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LAN cable: how long is "too long"?

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November 4, 2006 1:53:07 PM

i've got a wired router connecting several devices

when connecting devices to the router, is it possible to use a cable SO long that it degrades performance?

if so, what's the maximum length of cable i should consider?

More about : lan cable long long

November 4, 2006 2:24:04 PM

Quote:
i've got a wired router connecting several devices

when connecting devices to the router, is it possible to use a cable SO long that it degrades performance?
Yes.

Quote:
if so, what's the maximum length of cable i should consider?
100 meters for each run from the router.
November 6, 2006 4:48:34 PM

Signal loss is referred to as Attenuation.

Cat 5 is 285 feet.
Cat 6 will go to around 700 feet or something of that length. The longest I've run of Cat 6 is 630 feet.

The longer the cable, the longer it takes for the data to get there. (its a joke)

Most of the time in your home, you can get away with Cat 5. If you start pushing 250 feet, you may want to move on to Cat 6. 6 is slowly replacing 5 right now and you might as well spend the extra penny to go with it.
Related resources
November 6, 2006 6:50:47 PM

Quote:
...Cat 5 is 285 feet.
Cat 6 will go to around 700 feet or something of that length. The longest I've run of Cat 6 is 630 feet....Most of the time in your home, you can get away with Cat 5. If you start pushing 250 feet, you may want to move on to Cat 6. 6 is slowly replacing 5 right now and you might as well spend the extra penny to go with it.
Says who?

Cable specifications for the 10-Mbps 10BaseT cable with RJ-45 connector:
Category 3 or Category 5 UTP with 22 to 24 AWG
Maximum segment length ..... 100 m (328 ft.) for 10BaseT
Maximum network length ....2,800 m (9,186 ft.) (with four repeaters)

Cable specifications and connection limits for 100-Mbps transmission, RJ-45 connector.
Category 5, UTP, 22 to 24 AWG
Maximum segment length .... 100m (328 ft.) for 100BaseTX
Maximum network length .... 200 m (656 ft.) (with one repeater)

Of course, it doesn't drop off the earth at 100.1m, so you can get away with pushing the limits of the spec in many cases. Network timing also comes into play for large, long networks, which can increase message collisions and therefore reduce throughput.
November 10, 2006 5:03:41 PM

The limit is 100meters/328 feet for cat 5/5e/6. The other numbers you hear 285/295ft etc are based on 1-5meter cable connection between switch/hub/patch panel and server/computer. You can stretch the limit just dont overdo it.
November 11, 2006 3:49:29 PM

Correction
Cat 5e (1 Gigabitps) is 75m actually.
Cat 5/6 is 100m
November 11, 2006 7:44:58 PM

its 100 meters for all 3 cat 5 has 100ohm att vs200-250 for cat 5e 5e and 6 have better specs performance wise but still limit is 100 meters. its all based on eia/tia standards. difference for gb is that it uses all 4 pairs of wire vs 2 for 10/100
November 12, 2006 1:35:03 AM

OK here are the specs straight out of the COMPTIA book as I literally was in the course as I posted

Everything all the way from Cat3 was ALWAYS 4 pairs of twisted Wires
Cat 5 is 100BaseT (100 Mbps w/ 100 m range)
Cat 5e is 1 Gbps (1000 Mbps) w/ a 75m range

Cat 5e ONLY has a 100m range if you get Base-TX. (Not base T)
Cat 6 is 100m and supposedly can do over 1.2 Gbps but...thats the spec.

That's the real, hard specs. No room for interperation or arguement. I'm reading it straight out of the 2006 Comp TIA book.
November 12, 2006 2:56:13 AM

Nice information, but would you please explain, Mr Wolf, the difference between Base-T and Base-TX and how does that affect the cable?

While you're at it, which of those is used on standard 100Mbps NICs? And, which is used on standard 1000Mbps NICs?

And, which was the one our OP was actually asking about?
November 12, 2006 11:53:15 AM

Ice,
I actually don't know the physical difference between T and TX, the book is too far away to look it up. I do know that it was a test question on our practice test, and the answer was T = 75m and TX=100m. I'm assuming its something as simple as a more pure-copper set of wires, or perhaps a different alloy of metal than just copper. Perhaps it also has thicker rubber for better EMI/signal shielding.

All of these cables use an RJ-45 style ethernet connector and will fit into any Ethernet NIC. A 100Mbps NIC obviously can use them all, but its not going to transmit any faster than 100Mbps so there's no point in using Cat5e or Cat6.

