2—3 cm.
- Gently pull the twisted pairs of wires apart.
- Sort cores (e.g. by T568B):
- white/orange, white/green, blue, white/blue, green, white/brown, brown
- Align veins:
- Arrange the veins side by side and shorten them to the same length.
- Insert into plug:
- Make sure that each wire is correctly positioned in the plug.
- Copper veins must be visible up to the tip.
- Pressing:
- Insert the plug into the crimping tool and press firmly.
- Test:
- Check the connection with the network tester.
Safety and legal aspects
Even though working with network cables is generally harmless (due to low voltage), there are some important tips:
- Installations in companies should be carried out by qualified personnel.
- DIN EN 50173 provides guidelines for structured cabling.
- For larger networks, it is recommended to use a complete documentation for maintenance, audits, and GDPR compliance.
Benefits of Docusnap in the context of network cable configuration
Manually documenting network cables, patch panels, and switch ports is error-prone and time-consuming. Supported here Docusnap with powerful features:
- Automated recording of network infrastructure
- visualizing of cable connections, patch panels, and switches
- Exportable network plans and reports
- Integration into ITSM processes and documentation requirements
With Docusnap, IT teams always have an overview of the physical and logical structure of their networks. This is an enormous advantage, particularly in larger environments with many patch panels, floor dividers or workstations.
Explained even more quickly: Watch our Docusnap YouTube video to learn how to efficiently implement your network documentation with Docusnap.
Best practice example from practice
An IT service provider was commissioned to modernize the network cabling of a three-story office building with a total of 90 workstations. Instead of manually updating each cable in the plan as usual, the team relied on Docusnap right from the start. The cable layout was consistently implemented in accordance with T568B and documented directly with Docusnap — including floor distributors, patch panels, can labels and switch ports.
The big advantage was already apparent during the test run: Thanks to clear documentation, all ports could be assigned quickly. Changes or reinstallations could be carried out quickly without errors. During a subsequent audit by internal IT security, no complaints were identified — a direct result of clean layout, structure and intelligent documentation.
Common mistakes and what to avoid
- Different configurations on both cable ends (e.g. T568A vs. T568B)
- Wires that are not correctly snapped into the RJ45 plug
- Cables that are too curved or crimped
- Missing or incomplete documentation
Conclusion: Implement network cable assignments securely and efficiently
The correct configuration of network cables is a fundamental requirement for stable network connections. With knowledge of T568A and T568B, a clean way of working and the right documentation, network cabling can be implemented efficiently and maintained over the long term.
This is where the software comes Docusnap In play: It helps to transparently document even complex networks and maintain an overview. An invaluable advantage, especially when moving, expanding or auditing.
Try Docusnap free for 30 days and take your network documentation to the next level.
Next steps
Start with a clean and uniform layout of your network cables, seamlessly document the infrastructure and use reliable network visualization tools. With Docusnap, you can automatically record, plan and document your entire network infrastructure — including patch panels, sockets, and switch ports. Try it now for 30 days free of charge and get started right away.
