# Talk:Ethernet over twisted pair

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## Thanks

Just my thanks to all the contributors for an excellent article. I had always wondered about the term 10BASE-T, which is clearly explained here. Todd (talk) 13:45, 22 May 2010 (UTC)

## Performance Capabilities

I just achieved a stable 100Mbps data rate link using Category 5e UTP at a distance of 450 feet. Full throughput tests were not done, but I was able to perform internet speed tests averaging 5Mbps with no errors, dropped packets or frames. The fact that it was not necessary to drop the link speed to 10Mbps at that distance is noteworthy. An addition to the article page should be made to indicate that greater distances are possible with some equipment. —Preceding unsigned comment added by 205.168.82.134 (talk) 21:01, 16 September 2010 (UTC)

## Measuring throughput

Is the 10 Mbit/s measured in base2 or base10? That is, is it 10,000,000 bits/sec or is it 10,485,760 bits/sec?

It is most definitely base ten. All network communication is based on powers of ten. So, it's exactly 10,000,000 bits/sec.
Usually stated in millions (not 2^20) and almost always in bits per second. 10 or 10.5 doesn't really mean much, anyway, when you're talking about Mbps. Sln3412 06:16, 29 June 2007 (UTC)

## Hardware

I suggest include a picture of the 10Base-T plug (wall plug) What year did 10BASE-T become the norm. We read 100BASE-T came in 1995.

Almost everything new is gigabit now. But think about it; a cable/dsl connection is not even 10 M, so if you're sharing a connection, a 10 hub is fine. Unless you're tranfering huge files on your home network a lot. New computers seem to be most often gigabit, and most stuff is now 100/1000 anyway. So, I'd say 100 or 1000 is now 'the norm'. No ref I can think of to add. Sln3412 06:16, 29 June 2007 (UTC)

## RJ 45

As RJ 45 is not the correct name for the computer networking connector, or for that matter wiring diagram for the connector, all references to RJ 45 should be reviewed. —The preceding unsigned comment was added by 198.208.251.22 (talk) 18:36, 11 January 2007 (UTC).

Let me know what you think of the changes I made then. Yes, the connector is not RJ-45; the standard for the wiring is (at least under this topic) Sln3412 06:16, 29 June 2007 (UTC)

I believe the 10baseT spec came out in 1989. That, incidentally, predates the Cat3 spec.--98.218.167.210 (talk) 06:56, 15 February 2009 (UTC)

## RJ 45 WTF?

If you don't call it RJ-45, what is it, then? All of my sources call it RJ-45, all of the techs call it that. Could you point to a source that calls it something else? My sources say the connector was designed by Ma Bell and that's the designation it was stuck with -- your phone cord connector is RJ-11. —Preceding unsigned comment added by 72.17.207.50 (talkcontribs)

It is an 8P8C FCC style modular connector. Read the 8P8C article for information on what RJ-45 actually is according to the standards. Plugwash 02:45, 1 March 2007 (UTC)
Yes. We call it RJ-45 when we're talking about networks, using EOTP , but the actual plug is 8 positions with 8 conductors. Some people call it Cat 5 or a patch cable, etc. Sln3412 06:16, 29 June 2007 (UTC)

## proposed rearrangement

this article contains a fair bit of info that is applicable to all the twisted pair versions of ethernet, therefore i propose moving this to twisted pair ethernet, changing the redirects for all the variants of twisted pair ethernet to point here and then adding info here so it covers them all. Any objections? Plugwash 02:48, 14 February 2007 (UTC)

## 1000BASE-CX and 10GBASE-CX4 are off-topic

neither of these protocols have anything to do with twisted pair.

