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I merged in 100BASE-TX, 100BASE-T, 100BASE-SX, and 100BASE-FX into this collective article. It still needs a lot of work. KelleyCook 18:44, 14 June 2006 (UTC)
utp cat5 consists of 4 twisted pairs instead of 2 —The preceding unsigned comment was added by 81.241.228.203 ( talk • contribs) 05:19, 29 June 2006 (UTC).
Note that today I modified the 100base-FX section to include support for both multimode and single-mode fiber. 100base-FX is called 100base-FX despite what physical media it travels over. You can have 100base-FX over mm OR 100base-FX over single-mode. The only real difference (besides the media itself) is that maximum (and sometimes minimum, research saturation etc) distance you can run. The spec specifically calls out 2km as the maximum distance of multimode for 100base-fx (also 10base-fl), but in the case of single-mode, the distance is entirely based on your optical fiber budget calculated by subtracting rx sensitivity from tx power. Normal SM optical transceivers support at least 10km, and can range up to 110km. Note that you always have to run full duplex over the 412m 100mbps limitation no matter what type of media you employ.
Support for my contention that 100base-fx supports both mm and sm can be verified by looking at Spurgeon's "Ethernet: the definitive guide" page 149. (besides the fact that I have 12+ yrs industry experience, and there are thousands of products on the market that support both mm and sm under the 100base-FX protocol) Kmwiki ( talk) 21:17, 15 January 2008 (UTC)
I've put in the connectors list from 802.3 but it appears there may be other connectors in use, does anyone have any sources for what if any unofficial connectors are common? Plugwash 01:47, 22 March 2007 (UTC)
Plugwash --- I'm not sure about sources, I could probably scrounge some up if necessary.
In the industry, the most common connectors for 100base-FX are either ST or SC, with SC being the most popular. MT-RJ connectors are also used when you are looking for high-density. So, when you need, say (24) 100base-FX ports in a 1U switch, it's almost imperative that a smaller form factor connector be used. With the popularity of gigabit fiber, some 100base-FX devices are even being shipped with LC connectors, the common choice for SFP-based gig fiber solutions. Kmwiki ( talk) 21:05, 15 January 2008 (UTC)
One other thing --- although I didn't remove this, MIC connectors on ethernet devices are pretty rare. Unless you get into some goofy industrial proprietary market, you are unlikely to find a MIC connector on a true ethernet device. Check Nortel, 3Com, Cisco, and you won't find a single vendor putting a MIC connector on an ethernet device. Kmwiki ( talk) 21:23, 15 January 2008 (UTC)
Hi. Is there any good reason why the wiring diagram shows the legacy (non-preferred according to the TIA/EIA-568-B standard) T568B wiring configuration, instead of the recommended T568A configuration? --- Joe. —Preceding unsigned comment added by 61.8.13.206 ( talk) 00:26, 23 January 2008 (UTC)
It is very easy to understand the transmit speed 100Mbps comes from 4 bits at a time, 25 Mhz per second. But, can somebody please tell me, how does a single twisted pair wire transmit four bits at a time (for one direction)? —The preceding unsigned comment was added by 221.169.12.48 ( talk) 16:11, 9 April 2007 (UTC).
Hi, I have been looking for books talking about ethernet physical layer. Now I know the parallel signals in 4 bit wide 25MHz go through a 4B5B encoding before they are serialized and transmmited to PMA sublayer. There is still one thing that confuses me. In the page of wiki talking about CAT 5 cable, it says: "Currently unrecognized by TIA/EIA. Provided performance of up to 100 MHz...". But the PMA sublayer is clocked at 125MHz, how does a CAT 5 cable designed to carry "up to" 100 MHz actually carrying 125Mhz signal in 100BASE-TX ethernet? Is there anything wrong with the page of wiki? Or the signal is actually not transmitted at 125Mhz over the wire? Or is there anything wrong with my understanding?
