Is Your Cat 6 Cable a Dog? (2013)(bluejeanscable.com)
bluejeanscable.com
Is Your Cat 6 Cable a Dog? (2013)
http://www.bluejeanscable.com/articles/is-your-cat6-a-dog.htm
115 comments
Why is 6 not useful and why is 5E/6A better?
6 is useful for non-dense high-bandwidth environments where you might need to get 10G-BASET a little further than 5e will manage, but 6 doesn't address enhanced alien crosstalk. This means in dense environments it may struggle. 6A does, via shielding, and so will work better in dense environments (where you're likely to see 10G-BT anyway).
Isn't shielding separate from the category? I recall seeing stuff like Cat5 FTP and Cat6 STP or some combination like that. I'm no cable expert, but from what I understand, STP means shielded and FTP has some other kind of shielding.
I think I put Cat6 STP or FTP in my home. Whichever it was, I wanted to have the best cable I could possibly find, because I don't want to have to redo this every 10 years.
I think I put Cat6 STP or FTP in my home. Whichever it was, I wanted to have the best cable I could possibly find, because I don't want to have to redo this every 10 years.
Shielding's optional for 6A so be careful where you buy if you want that.
If for no other reason, price - why pay more for something that's not any better than 5e?
I've always found 6 cheaper than 5e, or at least the same price. And why not give myself some extra headroom?
Firstly, I should have been clearer that I specifically meant cat6a, rather than cat6.
I haven't actually bought an ethernet cable for several years now, but cat6a always used to be quite a bit more expensive than cat5e. I just had a quick look, and here in the UK it seems it still is, at least for shielded cables:
I haven't actually bought an ethernet cable for several years now, but cat6a always used to be quite a bit more expensive than cat5e. I just had a quick look, and here in the UK it seems it still is, at least for shielded cables:
- 30m UTP cat5e cable is £12
- 30m STP cat5e cable is £47
- 30m UTP cat6 cable is £14
- 30m STP cat6a cable is £100Its not that 5E is better, its about the application. Either you need near full length runs of 6A for 10G, and you need to have it carefully terminated (which is a large problem in a lot of installs, more so than the actual cable) or you have short runs which will work just as well over just about anything that isn't completely screwed up.
Maybe another way to put it is this: doing a poor CAT6 install (as this article points out most are) isn't buying you anything over cat 5E, your spending money for nothing.
Maybe another way to put it is this: doing a poor CAT6 install (as this article points out most are) isn't buying you anything over cat 5E, your spending money for nothing.
There is the 2.5 and 5 GbE standards (https://en.wikipedia.org/wiki/2.5GBASE-T_and_5GBASE-T ), where 5 Gb is specified for Cat 6.
But yes, previously there wasn't much point to it. Cat 5e is good enough for 1GbE, and for 10GbE you need Cat 6A.
But yes, previously there wasn't much point to it. Cat 5e is good enough for 1GbE, and for 10GbE you need Cat 6A.
How long is "long" in this context? 5ft? 50ft?
10GBASE-T over Cat 5e works pretty well up to 100 ft and 150 ft is doable if you carefully run avoiding electronic noise sources (like a wall power outlet).
NBASE-T IMO is much more interesting for end users because by now USB adapters for those should be out and I fully expect them any week to drop. 5gbit/s runs up to 300 ft on Cat 5E. Also, while five gigabit is certainly doable for laptops with NVMe disks (last three years, since Skylake), ten gigabit is not necessarily so if you have PCIe 3.0 x2 (or equivalent) bottlenecks here and there. See, many Intel U chip laptops run the on chip bus between PCH and CPU at only a PCIe 3.0 x2 equivalent speed (aka 16 gbit/s) and the U chips provide PCIe lanes only off the PCH so if your data streams needs to cross into the CPU and if you are burning 10 out of the 16 for just Ethernet, not a lot will be left. And most of the time you need to cross the On Package Interconnect because the system memory hangs off the CPU side of it and all the peripherals the PCH side of it (northbridge vs southbridge, to use older terms). There's no such problem with 5gbit/s, you can even put twice of that on a 2GT/s OPI and still have bandwidth to spare.
