Talk:Ethernet physical layer

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[edit] Ethernet over twisted-pair cable

Isn't this drawing incorrectly labelled TIA-B when its TIA-A? What does 'z' mean in the table? —Preceding unsigned comment added by 204.244.209.138 (talk) 11:45, 24 May 2008 (UTC)


[edit] Does this page just duplicate other pages?

There's already a gigabit Ethernet page giving details of gigabit Ethernet physical layers, and the Fast Ethernet page should probably swallow the pages for the individual 100Mbit/second standards; this page doesn't even mention 10 gigabit Ethernet. Guy Harris 17:19, 14 June 2006 (UTC)

Probably it is, though User:Oakad clearly did a nice job with it. It would probably be better to merge the respective wording and tables onto the Fast Ethernet and gigabit Ethernet and the not-yet existant early/ancient/original/10mbs ethernet pages. -- KelleyCook 18:58, 14 June 2006 (UTC)
I've merged stuff from here into Fast Ethernet, and turned the "Fast Ethernet" section of this page into a summary that points to the Fast Ethernet page. I'll look at doing the same with the Gigabit Ethernet stuff.
The Varieties of Ethernet page also has a summary of various Ethernet physical layers; should the two pages be merged? Guy Harris 21:06, 15 June 2006 (UTC)
Yes. I've done that merge. Guy Harris 08:08, 3 October 2006 (UTC)

Does this overlap with Ethernet over twisted pair. --Boscobiscotti 04:57, 8 May 2007 (UTC) I also added a link to [[autonegotiation]--Boscobiscotti 05:00, 8 May 2007 (UTC)

[edit] Echo cancelation

This sentence: "Telephones also use echo cancellation to simultaneously transmit in both direction over a single cable pair" is probably wrong. Analog telephone does not use echo cancelation. This would require sophisticated signal processing equipment which was not available in the age of analog telephony. Telephone does use echo cancelation if transmitted over a digitial medium such as ATM or IP with higher delay as pure analog switching, because the echo would be disturbing. The need for echo cancelation was one of the main critic points in ATM: 53 byte cells are too long to use without echo cancelation and thus made this expensive equipment nescesarry when ATM was introduced in the phone network, while still beeing way too short for sensible data transfers. citation: "Interconnections: Bridges, Routers, Switches, and Internetworking Protocols" by Radia Perlman. 85.178.193.38 17:29, 30 November 2006 (UTC)

The sentence is correct, actually. See the article on echo cancellation, with particular attention to its use in modems. (I've also added the appropriate links to the article.) Peppergrower 18:45, 13 November 2007 (UTC)

[edit] Minimum cable lengths

The section on minimum cable lengths is a mess. It has random links strewn throughout and a number of gramatical errors. I'm hesitant to change anything though, because I know very little on the subject. Perhaps someone else more knowledgable should have a look? Yanroy 21:13, 25 April 2007 (UTC)

As far as I can tell it is mostly wrong. There is no minimum cable length for xxxBase-T. The 802.3 spec clearly says so for 10Base-T, and for the others I see no reference to minimum length. I can't see any way that collision detection depends on a minimum cable length. As for 100Bse-FX, again IEEE says nothing about minimum length. Cisco mentions one, but doesn't give a reason. It can't be signal level; the attentuation on 2.5 meters of fiber is too small for that theory. So the only part that appears correct is the one about long haul transceivers used with short fiber (because the transmitter output power is higher than the max permitted receiver input power). Paul Koning (talk) 18:55, 25 February 2008 (UTC)

[edit] Informal tone

The minimum cable length section has stuff like "This is normally 10-100 Mb stuff" and "So here's where it gets interesting". Doesn't sound like something I'd read in an encyclopedia.

Tagging for informal tone. 59.154.26.124 23:25, 1 May 2007 (UTC)

[edit] 10x steps between revisions

I think this article would be the right place to answer an old question of mine: what motivates the exponential speed increase of 10x between each revision? Why can't we have 25 Mbps or 450 Mbps Ethernet? Exxos77 18:27, 2 May 2007 (UTC)

Economics and a pleasing sense of symmetry, I guess. For installed base, there's not much point in junking all your installed equipment for a 2.5x speedup. Generally speaking, the IEEE Task Forces have been given the job of creating the next Ethernet standard at 10x the speed but only 3x the cost. Having said that, IEEE are currently working on a 40Gbps Ethernet standard, so there goes the progression. It's not really encyclopaedic data, though, I think. Gareth8118 (talk) 13:00, 6 March 2008 (UTC)

[edit] IPoAC

IP_over_Avian_Carriers

Where does it fit? Humorous as it is, it is an actual data transfer protocol.--Marhawkman (talk) 22:56, 15 December 2007 (UTC)

It's a physical layer and data link layer protocol (not part of the Ethernet physical layer; the physical layer involves, as per the RFC, birds and sheets of paper). Guy Harris (talk) 23:19, 15 December 2007 (UTC)

[edit] Fair use rationale for Image:Ethernet73.gif

Image:Ethernet73.gif is being used on this article. I notice the image page specifies that the image is being used under fair use but there is no explanation or rationale as to why its use in this Wikipedia article constitutes fair use. In addition to the boilerplate fair use template, you must also write out on the image description page a specific explanation or rationale for why using this image in each article is consistent with fair use.

Please go to the image description page and edit it to include a fair use rationale. Using one of the templates at Wikipedia:Fair use rationale guideline is an easy way to insure that your image is in compliance with Wikipedia policy, but remember that you must complete the template. Do not simply insert a blank template on an image page.

If there is other fair use media, consider checking that you have specified the fair use rationale on the other images used on this page. Note that any fair use images lacking such an explanation can be deleted one week after being tagged, as described on criteria for speedy deletion. If you have any questions please ask them at the Media copyright questions page. Thank you.

BetacommandBot (talk) 19:42, 13 February 2008 (UTC)

[edit] Advertisements in Links

Links are filled with advertisements (Collection of product information from various vendors, related to ETH PHY only in business sense) and useless information (some guys are hugging and their bios...? I understand it's after a short description of a transciever product, but then again it's a product of a company). I am going to remove them. —Preceding unsigned comment added by Slidersv (talk • contribs) 02:27, 7 April 2008 (UTC)