Difference between Ethernet standards - Page 1
Forum section: electronics / beginners

author: Freshman
author_rank: Regular Contributor
timestamp: August 28, 2024, 06:05:24 am
content: I have researched on the difference between 1000BASE-T and 1000BASE-TX.My research findings:1000Base-T and 1000Base-TX are both full duplex only. T uses all four pairs bidirectionally, while TX uses two pairs to transmit and two pairs to receive.100Base-TX can be full or half duplex. It uses one pair for transmission and one pair for reception.I also wanted to find what does T and TX mean?From my research, I saw that T stands for Twisted pair. However, I couldn't find what does TX imply?1. Can someone tell me what does X in TX stand for?2. I also found that there's a new standard like 1000BASE-KX. Can someone tell me what does KX imply, too? I found it is something to do with backplane products. Any insights on this will be really helpful for me.

author: Nominal Animal
author_rank: Super Contributor
timestamp: August 28, 2024, 08:15:53 am
content: The Wikipedia article onEthernet physical layersshould clear these up for you.

author: forrestc
author_rank: Unknown
timestamp: August 28, 2024, 09:08:16 am
content: Quote from: Nominal Animal on August 28, 2024, 08:15:53 amIn addition, the 802.3 standard set available for free fromhttps://ieeexplore.ieee.org/browse/standards/get-program/page/series?id=68can provide even deeper understanding.In short/summary: 1000Base-T means 1000 Mb/s baseband ethernet over twisted pair. Note that besides "T" there are also letters like "F", "S", "B", and "L" and others which are different types of fiber or other mediums, and of course there are different speeds like 100 or 10G.The remaining letters (if any) refer to how the ethernet is encoded on the medium. The Wikipedia article Nominal Animal linked to is a good quick reference, and if you want a full reference, the standards can give you specific details.All of the other letters after the medium letter (and to some extent the medium letter itself) seems like a game of Fizzbin. Just when you think you understand what a certain letter or digit means, you find an exception to that rule. As a result, I've ended up resorting to just memorizing the types in common use.That brings up the final point I want to make - whenever a new speed of ethernet is introduced, there are usually several different competing standards for how they go on the wire. Over time, some of these standards will become what everyone uses. For example, 1000BaseT is pretty much the only gigabit ethernet over twisted pair standard in use (other than perhaps 1000BaseT1 which is a new automotive ethernet standard).edit: I fixed my typo so that 1000BaseT is correctly reflected as the correct standard that is regularly in use - I accidentally said 1000BaseTX. I also removed my statement about X referring to 8b/10b encoding with is only correct at 1000BaseT (and maybe others).

author: bson
author_rank: Unknown
timestamp: August 28, 2024, 07:38:27 pm
content: Then there's the SFP (Small Form Pluggable) which conveniently maps to medium F (fiber), S (840nm), P (Passive/PON capable). It's almost like someone had to invent a TLA (3-letter acronym).

author: ejeffrey
author_rank: Super Contributor
timestamp: August 29, 2024, 02:27:43 am
content: The T and TX don't really mean anything. They are just names to differentiate two ways of transmitting Ethernet frames at 1 gigabit over twisted pair. They are intended to be a bit evocative of twisted pair but that's it. 1000Base-TX is also obsolete for years and was never widely used. 1000Base-T1 is a third twisted pair standard that uses only a single twisted pair, and is used in automotive applications.1000Base-KX is backplane Ethernet. It's intended for Ethernet communication between cards in a backplanes system. It has no relation to 1000Base-T, TX, or T1. It's basically the encoding used for the various fiber optic Ethernet standards, but using electrical signalling rather than optical.

author: ejeffrey
author_rank: Super Contributor
timestamp: August 29, 2024, 02:37:23 am
content: Quote from: forrestc on August 28, 2024, 09:08:16 amNot really. It's just a letter. The 1000Base-X fiber encodings do use 8b10b, but 1000Base-TX does not. 10 gigabit and above usually uses 64b66b for the line encoding although the older XAUI and RXAUI media independent layers use 8b10b, and some of the sub layers inside a 10 Gb PHY/MAC have a 10 bit interface that looks a lot like the 8b10b code words.

author: LoveLaika
author_rank: Frequent Contributor
timestamp: August 29, 2024, 10:45:47 pm
content: This might not be entirely accurate, but considering how an Ethernet cable (at least thinking of a Cat 5e and Cat 6 for comparison) could just be thought of as twisted wires and nothing else, it's kind of amazing how they can be rated for different speeds. It's like, they're just copper. What kind of little tweaks can one do to a simple cable to make one rated for faster speeds than the other?

author: ejeffrey
author_rank: Super Contributor
timestamp: August 30, 2024, 12:40:25 am
content: A bunch of things. Comapred to Cat 5e, Cat 6a uses thicker wires and thicker dielectric for lower losses. It has tighter twisting to reduce crosstalk. And it has separators between the pairs which reduces both crosstalk and loss.

author: forrestc
author_rank: Unknown
timestamp: August 30, 2024, 04:04:39 am
content: Quote from: ejeffrey on August 29, 2024, 02:37:23 amYep, I was wrong - I had verified my recollection against some incorrect source on the internet which matched my recollection. So, I've removed that part of my original post.But - I also knew better. Trying to determine anything about the underlying medium and/or encoding based on the set of letters beyond "1000BASE" (or whatever speed+Baseband) prefix isn't something one can really do with any accuracy.

author: LoveLaika
author_rank: Frequent Contributor
timestamp: August 30, 2024, 06:45:21 pm
content: Thanks for that. Given all that, to me, it sounds like a question of "Here's this thing. Without adding anything (very mildly), how can we make it better?"You're (very minimally) adding stuff that improves it without requiring a complete overhaul, and you're tweaking parts of it to improve performance (not to mention the improvements in manufacturing that allow for this kind of thing, maybe). It's kind of mind-blowing to think about it.Kind of makes me wonder what's next. Would you twist the cables even tighter, (maybe) use different insulation for some purpose? Looking into some deep abyss and all.

author: pcprogrammer
author_rank: Super Contributor
timestamp: August 30, 2024, 07:03:26 pm
content: Quote from: ejeffrey on August 30, 2024, 12:40:25 amAlso using actual copper instead of copper clad aluminium, extra shielding per cable or even per twisted pair. (UTP vs STP)All these factors interact with what speed can be run over a certain length of cable.

author: bson
author_rank: Unknown
timestamp: August 30, 2024, 07:13:10 pm
content: RJ-45 is a dead end, while cat 6 support 5G and cat 6A supports 10G, the RJ jack and the necessary magnetics are getting physically difficult to operate at 250 and 500MHz respectively. Meanwhile you get a 4 pack of 10G LC SFP+ transceivers for $68 on Amazon and a four pack of LC terminated 0.5m patch cables for $25, so this is already cheaper and less exotic than insisting on using RJ jacks for 10G. And it's only going to get cheaper - which means the RJ jack is going to join vampire taps and BNC T taps as a piece of history. The next step isn't 10G RJ, it's going to be something akin to integrated LC connectors/terminals. And those can run up to 40G already today, so have a path forward.

author: J-R
author_rank: Super Contributor
timestamp: August 31, 2024, 04:24:09 am
content: 2.5GBASE-T and 5GBASE-T are officially supported on Cat 5e up to 100 meters. Many modern devices are now shipping with 2.5GBASE-T. So RJ-45 is going to be around for a long time.