If you have a Gigabit (1000Mbps)NIC, then before you go and get Cat5e or 6 cable, ask yourself what you'll be doing. We all know your broadband net connection will never DREAM of getting up to 100Mbps even. The ONLY instance where Cat5e or Cat6 would benefit a home user is if A) He wanted a LAN of several computers in home B) they ALL have Gigabit NICs C) they were networked together with a Gigabit switch and D) ALL cable used was Cat5e or Cat6. In this scenario, the comps on the network WOULD take advantage of gigabit if they were talking to eachother for info, such as LAN games. But as far as reaching the internet goes, the Gigabit would show no advantage for any of the computers.

The OP didn't make a reference to any specific style of cable or NIC.
OK there's a lesson straight out of the A+ hardware certification course, that'll be $100 for each reader plz. Just PayPal me. :-)
November 13, 2006 12:10:08 AM

It was a test, Mr Wolf, not an inquiry. There is a difference between data and knowledge.

Find a 100Mbps NIC for a PC that is NOT Base-TX. Let me know the model number.

Chances are near 100% the distinction between Base-T and Base-TX makes no difference whatsoever to the OP's question.
November 13, 2006 2:56:25 AM

I believe you mean there is a difference between data and experience. As data and knowledge are the same thing. All I did was post the data. The data is correct. I didn't say who is right, who is wrong, what NIC's use what cable, etc. I just posted data straight from the book. Take it or leave it, no sense in arguing fact, Mr. Ice. I don't care if most NIC's use TX...Maybe they do, maybe they don't. I just posted what the range of different types of cables are. Seeing as how that is what the OP asked (Maybe he wants 5e, maybe he doesn't) that is what I answered.

Whatever Mr. Ice, I believe both of your recent posts directed towards me were rather snotty sounding...and I'm not quite sure why. Who knows it could be something as silly as a subconscious aggression that only a pyschiatrist could explain. Either way..The OP wanted to know the range of the cable. Since he didn't have a specific one posted, I gave a few different examples. All examples are fact, nothing else. So, in fact, I believe my post answered the OP 100%.

Ok that's the last look I'll take at this thread, Mr. Ice.
November 13, 2006 4:04:53 AM

No, knowledge and data are not the same thing. Your data was correct, but the knowledge to answer the question without muddying the water was missing.

I didn't mean to offend, but rather was hoping you would see where I was pointing you without me directly and bluntly calling your answer misleading. You didn't see or didn't understand. I don't know which, but I suspect you may not even know the difference between "T" and "TX" and what it signifies.

Virtually all 100Mpbs so-called "fast ethernet" LANs are 100Base-TX with Cat5 or Cat5e cable and RJ-45 connectors.
November 2, 2007 4:13:25 PM

Dear 'I',
Read your chat with Mr. Wolfe. We ran a Cat5 from one building to another, about 550-575', not aware of the length restrictions. Wireless is not an option 'I', as there is too much noise. (Transformers)
'I', can you recomend any type of signal booster to get us up, or are we F'd, and forced to replace it with Cat6?
I appreciate your input 'I'.
Thank you.
July 18, 2010 1:19:12 PM

Hi All
I m running an external cat5e cable from a thompson v585 modem to a network switch , length 90 meters. When i connect a laptop to the other end internet connection is fine. Download speed of 8mbps upload 350kbps, However when i connect any network switch (pluscom 16 dual switch) the ethernet led flashes slowly and internet does not work, also tried connecting 3 other switches with the same results.. Tp link switch connects but interent connection is not stable with virtualy no upload...have i exceed cat5e permissible cable length??? my hardware store says up to 100 meters is good???? Will i solve the problem by replacing with cat6 cable??
July 23, 2010 5:27:56 PM

thread resurrection....

can you verify that the switched work with a short cable? it might be a better idea to get two 45m cat5 cables and put the/a switch in the middle to act as a repeater.
July 24, 2010 9:32:04 AM

Yes, With short 5 meters cables everything is fine.. Just cant believe that everybody quotes that cat5e can run up to a max of 100 meters and my hardware stores says that he even used it up to 130 meters without problems!All i have is 87 meters to be exact!I ll have to do a repeater switch in the middle. The only problem is that the cable runs on roofs of 3rd parties. Will have to run an electricity extension and put another switch in a waterproof box
July 24, 2010 12:28:17 PM

People quote 100m because that is the specification for that type of cable. Yes it is possible to exceed this but there are many variables that play into that. Just because someone got lucky with their run that exceeds the spec doesn't mean everyone will.
August 20, 2010 2:22:18 AM

Kaa is right. The environment that you install ethernet into has a lot to do with the distance, performance and PoE power (if used) that you get on the remote end. Just because a person or vendor claims a distance is no guarantee that you will get it.