Another potential such bandwidth choking point is the Thunderbolt controller, althought that might be past by now, because there is no JHL 7240 or Titan Ridge LP -- there was an Alpine Ridge LP which only used a PCI 3.0 x2 connection to the host meaning if you wanted to have a 5gbit/s USB A connection on your dock and you wanted 10 gbit/s Ethernet, you are already hitting all the constraints. Once again, 5gbit/s eases this problem.
In about five years when PCIe 4.0 and USB 3.2 are ubiquitous, well established features in laptops, that's when we can begin to discuss whether ten gigabit makes sense at home/small office.
NBASE-T IMO is much more interesting for end users because by now USB adapters for those should be out and I fully expect them any week to drop. 5gbit/s runs up to 300 ft on Cat 5E. Also, while five gigabit is certainly doable for laptops with NVMe disks (last three years, since Skylake), ten gigabit is not necessarily so if you have PCIe 3.0 x2 (or equivalent) bottlenecks here and there. See, many Intel U chip laptops run the on chip bus between PCH and CPU at only a PCIe 3.0 x2 equivalent speed (aka 16 gbit/s) and the U chips provide PCIe lanes only off the PCH so if your data streams needs to cross into the CPU and if you are burning 10 out of the 16 for just Ethernet, not a lot will be left. And most of the time you need to cross the On Package Interconnect because the system memory hangs off the CPU side of it and all the peripherals the PCH side of it (northbridge vs southbridge, to use older terms). There's no such problem with 5gbit/s, you can even put twice of that on a 2GT/s OPI and still have bandwidth to spare.
Another potential such bandwidth choking point is the Thunderbolt controller, althought that might be past by now, because there is no JHL 7240 or Titan Ridge LP -- there was an Alpine Ridge LP which only used a PCI 3.0 x2 connection to the host meaning if you wanted to have a 5gbit/s USB A connection on your dock and you wanted 10 gbit/s Ethernet, you are already hitting all the constraints. Once again, 5gbit/s eases this problem.
In about five years when PCIe 4.0 and USB 3.2 are ubiquitous, well established features in laptops, that's when we can begin to discuss whether ten gigabit makes sense at home/small office.
This is just more market segmentation. There isn't any reason that 2.5 or 5Gbit couldn't have been optional extensions to the 10Gbit standard other than to further segment the market.
Particularly as we are discussion cables, it should have just been a case of, oh we see your 250ft run doesn't' appear to be running without errors lets drop it down to 5gbit, or this link is running at 10% utilization lets save some power and drop it back to 2.5Gbit.
Particularly as we are discussion cables, it should have just been a case of, oh we see your 250ft run doesn't' appear to be running without errors lets drop it down to 5gbit, or this link is running at 10% utilization lets save some power and drop it back to 2.5Gbit.
I think the reason is more historical than artificial market segmentation. Long ago, the development of Ethernet technologies was targeted to achieve an increase of a factor of 10 for each subsequent generation, i.e. 10m->100m->1g->10g. The need for 2.5Gbit and 5Gbit only came with 802.3ac Wave2 devices, where a Wave2 MIMO AP can saturate a 5G pipe after subtracting WIFI overhead.
Also, 2.5G/5G Ethernet actually did not start out as an IEEE specification, but was started as NBASE-T/MGBASE-T.
From what I remember, the 2.5G/5G/10G devices actually will negotiate to determine the maximum datarate that will work.
Also, 2.5G/5G Ethernet actually did not start out as an IEEE specification, but was started as NBASE-T/MGBASE-T.
From what I remember, the 2.5G/5G/10G devices actually will negotiate to determine the maximum datarate that will work.
Many new chipsets (Aquantia comes to mind) are indeed multispeed (10-5-2.5-1-.1) but I am not sure whether it is capable of such intelligent speed settings.
My experience is that your probably safe at 50ft and below. Which is actually the max cable lengths tested in this article. For single switch->switch runs in a non critical environment (say my house) I would personally push it as far as I could get away with rather than replacing a cable simply because it doesn't happen to be officially sanctioned.