Afaict 1000BASE-CX uses twisted pair while 10GBASE-CX4 uses twin-axial which according to our article is coax with the center core replaced by twisted pair. So in both cases the signals are travelling along twisted pairs albiet higher grade ones than those used for the more common variants of ethernet. Plugwash 13:01, 8 May 2007 (UTC)
Also think about the fact that we can compare and/or contrast to make a point about the actual subject. Mentioning some of the fiber standards etc to make a point about how copper differs. etc Sln3412 06:16, 29 June 2007 (UTC)

## ...but 10GBASE-T isn't

or is it? —Preceding unsigned comment added by 90.227.241.69 (talk) 23:32, 22 July 2008 (UTC)

## 8p8c is RJ-45

Also, CompTia uses RJ-45 on its tests. Just makes sense to refer to it as RJ-45, since that is the Network+ standard. —The preceding unsigned comment was added by 72.49.124.35 (talk) 16:59, 8 May 2007 (UTC).

They call it that because it's in the context of how the plug is used/called in networking. Sln3412 06:16, 29 June 2007 (UTC)

rj-45 is att itt designation used for telephones. Only att partners can make those - like the difference between Tylenol and acetaminophen — Preceding unsigned comment added by 74.215.32.31 (talk) 17:35, 9 April 2014 (UTC)

## Cabling section

claims that Gig ethernet (1000BT) "requires a minimum" of Cat-5 - but IIRC, cat5e is typically the minimum used in this case. comments?--Boscobiscotti 18:55, 8 May 2007 (UTC)

iirc cat5 is the official minimum but in practice 5e is strongly reccomended. Plugwash 19:01, 9 May 2007 (UTC)
As I tried to say in the rewrite, what is in the standard and what works or doesn't can be two different things. Sln3412 06:16, 29 June 2007 (UTC)

## Changes

I am rather short on refs in what I changed, but I've redone quite a bit to make it a little more exact.

RE 8P8C and RJ-45: T1 and ISDN use the 8P8C also. It's called an RJ-48 in that case. The 'RJ' refers to how it's wired. Let the links to the appropriate articles explain it.

'RJ' does refer to how something is wired, but the wiring to which RJ45 refers is not Ethernet. It's a rare modem wiring. There is no RJ standard for Ethernet (because it didn't originate with telephone companies). Bryan Henderson 02:42, 23 July 2007 (UTC)

RE Cat 5: Gbps works fine on it, usually.

RE Collision domains: Too much detail to explain here that the bits are .1 nanosecond at 10 megabits, nor to explain (nor why it is) that theoretically it takes electrons about 3 nanoseconds to go 100 meters, but is probably more like 10 to 15 ns through a physical medium. Links should explain all that also, not here in here; this is about Ethernet on twisted pair copper wires. It's like discussing the supposed propagation delay from Los Angeles to Manhattan (2800 miles, something like 1.5 ms) or why you can't compare ice cores to the atmosphere. Not important, doesn't fit the context. Sln3412 06:16, 29 June 2007 (UTC)

## Flat cable modular plug vs. round cable modular plug

How does one visually tell the difference between a flat cable modular plug and a round cable modular plug? Sarsaparilla (talk) 01:04, 8 February 2008 (UTC)

Afaict it's just a case of whether there is enough space to get round cable into the back of the connector. What is more important afaict is making sure you get plugs designed for the right core type. Plugs designed for solid core will not be reliable on stranded core and vice-versa. —Preceding unsigned comment added by Plugwash (talkcontribs) 09:26, 8 February 2008 (UTC)

## Article quality

What kind of an article starts with "There are a few standards for Ethernet over twisted pair(...)"? --87.196.45.96 (talk) 05:52, 9 July 2008 (UTC)

## Removed Redirection Notice

I have removed the label at the top that states "RJ45" redirects here. For the generic 8P8C modular connector, see 8P8C. For the Registered Jack (RJ) wiring standard, see Registered jack.

Reason: The RJ45 article does not redirect here. CraigMatthews 01:12, 12 Dec 2009 (UTC)

## According to the standards, they all operate over distances of up to 100 meters.

Reference to "standards" missing. —Preceding unsigned comment added by 80.77.67.93 (talk) 12:57, 25 January 2010 (UTC)

## handling of unused pins

802.3 doesn't seem to say what should be done with the unused pins on the connector at all for 10BASE-T and for 100BASE-T it only seems to specify that they should meet certain requirements for isolation from frame ground not what if anything their connection to each other should be.