Possible factors to consider are:
* The quality, length and copper composition of the cable
* Any electromagnetic interference (fluorescent light ballasts, A/C in business false ceiling areas, fans/motors, and other electronic devices).
* Whether a cable has been spliced or is all one piece. Patching cables together into switches, wall plates and couplers can degrade the connection and signal.

Don't forget that there are now good Ethernet extenders out there that are better and less expensive than some switches and repeaters. There are even gigabit Ethernet repeaters now (see the Enable-IT 828) and some that go up to 6000 ft! Check the specs carefully on these as they vary greatly. Maybe Tom's Hardware will do a review on these sometime or someone that's used one will share their experiences.

Good luck!
October 21, 2010 8:48:55 AM



"Everything all the way from Cat3 was ALWAYS 4 pairs of twisted Wires"



Bit late now and no one will read this - The cable has 4 pairs but a 100BaseT network only uses 2 pairs (normally greens and oranges) - try connecting your PC to your router and snip the browns and blues - it will work - I use this quite often on old installations if customers don't want pay for new cable - I pick up the spares in a network point and join.

August 24, 2011 5:49:21 PM

92Katz said:
Dear 'I',
Read your chat with Mr. Wolfe. We ran a Cat5 from one building to another, about 550-575', not aware of the length restrictions. Wireless is not an option 'I', as there is too much noise. (Transformers)
'I', can you recomend any type of signal booster to get us up, or are we F'd, and forced to replace it with Cat6?
I appreciate your input 'I'.
Thank you.


Honestly if you are going that kind of distance you should be using fiber not cable. If you are in a lightning prone area you definitely do not want to put cable above ground or you run the risk of losing your network because that line will be a lightning magnet much more so than a telephone or electrical line.

Bite the bullet, spend a little money and do it right, have a fiber line dropped in and be done with it.
September 25, 2011 4:00:12 AM

galtiero said:
Honestly if you are going that kind of distance you should be using fiber not cable. If you are in a lightning prone area you definitely do not want to put cable above ground or you run the risk of losing your network because that line will be a lightning magnet much more so than a telephone or electrical line.

Bite the bullet, spend a little money and do it right, have a fiber line dropped in and be done with it.


Wait a minute, mr Iceberg smart ass before said that there is nothing in this world at 100mbps other than RJ45!
January 8, 2013 10:38:21 PM

The truth for cable lengh its ,,,

1- in a switch of 24 port or in a switch of 48 port or 1 million port only one computer talk at the same time,
switch mean complete or connect one point to other point, so a cable only has begin and end,, so only
2 computer one talking and the other listening.

2- when one computer is talking guest what? the others are waiting,,,and guest what

3- The velocity of the electron and the time for a computer waiting are the truth,
when an electron reach 328 feet walaaa the time is ready for other pc to begin talk

so in 1980 328 feet in 2013 328 better techology to built the cable..
jaja the electricity in 1980 and 2013 travel at the same speed jeje

cable thru neon bulbs what they did to the electron,,easy get the electron litle slow so
its aparent that cable is more long.

February 15, 2013 12:14:28 PM

I somewhat agree with what candelario_e is saying and what others have said, but I thought I would add my $0.05 (since they just eliminated pennies here in Canada) from an Electronics Engineering Technologist *and* Computer Science perspective:

1. There is a physical link spec, that is where the different cabling specs come in. As we got faster physical link speeds, the signalling rate on the wires had to increase as a result, hence the need for better specifications for the cables themselves. (Note I did not say BAUD rate, as there likely are encoding schemes involved, just like in RF.) The number of conductors and so on are the same, the RJ-45 connectors are the same, but the impedance, twists/length and the requirements at the crimp end etc. have changed. The old wires will plug in and work for short lengths, but you may have lost or corrupted signals meaning lowered throughput from retries. The wire could be a limiting factor in terms of attenuation (signal loss) over distance, but typically you hit walls in other areas first. This is where the original repeaters were used, but they only boosted the signal, they didn't have intelligence and buffer and re-create the signal per se. This is also where using fibre helps, light travels much faster and as a bonus is immune to RFI / EMI (and a lot of environmental concerns like water, humidity, temperature and so on). This plays into what I discuss in #2. As an aside, more rubber may attenuate interference a slight bit, but it is more the shielding and proper twists that helps with immunity to interference in a twisted pair cable.