What might have been more interesting is if they plugged those failing cables into a few switches to see if they actually were having problems anywhere. I'm betting they were probably mostly working fine. Although I have to wonder how many people are buying cat 6/6A for "future proofing" rather than actually running 10G on it.
What might have been more interesting is if they plugged those failing cables into a few switches to see if they actually were having problems anywhere. I'm betting they were probably mostly working fine. Although I have to wonder how many people are buying cat 6/6A for "future proofing" rather than actually running 10G on it.
I posted this below, but I think it's also good here, because it's a fun anecdote. I have a 10Gig run on 200+' of Cat5E in production that works well with only a few hundred errors a year. Running fiber or Cat6A into that room would costs thousands. This is mostly a credit to the interface designers, who let us get away with stuff that we totally shouldn't.
The Cat5E run is nearly perfect, entirely away from power lines, and clean direct from one room to another.
The Cat5E run is nearly perfect, entirely away from power lines, and clean direct from one room to another.
If your running direct port->port you get a lot of additional margin because the plug->jack is where a lot of the loss comes from and the assumption in the spec is that a run looks like "port jack->patch cable->panel jack->solid fixed run->jack->patch cable->end port".
So if your cable run is "port->long solid conductor cable->port" its going to give you some extra feet.
So if your cable run is "port->long solid conductor cable->port" its going to give you some extra feet.
Solving the random issues that result from going beyond the specs of the cabling is the worst. It works for months and then suddenly fails for no reason.
This hasn't been my experience with copper. It tends to work until someone breaks it. Optical SFP's OTOH, were my bane for many years as they do frequently degrade leaving a once perfectly functional link dropping some huge number of packets before anyone notices that the link has degraded to some 1980's level of speed. Port monitoring when your not a network provider, or big data center seems to be a "hard" problem.
I buy a lot of cables for work. A few years ago I tried to order a new batch from my supplier and they told me they now had CAT6 for the same price, but thinner. So since 2015 or so we've used CAT6. But never in lengths that matter, just in-rack patch cables. Initially I didn't really care about the diameter. Later we ran out of space in the cable trays where we had some older, thicker stuff and swapping it out made a tactile, physical difference. IMO 5/5e/6 is a wash anyway, if you need distance you probably just need fiber.
I ran “Cat6” in my house, and followed the Cat6 guidelines. It's not because I realistically expect Cat6 performance — it's because I want Cat5e performance, and expect that vendors lie out of their ass, and hope that going ‘one better’ is enough.
If you're ripping open your walls to do it, the difference in cost between 6 and 5e is probably a rounding error, and there's a strong desire to do it once.
I have costed it. The cable itself is indeed a rounding error. I would suggest getting plastic piping installed with the cable inside and some strings. Then you can pull more cable when need to.
Perhaps it not comply to USA regulation but for my home I opt to design custom interior wall (simple commercial iron profile instead of classic plasterboard structure) and countertops with wood planks and joint covers (from nearest wood store) so I can open nearly anything and nearly anything look like reasonably well.
Interior walls are simply heavy cut-ed 60x30x1.5mm vertical beams with horizontal ligatures made of flat iron 40x2mm covered with "insulation scotch" for noise reduction purpose. Wood planks are coupled vertically three/four maximum in the garage with a simple bar to hang furniture as a horizontal joint. Skirting and ceiling joint covers permit insertion and remove thank to the interior "female side" of the last wood planks cut-ed out before mount.
It was far more complex than what I consider at start (and I still have to finish many parts) but IMO it's cheap, good-looking and comfortable enough to being worth it. With that any kind of implant can be accessed directly without brake anything and when it's time to repaint it can be done again in the garden/garage instead of cover up anything inside...
Interior walls are simply heavy cut-ed 60x30x1.5mm vertical beams with horizontal ligatures made of flat iron 40x2mm covered with "insulation scotch" for noise reduction purpose. Wood planks are coupled vertically three/four maximum in the garage with a simple bar to hang furniture as a horizontal joint. Skirting and ceiling joint covers permit insertion and remove thank to the interior "female side" of the last wood planks cut-ed out before mount.