The implementations i've looked at schematics for do indeed seem to short the unused pairs. Then there is a resistor and capacitor circuit between the pairs and frame ground. Plugwash (talk) 08:03, 17 August 2011 (UTC)

Yes, that's all true. You will also find implementations that terminate each unused conductor separately and implementations where unused conductors are left disconnected. I recently changed the article from shorted to terminated. If you're generous, you might consider a short to be a form of termination (you could not consider termination to be a type of short circuit). If you're not generous, you might want to edit the article to call out all the possibilities. I would suggest the PoE standards would be a good source for references for such edits as these had to be designed to handle all termination possibilities and I believe there's some helpful discussion there. --Kvng (talk) 17:23, 17 August 2011 (UTC)

## Single pair

So about the unused pins and SPE(single pair ethernet).

```   There is a need to include wiring specs!
If possible  working equipament
```

Then how about the half duplex situation? The controller can use one pair and auto-MDI? — Preceding unsigned comment added by 177.132.101.115 (talk) 13:28, 20 January 2018 (UTC)

SPE doesn't use 8P8C and has no specified connector, so there are no unused pins. Additionally, it uses full-duplex exclusively as stated. MDI vs MDI-X and Auto MDI-X doesn't make sense with a single pair. --Zac67 (talk) 17:13, 20 January 2018 (UTC)

## Cat 5 vs Cat5e

Both of the links to Cat 5 / Cat 5e in the sentence At least Category 5 cable, with Category 5e strongly recommended copper cabling with four twisted pairs. Each pair is used in both directions simultaneously. point to the same article. That page doesn't explain the differences. See the talk page of that article, which does point out that it needs to be fixed there. — Preceding unsigned comment added by 68.183.134.245 (talk) 15:47, 2 November 2011 (UTC)

There's only one link now and Category_5_cable#Category_5_vs._5e explains the difference. ~KvnG 19:39, 7 August 2013 (UTC)

## MDI and MDI-X Statement

"Hub and switch ports with such internal crossovers are usually labelled as such, with "uplink" or "X". For example, 3Com usually labels their ports 1X, 2X, and so on". I believe this statement invites some confusion among the readers because it's probably wrong, as far as i know, uplink ports are not crossover MDI-X ports, they're just uplink ports as on normal end hosts. On a typical switch all the ports are MDI-X (or auto MDI-X) which are called Regular ports, which have internal crossover, thus straight through cable can be used between them and end hosts (with uplink port). Switches have generally few (one or two) uplink ports, to connected to core or distribution switches via a straight through cable, because uplink to regular means straight through. Please pay attention to this and if I'm right about the confusion implied by that statement, please correct it to reflect accurate information. Pritishp333 (talk) 17:07, 6 February 2015 (UTC) (sorry, forgot to sign my post, signing late)

Thanks for pointing this out. It wasn't only ambiguous, there were factual errors as well. I've tried to make the matter more comprehensible. Actually, "MDI-X" means there is an internal crossover – standard for hub/switch ports – while "MDI" isn't crossed. The rule is that there must always be an odd number of crosses, so connecting MDI to MDI (no cross) requires a crossover cable, the same as MDI-X to MDI-X (two crosses), while MDI to MDI-X and vice versa is fine with a straight cable. Zac67 (talk) 12:11, 1 February 2015 (UTC)

## Fancy table formatting

WP:ACCESSIBILITY issues and problems rendering on different platforms (mobile browser, Wikipedia app, different sized screens...) come up for me when I see editors put a lot of manual formatting configurations to make a table look good. There's a lot of that going on with the table in the Variants section. I'd like to understand what problems the editors who worked on formatting of this table were trying to solve by using, for instance, different font sizes, abbreviations and forced line breaks. I've done a quick test removing some of that and nothing seems to fall apart. ~Kvng (talk) 14:52, 7 May 2019 (UTC)

Comparison of twisted pair based Ethernet Physical transport layers (TP-PHYs)
Name Standard Status Speed (Mbit/s)[A] Pairs required Lanes per direction Bits per hertz[B] Line code Symbol rate per lane (MBd) BW[C] (MHz) Max distance (m) Cable required[D] Cable rating (MHz) Usage

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