Show Written by Don Schultz, trueCABLE Network Expert, BICSI INST1, INSTC, Fluke Networks CCTT Sometimes choosing between two technically different options, especially if you are a novice, is a tough decision. Which way do you go, and how do you find out? Well, you came to the right blog and video! When terminating the end(s) of Ethernet cable, you have to follow a certain color code scheme, T568A or T568B. This scheme is designed to help the installer get the conductor wires into the right order so that your cable will work properly. Get this part wrong, and you may end up with a non-working cable run. Whether it be an 8P8C RJ45 plug, keystone jack, or patch panel this holds true regardless of what kind of termination you are performing. And it does not matter if it is Cat5e, Cat6, Cat6A, or Cat8. Confusion and ControversyThere are two schemes: T568A versus T568B. From a practical standpoint, they perform and function identically in a modern data network. Just be sure you are using the same color scheme at both ends of your cable and you will stay out of trouble. I happen to prefer “B”. Why? I got lazy and did not want to memorize “A”. Fifteen years ago I might have given you a different answer, but things change. T568A and T568B are the termination standards used by Internet backbone infrastructure, Internet providers and all the way down to homeowners or businesses. The only real difference between these two pin-to-pair assignments are the green and orange pairs. These two sets are swapped in the cable. Even though these are switched, they are still both effectively direct or “straight through” connections. There is misinformation out there on this topic, fortunately most of it benign. This misinformation is not malicious, but sometimes people get used to doing something a certain way and then it becomes “gospel”. The culprit is often out of date information. There are rare instances (like US government contractual requirements) when T568A may be specifically called out for use. Unless you have a customer dictating which one to use, then T568A versus T568B comes down to personal preference. If you don’t have any specific requirements to use one over the other, then simply pick one and stick with it. You don’t need to research any further. The color code schemes are defined by the ANSI Accredited Telecommunications Industry Association (ANSI/TIA). In the absence of a stated customer requirement, the 2018 dated ANSI/TIA 568.2-D revision sets the commercial building standard for how to match twisted pair wires to a plug or socket. ANSI/TIA 570-D sets the residential standard. However, the standards have changed over time and this takes some by surprise, leading to confusion and misinformation. It also leads to lively debates! As of 2018, ANSI/TIA still recommends T568A for residential installations for plug-in backward compatibility with old technology like fax machines or a plug-in base station for wireless phone handsets. If you are not using any such devices, or have no intention of plugging ancient RJ11 plugs into RJ45 wall jacks like you would a “phone jack”, then it comes back to personal preference again. In reality, just how many people are using this old equipment any longer? I personally switched over to cell phones in 2006 and have not looked back. In the past, specifically with the old TIA/EIA 568-B-2 revision written and ratified around 2001, this recommendation was different for commercial and US government spaces. TIA recommended T568A at that time and further notated US government contracts require T568A. This was to maintain backward compatibility with older equipment like in the residential space (fax machines, etc.) As of the “D” revision, this is no longer the case and that recommendation and notation have been removed. The ANSI/TIA 568.2-D commercial standard is now mute on the subject unless you have a contractual or technical reason to go with one or the other. There is a warning in the commercial standard about making certain that both ends of the cable are terminated to the same scheme. In other words, pick one and stick with it. So now that we have sorted out what the actual recommendations are, another common misconception is that one wiring scheme will perform better than the other. Let me put this to bed immediately: they are identical in regards to performance. I decided to conduct a test to prove this out. Test conditions, components, and setup:
The results of the tests speak for themselves. It is a wash on performance. T568A test T568B test Summarized results Crossover CableSo, if there is a “straight through” kind of cable run there must be a “not” straight through type (logically speaking), correct? Well, indeed there is. It is called a “cross over” cable where one end is terminated to T568A and the other is terminated to T568B. Where would one use that kind of thing? Images credit: Industrial Ethernet Book In most network applications, the standard straight through cabling method is required. For example, a computer plugged into a wall panel uses the standard cable configured with either T568A or T568B termination. This allows the computer to communicate with other devices on the local area network. Whether talking to a network printer or mail server, the data traverses the network because all the cabling has been put together using one of the above termination standards. The same is true for the cabling in the wall and the patch panel where they all terminate. Now for other applications, we may need to connect a computer directly to another computer or a host-to-host connection. As an example, we need to copy data from one computer to another, but the two computers don’t have access to a switch for help with this process. These two computers need to use a crossover cable. Please note that the use of cross-over cables is very rare in the modern age. There are some specialized applications for them, but you will likely never see it in the wild. Summing this up, the whole T568A vs T568B thing has been a needless source of confusion and controversy for over two decades. Understanding how the standards evolved and your chances of encountering a situation where you will be forced into using one scheme or the other is not likely to happen in this day and age. Just pick one and go. With that, I say… HAPPY NETWORKING!
What are some characteristic features of RJ45 connectors?RJ45 plugs feature eight pins to which the wire strands of a cable interface electrically. Each plug has eight locations spaced about 1 mm apart into which individual wires are inserted using special cable crimping tools. The industry calls this type of connector 8P8C, shorthand for eight position, eight contact.
Which type of cabling takes advantage of the 19 pin type A connector?There are currently five standard connector types available for HDMI cables, namely: Standard HDMI (HDMI Type A):Standard HDMI Connector Types use a 19 pin configuration, carrying video and audio signals.
What are the characteristic traits of GBIC?The GBIC converts the serial electrical signals to serial optical signals and vice versa. GBIC modules are hot swappable and contain ID and system information for the switch. GBIC was superseded by the small form-factor pluggable transceiver (see SFP).
What is the maximum cable segment length for a copper twisted pair Ethernet cable?Standards for cable distance recommend that Cat5, Cat5e, Cat6 and Cat6a cables have a maximum cable segment run length of 100 meters or 328 feet. The cable distance specifications are part of the Telecommunications Industry Association (TIA) and Electronic Industries Alliance (EIA) standards.
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