It was far more complex than what I consider at start (and I still have to finish many parts) but IMO it's cheap, good-looking and comfortable enough to being worth it. With that any kind of implant can be accessed directly without brake anything and when it's time to repaint it can be done again in the garden/garage instead of cover up anything inside...
I'm surprised by this. I guess i'm just used to having an attic or false ceiling. In both cases you just drill a hole in the top of the wall attach a cable to a cable snake and push it down the hole 6 feet, punch a hole where you want the jack and fish the snake out. Bonus if you squirt some foam into the top hole when your done to keep the air/critters out of the wall. Wiring most rooms/etc is a breeze if you don't get to picky about where the jacks are.
These days with the prevalence of wifi that's not even necessary. Very often in a house a couple ceiling mount AP's, a drop to an entertainment center and into the study is about all I was motivated to do in my most recent house.
The cable/telcom providers though are the worse. The standard operation seems to be running a cable around the outside of a house and just punching right through the wall.
These days with the prevalence of wifi that's not even necessary. Very often in a house a couple ceiling mount AP's, a drop to an entertainment center and into the study is about all I was motivated to do in my most recent house.
The cable/telcom providers though are the worse. The standard operation seems to be running a cable around the outside of a house and just punching right through the wall.
That method indeed works nicely for a simple ranch in a nice climate. It doesn't work as well when you have multiple attics, vaulted ceilings, multiple floors, and twenty inches of attic insulation.
Damn, that's a good idea. I wish I'd done that for my new house. I'm beating myself up for not running enough cables between rooms. Not sure if I'm able to pull more wires (sometimes they tie the wires down to the frames)
I've been buying Blue Jeans cables for a long time (starting with audio/video cables, and more recently Cat6) because I love their no-b.s. attitude. And if you're in Seattle and ask nicely they may even let you drive over and use their fancy tester on your existing cables.
On the A/V side their story was basically "this is the same cable that the studio that made the content you're watching is wired with, and you don't need anything more than that".
On the A/V side their story was basically "this is the same cable that the studio that made the content you're watching is wired with, and you don't need anything more than that".
I guess the article isn't dated but judging from the Internet Archive it should have a [2013] tag. http://web.archive.org/web/20130727071218/http://www.bluejea...
Thanks–updated.
They kinda gloss over one point - the ones that passed/semi-passed are the short ones.
For a 1m patch cable noise rejection, cross talk & similar length isn't really an issue.
Like it or not manufacturers get away with it because in the vast majority of situations a cat5 or even a failing cat5 has no real world consequence. It fails the standard yet still works in practice - on a physical level. Plus the network stack built on top of that has further fault tolerance.
If it's a long cable at the edge of tolerance or you're in a mission critical datacenter then yeah maybe worry about this stuff. Everyone else just grab a patch cable off amazon.
For a 1m patch cable noise rejection, cross talk & similar length isn't really an issue.
Like it or not manufacturers get away with it because in the vast majority of situations a cat5 or even a failing cat5 has no real world consequence. It fails the standard yet still works in practice - on a physical level. Plus the network stack built on top of that has further fault tolerance.
If it's a long cable at the edge of tolerance or you're in a mission critical datacenter then yeah maybe worry about this stuff. Everyone else just grab a patch cable off amazon.
The specs define the ratings in terms of length though, don't they?
That suggests to me the tester takes the cable length as an input, and gives a valid rating for the length?
That suggests to me the tester takes the cable length as an input, and gives a valid rating for the length?
Cat-6, pah. Use barbed wire like a real sysop...
https://news.ycombinator.com/item?id=15910263
https://news.ycombinator.com/item?id=15910263
I wonder if Cat 7 cables are similarly bad. I would have thought that since you can visually verify that the pairs are all shielded, it would be harder to fake it.
Cat7 is in a weird spot. It's been rendered basically obsolete by 6a, which has performance that's almost as good and allows for full-distance 10gig. And while 7a was specified with the goal of supporting 40gig, it looks like 40gig is going to require cat8.
And you're not really supposed to put RJ45 plugs on cat7/7a either.