My understanding is that it actually is transmitted at 125 symbols/s, but the MLT-3 encoding of those symbols makes the worst-case "fundamental frequency" only 31.25 MHz. And that MLT encoding ... somehow ... avoids the bandwidth limitation of CAT 5 cable. If you ever find a good explaination, please put it in the article, OK? -- 75.37.227.177 21:52, 31 July 2007 (UTC)
What does the TX in 100base-TX stand for? —Preceding unsigned comment added by Panarchy ( talk • contribs) 03:58, 26 February 2008 (UTC)
T = twisted pair - not sure what if anything the x stands for here but it does distinguish it from 100Base-T4 Qureus1 ( talk) 07:03, 7 February 2009 (UTC)
in http://en.wikipedia.org/?title=Fast_Ethernet&diff=next&oldid=111062033 soccerman58 claims that there is no such thing as half duplex 100BASE-FX as there is no "need for it". This seems to be contradicted by the relavent section in 802.3 (confusingly they have a general X section which applies to both TX and FX) which explicitly talks about half duplex and is nonsensical (TX and FX both have seperate transmit and receive pairs but both need to be able to run in half duplex mode to support hubs). Plugwash 01:23, 22 March 2007 (UTC)
Just as confirmation, there is most certainly 100base-FX half duplex. You can end up with a duplex mismatch between two ethernet switches, for instance, where one is set to full and the other to half. The Full side would intermittently step on the half side, causing serious performance problems on the link. It's a common task for admins to check the duplex setting on the ethernet switches involved to ensure they are both set to full. Kmwiki ( talk) 20:58, 15 January 2008 (UTC)
My text, Network+ Guide to Networks, explains that in half-duplex mode one strand is used for transmission only and the other for reception only while full-duplex mode uses both the fibers to send and receive data. This text claims that the segment length is limited to 412 meters in half-duplex mode while if used in full-duplex mode the same cable can be 2000 meters. If true, why would the mode affect the segment length like this?
Qureus1 (
talk)
07:02, 7 February 2009 (UTC)
What are the maximum physical and logical sizes of 100Base-TX LANs?
If one segment can be 100m, then two endpoints can be 200m apart, via one switch. But switches can be chained/cascaded, so the maximum distance could be increased. What is the limit?
(Note also the difference between theory and reality. Some equipment works better over real cable segments, some worse. So the 100m segment limit is fuzzy. Some equipment may auto-negotiate down to lower speeds when there are cable problems, but still function somewhat.)- 96.237.78.13 ( talk) 02:46, 25 August 2010 (UTC)
As part of the same edit mentioned about a mention of single mode fiber was added to the FX standard, later a bracketed 100BASE-LX was added after this. Is this an unoffical standard? an unofficial name for using a fiber type that is out of spec but works? something else? Plugwash 01:47, 22 March 2007 (UTC)
Plugwash, if its any consolation, I've never heard of 100base-LX, now 1000base-LX is a different story.
The common ethernet standards are currently (beginning 2008):
(10mbps finally being phased out at the chip level due to ROHS european elimination of lead-based stuff)
10base-5, aka 10mbps Thicknet
10base-2, aka 10mbps Thinnet
10base-T, aka 10mbps Twisted-pair
100base-TX, aka 100mbps twisted-pair
100base-FX, aka 100mbps over fiber
100base-SX, UNPOPULAR 100mbps over mm fiber only standard, 300m maximum, cheaper 850nm optics.
1000base-SX aka gigabit over mm
1000base-LX/LH aka gigabit over SM (usually, unless you use a mode-conditioning patch cable on both sides and run it over mm)
1000base-ZX aka gigabit over sm super long haul.
Don't ask me about 10gig yet. :)
Kmwiki ( talk) 21:34, 15 January 2008 (UTC)
100BASE-LX10 is described here now, along with 100BASE-BX10; yes, that's what IEEE 802.3-2012 calls it, even though both can, apparently, run over distances > 10 km - the spec says "The 100BASE-LX10 and 100BASE-BX10 PMD sublayers provide point-to-point 100 Mb/s Ethernet links over a pair of single-mode fibers or an individual single-mode fiber, respectively, up to at least 10 km." (emphasis mine), and some Googling finds references to 100BASE-{B,L}X20 and so on. Guy Harris ( talk) 18:27, 17 April 2014 (UTC)
![]() | This page is an archive of past discussions. Do not edit the contents of this page. If you wish to start a new discussion or revive an old one, please do so on the current talk page. |
I merged in 100BASE-TX, 100BASE-T, 100BASE-SX, and 100BASE-FX into this collective article. It still needs a lot of work. KelleyCook 18:44, 14 June 2006 (UTC)
utp cat5 consists of 4 twisted pairs instead of 2 —The preceding unsigned comment was added by 81.241.228.203 ( talk • contribs) 05:19, 29 June 2006 (UTC).
