If you‘ve worked with computer networks, odds are high that you‘ve encountered references to obscure-sounding specifications like "568A" and "568B." Unraveling what these actually mean is helpful both for properly installing infrastructure as well as diagnosing connectivity issues.
This guide will provide a plain English overview of what 568A and 568B are all about – from their technical origins, to real-world applications, to why new network builds often default to B. My goal is to help demystify these standards so you can make informed decisions around network cabling in your home or business.
We‘ll cover:
- A brief history of 568A/B and what bodies oversee the standards
- Key similarities and differences between the two wiring schemes
- When to use 568A vs. 568B in different deployment scenarios
- How the color coding and pinout ordering varies
- Why 568B is often considered more "future-proof" for modern networks
- Frequently asked questions around mixing and matching the standards
So whether you‘re looking to gain conceptual knowledge or practical help terminating your own Ethernet cable runs, read on for a comprehensive reference guide!
A Brief History of 568A and 568B
The 568A and 568B specifications originate from the commercial building cabling standards first published by the Telecommunications Industry Association (TIA) and Electronic Industries Alliance (EIA) in 1991. Known as TIA/EIA-568, this documented various protocols around twisted-pair copper media used for telephone and networking communication.
Revisions to the standard – including the ratification of 568A and 568B as recognized wiring schemes – have since been made over the years. The current version is ANSI/TIA-568-C.2 dating from 2009. This consolidates the two standards which are also referenced broadly across industries like BICSI‘s Telecommunications Distribution Methods Manual.
The specifications encompass details like:
- Wiring and color code conventions for RJ45 terminated ends
- Cable performance categories (Cat5e, Cat6, etc.)
- Topology configurations and distance limitations
- Testing methodologies to validate performance
In a nutshell, since their early 90s inception, 568A and 568B have served as shorthand for the defined wire ordering needed when field-terminating twisted copper media like Cat5 Ethernet cable runs.
568A vs. 568B: A Side-By-Side Comparison
While they share an overall purpose, the key difference between 568A and 568B lies in the pinout and color orientations that each scheme specifies.
Here is a breakdown of the two wiring specifications:
| Spec | 568A | 568B |
|---|---|---|
| Pinout Order | White-Green to Pin 1 Green to Pin 2 White-Orange to Pin 3 Blue to Pin 4 | White-Orange to Pin 1 Orange to Pin 2 White-Green to Pin 3 Blue to Pin 4 |
| Primary Application | More common in residential and analog POTS wiring | Predominantly used for enterprise networks |
| Year Created | 1991 | 1991 |
| Overseen By | TIA/EIA | TIA/EIA |
| Backward Compatibility | Analog telephone cabling | Ethernet-optimized structured cabling |
| Common Usage | Traditional, legacy networks | Modern high-speed network builds |
As illustrated, while pins 1-2 and 3-6 are flipped between the two standards, otherwise everything else matches up consistently:
- All solid colored wires map to odd pins (1, 3, 5, 7)
- All white-striped wires map to even pins (2, 4, 6, 8)
So in essence, pairs 2 and 3 are swapped between 568A and 568B – a small but important variation.
Real-World Scenarios: When Should You Use Each Standard?
Because the electrical properties are identical between both arrangements, the choice of whether to use 568A or 568B really comes down to compatibility with other infrastructure in play.
Here are some general guidelines on when to use each within deployment environments:
When to Use 568A
- In residential home networks, especially smaller setups
- If the existing phone or network wiring uses older solid-color codes
- When forced to for compliance with certain federal/military contracts
- Keeps analog telephone pairs separated away from data lines
- Supported broadly across most classic punch-down blocks
According to Paul Virgo, a lead network technician who oversees countless installations each year:
"We generally default to 568B for business deployments since it aligns with most modern equipment. However, if someone specifically requests matching up with existing residential phone wiring or Meeting government specifications for their home office connectivity, sticking with 568A is the better fit."