So while you can verify the foil is in there, it doesn't say all that much toward the total quality, since they're not quite a standard cable at all.
And you're not really supposed to put RJ45 plugs on cat7/7a either.
So while you can verify the foil is in there, it doesn't say all that much toward the total quality, since they're not quite a standard cable at all.
But isn't Cat7 better at shielding compared to Cat6a?
It has stricter requirements for the most part. But whether you're better off buying Cat7 with nonstandard plugs, vs. a model of Cat6a where they used shielded wires? I'm not sure.
On the other end of the spectrum (not testing specifications, but just simply "does it network?"), I have successfully ran a 100BASE-TX connection between industrial equipment using individual (not twisted) 24-AWG wires over 20ft.
Seeing what people have done with legacy phone wire sometimes is just disturbing.
When I was in high school, I helped my friend get cable TV back to his bedroom by patching it over a really long length of phone cord. Crappy picture, but it was better than nothing, and he didn't have to share the living room TV any longer (his older brother later ran proper coax).
now having flashbacks to dialup tech support in the late 1990s.
Thankfully I've lost the superpower of telling precisely what's wrong with your phone line and where and how many excess devices you've plugged into it just by listening to a connection noise.
Thankfully I've lost the superpower of telling precisely what's wrong with your phone line and where and how many excess devices you've plugged into it just by listening to a connection noise.
Semi-off-topic Q: Why did twisted pair cables become the standard for ethernet? Seems to me from a signal integrity standpoint that coaxial (yes, there was "thin" and "thick" ethernet back in the day) or twinax type cables would be much better? Were they originally cheaper than coax, or what is the reason?
Briefly, twisted pairs reduce noice and crosstalk.
IIRC coaxial was terrible back then. It was stiffer and hence harder to place around corners, and the connectors were harder to clip on. I don't know if those reasons were important or even considered, back then.
Cost and simplicity of installation. Twisted pairs and crimp-on RJ connectors were already widespread in telecom due to POTS. If not for anything else, they were cheap and their reliability well understood due to economies of scale.
On the other hand, coax cable was significantly more expensive per length. Compared to RJ, BNC coax connectors were expensive and hard to correctly crimp onto the cable. When computer industry tried to make them cheaper it also resulted in very crappy products.
Unreliable connections were cause of most of the gripe with older coax-based networks. Which is kind of counter intuitive. A properly made BNC is very reliable and still used extensively in electronics test equipment and RF applications. But apparently reliability just didn't scale down cost-wise.
On the other hand, coax cable was significantly more expensive per length. Compared to RJ, BNC coax connectors were expensive and hard to correctly crimp onto the cable. When computer industry tried to make them cheaper it also resulted in very crappy products.
Unreliable connections were cause of most of the gripe with older coax-based networks. Which is kind of counter intuitive. A properly made BNC is very reliable and still used extensively in electronics test equipment and RF applications. But apparently reliability just didn't scale down cost-wise.
I also don't miss the daisy-chain wiring of coax Ethernet. Any one connector getting out of whack, or a bad/missing terminator on either end, would take the whole network down.
Yes, but network topology is orthogonal to the type of cable used. We could have just as well used coax for modern switched connections.
We did star configure CCTV systems using RG59 and RG6. The cables are heavy and the connectors big. You can't get the same density as with UTP. A 48 port coax switch took 4U versus a 1U UTP switch
And adding a new drop with coax meant taking down the entire network temporarily.
In the 90s I worked for a small company whose LAN was Ethernet over coax. The main issue was if there was a dodgy BNC connector/splitter or break in the cable anywhere in the building, the whole LAN would go down, which was fun to track down. When hubs and switches became cheaper and twisted pair (10BASE-T) more common we migrated over.
Yeah, for ethernet the switch from coax to twisted pair coincided with the switch to a star topology. That topology change was good for a lot of reasons.
When asking this question, I was more interested in learning about the signaling issues in the different cable types.
When asking this question, I was more interested in learning about the signaling issues in the different cable types.
I just bought 1k feet of Cat 6 cable and ran it through my house two days ago. Would have been useful to know then.