Note that today I modified the 100base-FX section to include support for both multimode and single-mode fiber. 100base-FX is called 100base-FX despite what physical media it travels over. You can have 100base-FX over mm OR 100base-FX over single-mode. The only real difference (besides the media itself) is that maximum (and sometimes minimum, research saturation etc) distance you can run. The spec specifically calls out 2km as the maximum distance of multimode for 100base-fx (also 10base-fl), but in the case of single-mode, the distance is entirely based on your optical fiber budget calculated by subtracting rx sensitivity from tx power. Normal SM optical transceivers support at least 10km, and can range up to 110km. Note that you always have to run full duplex over the 412m 100mbps limitation no matter what type of media you employ.
Support for my contention that 100base-fx supports both mm and sm can be verified by looking at Spurgeon's "Ethernet: the definitive guide" page 149. (besides the fact that I have 12+ yrs industry experience, and there are thousands of products on the market that support both mm and sm under the 100base-FX protocol) Kmwiki ( talk) 21:17, 15 January 2008 (UTC)
I've put in the connectors list from 802.3 but it appears there may be other connectors in use, does anyone have any sources for what if any unofficial connectors are common? Plugwash 01:47, 22 March 2007 (UTC)
Plugwash --- I'm not sure about sources, I could probably scrounge some up if necessary.
In the industry, the most common connectors for 100base-FX are either ST or SC, with SC being the most popular. MT-RJ connectors are also used when you are looking for high-density. So, when you need, say (24) 100base-FX ports in a 1U switch, it's almost imperative that a smaller form factor connector be used. With the popularity of gigabit fiber, some 100base-FX devices are even being shipped with LC connectors, the common choice for SFP-based gig fiber solutions. Kmwiki ( talk) 21:05, 15 January 2008 (UTC)
One other thing --- although I didn't remove this, MIC connectors on ethernet devices are pretty rare. Unless you get into some goofy industrial proprietary market, you are unlikely to find a MIC connector on a true ethernet device. Check Nortel, 3Com, Cisco, and you won't find a single vendor putting a MIC connector on an ethernet device. Kmwiki ( talk) 21:23, 15 January 2008 (UTC)
Hi. Is there any good reason why the wiring diagram shows the legacy (non-preferred according to the TIA/EIA-568-B standard) T568B wiring configuration, instead of the recommended T568A configuration? --- Joe. —Preceding unsigned comment added by 61.8.13.206 ( talk) 00:26, 23 January 2008 (UTC)
It is very easy to understand the transmit speed 100Mbps comes from 4 bits at a time, 25 Mhz per second. But, can somebody please tell me, how does a single twisted pair wire transmit four bits at a time (for one direction)? —The preceding unsigned comment was added by 221.169.12.48 ( talk) 16:11, 9 April 2007 (UTC).
Hi, I have been looking for books talking about ethernet physical layer. Now I know the parallel signals in 4 bit wide 25MHz go through a 4B5B encoding before they are serialized and transmmited to PMA sublayer. There is still one thing that confuses me. In the page of wiki talking about CAT 5 cable, it says: "Currently unrecognized by TIA/EIA. Provided performance of up to 100 MHz...". But the PMA sublayer is clocked at 125MHz, how does a CAT 5 cable designed to carry "up to" 100 MHz actually carrying 125Mhz signal in 100BASE-TX ethernet? Is there anything wrong with the page of wiki? Or the signal is actually not transmitted at 125Mhz over the wire? Or is there anything wrong with my understanding?