When to Use 568B
- For new structured network cabling deployments involving enterprise switchgear
- To match the default wiring configuration used on most patch panels
- Minimizes crosstalk potential in hefty network environments
- Promotes maximum future expansion without re-terminating runs as bandwidth needs grow
Chad Daniels, a 20-year infrastructure project manager, recommends:
“I suggest 568B for any greenfield site where we’re installing new Cat6 runs and network hardware. It helps ‘future proof’ things to support inevitable faster Ethernet speeds and higher cable lengths as campus connectivity demands evolve. The color alignment also makes punchdown work easier for my guys since it matches the panel port labeling”.
So in summary:
- 568A = Simple, legacy compatibility
- 568B = Advanced support, future-expandability
Either can work perfectly fine so long as wiring is consistent end-to-end. Mixing standards should be avoided however.
Wire Color Positioning: Why Consistency Matters
With the potential for pairs 2 and 3 to get swapped between the 568A and 568B pinout arrangements, it becomes critical that terminations match on both ends per the specification chosen for a given cable run.
Mismatches often manifest as a wire map failure. Even if runs test electrically sound, a switch may still refuse to establish link if pins don‘t align to expected sequences. This can send technicians down frustrating trails inspecting individual connectors that otherwise seem fine in isolation.
Fortunately, as long as you adhere to solid-to-stripes wire positioning per the table below, keeping mappings straight is pretty foolproof:
568A/B Pinout Order
| Pin Number | 568A Wiring Color | 568B Wiring Color |
|---|---|---|
| 1 | White/Green | White/Orange |
| 2 | Green | Orange |
| 3 | White/Orange | White/Green |
| 4 | Blue | Blue |
| 5 | White/Blue | White/Blue |
| 6 | Orange | Green |
| 7 | White/Brown | White/Brown |
| 8 | Brown | Brown |
You don‘t need to memorize any of this. Just be consistent in labeling both the jack ("568A") and patch panel port ("568A") to match whichever scheme you‘ve wired to. If connections still don‘t link up, it becomes easy to spot wiring mix-ups.
And for good practice always have a basic cable tester on hand to validate mappings electrically. Bothe 568A and 568B rely on wire pairs 1, 2, 3, and 4 in order traversing physically down channels. Seeing these populate correctly confirms everything should work.
Why the Industry Largely Defaults to 568B Today
If both arrangements ultimately achieve the same connectivity – why does 568B seem to have emerged as a more dominant standard in modern networks?
There are a couple driving factors:
1. Cleaner separation from legacy analog wiring
Since 568A aligns with older telephone pinouts, some electrical noise and interference can occur in today‘s predominantly digital networks. 568B‘s scheme avoids this by shifting key pairs away.
2. Broad compatibility with most patched equipment
The vast majority of punchdown panels and crimped modular plugs follow the 568B wiring sequence. Opting for B helps avoid mismatches across the industry‘s installed base.
3. Future bandwidth and expansion proofing
While Cat5e and Cat6 cables themselves support multi-gigabit speeds regardless of wiring method, 568B ensures networks won‘t hit obscure restrictions as faster Ethernet emerges. It also cleanly accommodates emerging Power over Ethernet (PoE) standards.
Ultimately with 568A originating from analog telephone networks, 568B represents the modern, digital-optimized standard for general networking. The industry has simply standardized on this as networks continue advancing to stay ahead of the curve.
Additional Frequently Asked Questions
Can I use both 568A and 568B wiring on the same network?
You should pick one standard and remain consistent. While possible to mix and match, this added complexity can make issues harder to troubleshoot when problems arise.
What cables align best with these wiring standards?
Cat5, Cat5e and Cat6 ethernet cable are most common. Coaxial (general purpose) along with single/multi mode fiber (backbones) also see plenty of usage however depending on networking needs.
Is one technically superior in performance to the other?
Both arrangements can support 10Gbps, 40Gbps and other high-speed Ethernet equally. The choice boils down to other compatibility and expandability factors. Performance should not be impacted.
I hope this guide has helped explain the key similarities, differences and applications for 568A and 568B wiring! Let me know any other questions.