Anyone willing to suggest a cable that meets cat 6?
Blue Jeans Cable (they wrote the article): https://www.amazon.com/Certified-Blue-Cable-Assembled-Jeans/...
Update: This link is to their Amazon store page: https://www.amazon.com/stores/node/9182265011 .
Update: This link is to their Amazon store page: https://www.amazon.com/stores/node/9182265011 .
I bought 2 of these at 75 feet for $16 CAD (each) and it's maintaining expected 10 Gigabit on my home network.
https://www.amazon.ca/gp/product/B00H41LYGM/
https://www.amazon.ca/gp/product/B00H41LYGM/
Does "maintaining 10 GBit" only confirm Cat6? I don't want to * on your recommendation, just want to be nit-picky about these things after such an article :)
I used to work work for a company involved in 10GE some years ago.
I believe maintaining would be no link drops, but would include fast-retrains, where the cable coefficients are quickly synced without losing link, resulting in some number of dropped packets around the event. Low signal-to-noise will result in a higher bit error rate and sporadically dropped packets.
Adding aggressors (noisy fluorescent tubes, power lines, RF transmitters, etc) would eat away at the margin. But, if you're doing short runs (like 30m), then you've got absolute loads of headroom, at least with the fairly standard equipment we were testing. And also, the bit error rate is for full speed. If you don't have constant 10G traffic, then your error rate will be proportionally lower since there will be a bunch of "idle" time.
When testing these, there's a bit error rate test performed at different lengths of cable. IEEE used to recommend something like 10^-13 (not sure if this has changed), but we would test, with some margin, at the full 100m using cables wrapped on spools (no external aggressors). We would also test with a "5 around 1" configuration, with 5 other fully active cables tied around the cable under test. If I recall correctly, this test required the full 10^-13. All of these cables were periodically verified to meet all specs.
But regarding cable quality, we would buy thousands of meters of cable without issues, from good vendors. You may have trouble finding compliant cable from China. If there was a problem, it was usually from someone bending and putting a permanent kink in the cable (causing a discontinuity in the impedance) or closing a door on it.
I believe maintaining would be no link drops, but would include fast-retrains, where the cable coefficients are quickly synced without losing link, resulting in some number of dropped packets around the event. Low signal-to-noise will result in a higher bit error rate and sporadically dropped packets.
Adding aggressors (noisy fluorescent tubes, power lines, RF transmitters, etc) would eat away at the margin. But, if you're doing short runs (like 30m), then you've got absolute loads of headroom, at least with the fairly standard equipment we were testing. And also, the bit error rate is for full speed. If you don't have constant 10G traffic, then your error rate will be proportionally lower since there will be a bunch of "idle" time.
When testing these, there's a bit error rate test performed at different lengths of cable. IEEE used to recommend something like 10^-13 (not sure if this has changed), but we would test, with some margin, at the full 100m using cables wrapped on spools (no external aggressors). We would also test with a "5 around 1" configuration, with 5 other fully active cables tied around the cable under test. If I recall correctly, this test required the full 10^-13. All of these cables were periodically verified to meet all specs.
But regarding cable quality, we would buy thousands of meters of cable without issues, from good vendors. You may have trouble finding compliant cable from China. If there was a problem, it was usually from someone bending and putting a permanent kink in the cable (causing a discontinuity in the impedance) or closing a door on it.
No worries. Be as picky as you want to be. I merely recommended the only cable I can actually recommend for the average consumer. Was sure to add for my home office for some context.
This cable fits the bill for running a connection between access points in my home. The speed is top notch, not seeing drops in speed for the many times I've moved large files across the network. Cabling seems sturdy and rugged, even while I was feeding it through various locations.
As long as it appears reliable and I get the speeds I expect, I don't really care much beyond that. It works, it was cheap, I don't ask many more questions.
Would this stuff hold up in a data center? Probably not. When I was wiring up homes or buildings, I always bought a high quality spool of Cat 6 from a trusted local provider.
They asked for a recommendation, I did a mental "what are they likely asking? As someone in their home, or as a data center IT worker hooking up racks of servers?"