2. There is a signalling specification which defines timing and maximum "windows" in which signals must be received to be considered valid. Where candelario_e was saying is that the electrons travel at the same speed, no matter what the cable length. If you put too long of a segment in, you violate the timing constraints of a valid Ethernet conversation (CSMA-CD) even though only one unit talks at a time (except possibly in full duplex mode). The frames get lost or corrupted and retransmissions and possibly even collisions increase because of these timing problems. (Station B is listening because it wants to transmit, all is silent, so it begins transmitting, but just as it does, the signal from Station A arrives because the cable was too long, oops, collision, set the back off timers and start again.) There comes a point where it is unworkable and virtually no data gets through. Ethernet does *not* have all the same numbering and sequencing and retries that a higher level protocol has. It only tries a frame a small number of times before giving up. Now if you use fibre, since light travels faster than an electromagnetic signal in a wire (about 40-70% of the speed of light in twisted pair), even with the same signalling timing, you can go further.

3. #1 and #2 are the Ethernet levels, there are the protocols on top of that, nowadays typically TCP/IP. It has checks and retries and all that built in for reliability, however having to do all of that because of problems at the lower level reduces the *real* data throughput and makes the connection "slow".

4. The advent of switches changed the whole "maximum number of repeaters" and "maximum length" scenario. A switch takes the signal in as an end-device (much like a PC or router), it then starts the sending process all over again on each segment it intends on sending it down. Therefore each connection is subject to these maximums. The only limit to length becomes the timing of the overlying protocol. At past companies, we did a similar thing and wrapped TCP/IP packets into our own protocol with huge timing windows to move data over the satellite network. Each end thought they were talking to each other, but in reality, they were talking to our devices, which talked our own protocol in-between them. Of course, if you put something more intelligent than a switch (or a Level 3 switch) in-between, then they do the same thing for TCP/IP (or whatever higher level protocol) as switches do for Ethernet, which is how we can connect the Internet around the world and beyond. (Think International Space Station.... yes, they do data and VOIP.) This is also how those "magic" long-haul ethernet boxes work. They use their own proprietary signalling and protocol between their boxes which was designed to work over the longer distances.

I hope I haven't really confused anyone like I often do when I try to expose the underlying truths. Oh and by the way, the CompTIA people aren't overly technical, their business is to write the exams and books, just like what you read on the Internet, always consider the source of your information before putting your reputation on the line based on it. Check out the specifications from EIA/TIA and IEEE and the other organisations who are behind the technologies and trust that way before a "Readers Digest" version that wants to give you the easy answers.

Oh and where candelario_e is wrong, many devices can talk simultaneously in a multi-port switch with a true switching fabric, as each port acts like a separate device with its' own buffer etc. That is why the switch fabric is rated for slightly over the combined speed of all of the ports in a decently engineered switch.
February 15, 2013 1:02:20 PM

wolfman140 said:
OK here are the specs straight out of the COMPTIA book as I literally was in the course as I posted

Everything all the way from Cat3 was ALWAYS 4 pairs of twisted Wires
Cat 5 is 100BaseT (100 Mbps w/ 100 m range)
Cat 5e is 1 Gbps (1000 Mbps) w/ a 75m range

Cat 5e ONLY has a 100m range if you get Base-TX. (Not base T)
Cat 6 is 100m and supposedly can do over 1.2 Gbps but...thats the spec.

That's the real, hard specs. No room for interperation or arguement. I'm reading it straight out of the 2006 Comp TIA book.


Not to hammer the point too much here. But I have taken the Network+ in the past, and try to keep up with the current books. CompTIA seems to keep changing what they say. Yes you are right, the latest Network+ book does say 75m for Category 5e, Previous editions said 90m, and 100m for 5e.

In practice, I have run 125m runs of category 5e cable with no loss of signal that switches haven't been able to compensate for, however inductive interference on a cable that long can become a problem. It's not a good idea, but the guy that was paying me to do the work said he didn't care and do it... It worked, but wasn't right.

Honestly, it is sort of moot. Unless you have boxes of cat 5e, for the cost difference you might as well pull cat 6 anyway... Same work, $10.00 - $20.00 a box difference in cost. Big whoop...

So back to the OPs question. What is the longest cable length he can run without degrading performance? My answer is, it all depends. But the general rule of thumb accepted by most all networking professionals is 100m for category 5, 5e, and 6. Try to make your runs clear of anything that can create inductive interference on your cable such as high voltage power lines, amplifiers, microwave ovens etc...