My understanding is that it actually is transmitted at 125 symbols/s, but the MLT-3 encoding of those symbols makes the worst-case "fundamental frequency" only 31.25 MHz. And that MLT encoding ... somehow ... avoids the bandwidth limitation of CAT 5 cable. If you ever find a good explaination, please put it in the article, OK? -- 75.37.227.177 21:52, 31 July 2007 (UTC)
What does the TX in 100base-TX stand for? —Preceding unsigned comment added by Panarchy ( talk • contribs) 03:58, 26 February 2008 (UTC)
T = twisted pair - not sure what if anything the x stands for here but it does distinguish it from 100Base-T4 Qureus1 ( talk) 07:03, 7 February 2009 (UTC)
in http://en.wikipedia.org/?title=Fast_Ethernet&diff=next&oldid=111062033 soccerman58 claims that there is no such thing as half duplex 100BASE-FX as there is no "need for it". This seems to be contradicted by the relavent section in 802.3 (confusingly they have a general X section which applies to both TX and FX) which explicitly talks about half duplex and is nonsensical (TX and FX both have seperate transmit and receive pairs but both need to be able to run in half duplex mode to support hubs). Plugwash 01:23, 22 March 2007 (UTC)
Just as confirmation, there is most certainly 100base-FX half duplex. You can end up with a duplex mismatch between two ethernet switches, for instance, where one is set to full and the other to half. The Full side would intermittently step on the half side, causing serious performance problems on the link. It's a common task for admins to check the duplex setting on the ethernet switches involved to ensure they are both set to full. Kmwiki ( talk) 20:58, 15 January 2008 (UTC)
My text, Network+ Guide to Networks, explains that in half-duplex mode one strand is used for transmission only and the other for reception only while full-duplex mode uses both the fibers to send and receive data. This text claims that the segment length is limited to 412 meters in half-duplex mode while if used in full-duplex mode the same cable can be 2000 meters. If true, why would the mode affect the segment length like this?
Qureus1 (
talk)
07:02, 7 February 2009 (UTC)
What are the maximum physical and logical sizes of 100Base-TX LANs?
If one segment can be 100m, then two endpoints can be 200m apart, via one switch. But switches can be chained/cascaded, so the maximum distance could be increased. What is the limit?
(Note also the difference between theory and reality. Some equipment works better over real cable segments, some worse. So the 100m segment limit is fuzzy. Some equipment may auto-negotiate down to lower speeds when there are cable problems, but still function somewhat.)- 96.237.78.13 ( talk) 02:46, 25 August 2010 (UTC)
As part of the same edit mentioned about a mention of single mode fiber was added to the FX standard, later a bracketed 100BASE-LX was added after this. Is this an unoffical standard? an unofficial name for using a fiber type that is out of spec but works? something else? Plugwash 01:47, 22 March 2007 (UTC)
Plugwash, if its any consolation, I've never heard of 100base-LX, now 1000base-LX is a different story.
The common ethernet standards are currently (beginning 2008):
(10mbps finally being phased out at the chip level due to ROHS european elimination of lead-based stuff)
10base-5, aka 10mbps Thicknet
10base-2, aka 10mbps Thinnet
10base-T, aka 10mbps Twisted-pair
100base-TX, aka 100mbps twisted-pair
100base-FX, aka 100mbps over fiber
100base-SX, UNPOPULAR 100mbps over mm fiber only standard, 300m maximum, cheaper 850nm optics.
1000base-SX aka gigabit over mm
1000base-LX/LH aka gigabit over SM (usually, unless you use a mode-conditioning patch cable on both sides and run it over mm)
1000base-ZX aka gigabit over sm super long haul.
Don't ask me about 10gig yet. :)
Kmwiki ( talk) 21:34, 15 January 2008 (UTC)
100BASE-LX10 is described here now, along with 100BASE-BX10; yes, that's what IEEE 802.3-2012 calls it, even though both can, apparently, run over distances > 10 km - the spec says "The 100BASE-LX10 and 100BASE-BX10 PMD sublayers provide point-to-point 100 Mb/s Ethernet links over a pair of single-mode fibers or an individual single-mode fiber, respectively, up to at least 10 km." (emphasis mine), and some Googling finds references to 100BASE-{B,L}X20 and so on. Guy Harris ( talk) 18:27, 17 April 2014 (UTC)