I work remotely now, so I'm at home. Just assumed they were at home or similar. Maybe not the answer they were looking for. shrugs
This cable fits the bill for running a connection between access points in my home. The speed is top notch, not seeing drops in speed for the many times I've moved large files across the network. Cabling seems sturdy and rugged, even while I was feeding it through various locations.
As long as it appears reliable and I get the speeds I expect, I don't really care much beyond that. It works, it was cheap, I don't ask many more questions.
Would this stuff hold up in a data center? Probably not. When I was wiring up homes or buildings, I always bought a high quality spool of Cat 6 from a trusted local provider.
They asked for a recommendation, I did a mental "what are they likely asking? As someone in their home, or as a data center IT worker hooking up racks of servers?"
I work remotely now, so I'm at home. Just assumed they were at home or similar. Maybe not the answer they were looking for. shrugs
I would think the real test is to do some pulling on the cable to make sure it's reasonably sound structurally, and also maintaining 10 GBit at the spec maximum for cat-6... but really if it works for however long you run it, what does it matter
I'd argue that if you're not doing a home setup, you should use fiber for anything 10GBe+. Less latency and power draw.
DAC/Twinax if inside rack as it's much cheaper, lower latency and less power. Fiber between racks though.
ah yes, completely agree!
Can Fibre support PoE? As that's really useful at home.
I am curious what you are doing that is 10GB+ on your home network. Not snark. Genuinely curious.
I'm not using 10GB! I was not implying that. I am however using cat6 cables and I get around 800mbps speed around the house. I have PoE injector and some of my devices (access point, cameras, raspberrypies) are powered through the cable. I was genuinely wondering if one of the disadvantages of optical cables is the lack of PoE, due to the lack of copper wires.
Fiber is often chosen specifically for its electrical isolation properties (runs between different buildings as just one example).
Your intuition that fiber doesn't support PoE is correct.
Your intuition that fiber doesn't support PoE is correct.
One thing to watch out for is CCA cat cabling. It’s cheaper, because it’s copper coated aluminum. I have no clue if it reaches spec, but i don’t think it’s worth it because it would cost so much to rewire your house again later (or trace down an outage/packet loss in production).
I actually have CCA cabling. On purpose.
Why? It's cheaper. And I only had to run about ~15 meters through my small rental apartment. And it basically cut my cabling cost in half while having enough reserve cables left.
It hasn't failed on me so far. When I buy my own house, I will definitely switch to better cables. But in such a small rental apartment, which I won't be living in too long, I didn't find it worth my money to buy better cabling.
Why? It's cheaper. And I only had to run about ~15 meters through my small rental apartment. And it basically cut my cabling cost in half while having enough reserve cables left.
It hasn't failed on me so far. When I buy my own house, I will definitely switch to better cables. But in such a small rental apartment, which I won't be living in too long, I didn't find it worth my money to buy better cabling.
For our projects, we always sourced directly from big names in the industry like Nexans and LeGrand. With a hefty price, of course. But I always wondered whether their cables are worth the price. Of course, we have let our system integrators tested and reported diligently but yeah for big money, rigging is not so far fetched!
Is there any testing equipment that can test for compliance, and is inexpensive? Fluke cable tester (DTX-1800) that was mentioned cost $40,000! I saw an eBay listing for $6500 for used one. There are other cheap testers out there but they seem to be just continuity tester, and doesn't test for cross-talk, etc.
The IDEAL LanTEK III-500 is 5kish.
The cheapest test equipment is going to be some spare computer hardware at each end and a passing a test-suite of your expected performance numbers.
I'm going to be changing out the flooring of my condo at some point and am wondering if there's a decent solution for underfloor wiring that doesn't involve building a raised subfloor. Or perhaps I could build a very small one, I just wouldn't want to just wing it.
I did just that few months ago. I had an electrician come and make channel in the floor, lay in it some plastic tubing and later he pulled the cables through it.
I would love to see an Ethernet spec for >100m runs, perhaps at lower speeds. If I could do 1 Gbps at 150m on Cat 6A cable without egregiously exceeding the spec, it would be great.