If you are wondering about a residential application, unless you live in a mansion, or are running a cable from the house to a separate building like a shed converted into an office (don't laugh, I have 4 of my neighbors doing this, they work at home and having their office separate from the house keeps the kids out of their hair while they work), you will never run into a situation where cable length is going to be a problem.
February 17, 2013 4:49:11 PM

As dbhosttexas says, the answer for the OP is "depends" and what works (today) may not be what's right.

The primary reason for the maximum lengths is that 1) what gets the message across eventually is not necessarily what is getting the full speed from the link with minimal collisions and retries, 2) what works today pushing the edge isn't necessarily going to work tomorrow with voltage differences and changes to interference with new devices in the area of the cable run and 3) as I've found in the past with dental office installs, even being within the specs isn't enough when there is large amounts of interference (x-ray machines) present. So really, there are guidelines, but no hard-and-fast rules.

I generally run a bunch of traffic through the link and check smart switch statistics afterward, as in how many collisions, how many dropped frames and so on to see what the quality of the link is, not just "is some traffic getting through". Sort of like we run BER tests on telco links to see if they are working properly.

Oh and since it appears we are throwing credentials around, MCSE, CNE, A+, Network+, CCNA, Electronics Engineering Technologist (the people who design the network cards etc.), Bachelor of General Studies in Science (Comp Sci.) and a bucket load more that I've forgotten about since 1986 when I started doing this "for real", 1978 if you include first introductions to *nix like systems on a casual basis. I guess I need to do my profile.
August 15, 2013 11:15:48 AM

Just ran CAT6 cable from a Gigabit PoE switch in the NOC a distance of 300+ feet to a PTZ camera that uses 720p resolution. We could not get a video signal at this length (but could see the IP address) so we put in a switch at the end of the run right next to the camera to amp the signal and it now works fine. Specs are specs but until you actually implement in the field and account for all variables, such as equipment you are using, noise, etc. you will not know for sure.
October 14, 2013 12:06:34 PM

Old thread but I know what the differance is between base -t and base-tx. Because I was pulling cable when it became big.. tx is for full dupexing, it only works wit a tx nic connected to a tx switch connected to a tx server and there was a shorter workbable length.
December 17, 2013 2:11:41 PM

Here is the thing about a 300m limit; if you are terminating a full duplex computer NIC on one end, and a full duplex switch on the other, then collision detection becomes irrelevant as there are no collisions, ever. In that situation your length limitation is a function of signal loss and noise, not collision detection and if you have high quality cable and a low noise environment, you can get away with more distance. The same is true if you've got full duplex switches or routers terminating each end. As long as it's full duplex and not a hub, you can do it. Beware of routers with built-in hubs, built-in switches are okay. If you are doing half-duplex and/or hubs on either end where collisions can happen, then you need to stay under 300m regardless of cable quality.
December 29, 2013 1:41:52 AM

hi yourtboy,

max 100 meter you can used for excellent communication
January 19, 2014 7:06:45 AM

Merely wish to say thank you so much Mr Canada (HW_SW_Tech_1986). Je vous remercie infiniment.

As a student of IT at an early level I've searched for a deeper, an underlying, understanding of LAN's, and the internet's, workings. While progressing through your first offering I've been exclaiming, " Oh! Right! I see!", again and again. It has given to me all the info I want to add as an extra to last terms assignment which I'm submitting late.

Every bit as useful, your mini dissertation, and its sequel, provided almost completely the information I need in my battle with my ISP, and the infrastructure it uses, Open Reach|BT, whose exchange is too far from our 2000+ homes, and therefore even more users, 4.6 km of copper-wire-cable, for my studies from home. Hence my search as to whether some boosting device can be installed in a roadside-cabinet at around 2.5-3.0 km, and your info seems to indicate that this is possible if the owners of the infrastructure are willing.

Your explanations were credentials in themselves, being logical, falling into place with my previous, other, studies.

Again thanks so very much.
6 minutes ago

riser said:
Signal loss is referred to as Attenuation.

Cat 5 is 285 feet.
Cat 6 will go to around 700 feet or something of that length. The longest I've run of Cat 6 is 630 feet.

The longer the cable, the longer it takes for the data to get there. (its a joke)

Most of the time in your home, you can get away with Cat 5. If you start pushing 250 feet, you may want to move on to Cat 6. 6 is slowly replacing 5 right now and you might as well spend the extra penny to go with it.



Umm i'm prettysure the specified limit for cat is is 100 metres and can be pushed to a max of 120 at which point there will be considerable signal loss so i would like to know where you got the 700feet figure from and if there is another easily availabe network cable that delivers that so it woud be convenient
!