As long as you meet the signal integrity standards, I don't think you majorly violate anything. So run one speed level slower than your cable normally supports and do some math on crosstalk per meter.
I'd be more worried about skew. CAT5e and 6a seem to have the same delay skew spec, and I can easily imagine Ethernet PHYs that are simply unable to operate beyond 100Mbps with out-of-spec skew.
CAT7 seems dubious (not recognized at all by everyone in the industry) but has a tighter delay skew spec, so this would help.
Another potential issue would be if the PHY has an equalizer that can handle reflections due to not-quite-perfect termination at 100m or closer but has trouble beyond 100m.
Something like a 1000BASE-T-LR or something that just means "1 Gbps over CAT [whatever is needed] if properly installed at lengths up to 200m" would be quite nice. Most likely a lot of equipment would meet that spec out-of-the-box.
CAT7 seems dubious (not recognized at all by everyone in the industry) but has a tighter delay skew spec, so this would help.
Another potential issue would be if the PHY has an equalizer that can handle reflections due to not-quite-perfect termination at 100m or closer but has trouble beyond 100m.
Something like a 1000BASE-T-LR or something that just means "1 Gbps over CAT [whatever is needed] if properly installed at lengths up to 200m" would be quite nice. Most likely a lot of equipment would meet that spec out-of-the-box.
Not sure whether this still holds for 1Gb and faster ethernet, but there used to be a maximum length due to collision detection.
An ethernet frame has a minimal length, and since the cable (used to be) a shared medium, frames could collide. Such a collision could be detected by senders whilst sending the frame, allowing for a re-send. However, when the cable is long enough, you could get collisions happen after you are finished sending.
I'm guessing that the newer standards that only allow point to point connections invalidate those requirements though.
An ethernet frame has a minimal length, and since the cable (used to be) a shared medium, frames could collide. Such a collision could be detected by senders whilst sending the frame, allowing for a re-send. However, when the cable is long enough, you could get collisions happen after you are finished sending.
I'm guessing that the newer standards that only allow point to point connections invalidate those requirements though.
That's not actually true. When the 100 meter limit was established, a minimum-length frame would be 10 kilometers long.
It's possible to link together two wifi APs by removing the antennas on both APs, and linking the antennas by SMA-coax cable.
I know this works for normal Wifi modes. Now I wonder if you could get this to work with MIMO. From my limited understanding, it should be possible if the cables have lengths that vary by about 5-15cm.
I know this works for normal Wifi modes. Now I wonder if you could get this to work with MIMO. From my limited understanding, it should be possible if the cables have lengths that vary by about 5-15cm.
Isn't this effectively how MoCA works?
From some preliminary reading it seems like MoCA uses a protocol different from WiFi, since it seems to operate between 1000 and 1500 MHz.
The protocol used is probably more efficient, since it doesn't have WiFi's problem of the signal following multiple paths.
The protocol used is probably more efficient, since it doesn't have WiFi's problem of the signal following multiple paths.
100m is not a hard limit, but just a maximum limit that Ethernet devices are guaranteed to work correctly. If you have good cables that are terminated correctly, you can actually exceed this limit.
But exactly how much you can push the limit would be an interesting experiment for another day.
But exactly how much you can push the limit would be an interesting experiment for another day.
Seems like the actual issue is that the specs are way too tight. If 80% of the cables fail the test but virtually all of them work fine in the real world, what does that say about the test?
How common is it for someone to buy one of the retail-grade cables they're discussing in this article, and find that it doesn't work reliably?
How common is it for someone to buy one of the retail-grade cables they're discussing in this article, and find that it doesn't work reliably?
It also is a testament to the ability of the interface vendors to get solid connections of out-of-spec cables. I have a small server room that is only wired with a 200+ foot run of in-wall Cat5e cables that the building was originally wired with. Running fiber to the room would be a multi-thousand-dollar job. On a lark, I took two switches with 10G-BASET interfaces and successfully brought up a 10Gigabit link across that Cat5e. I brought that link into production 6 months ago, and through that time have had less than 100 errors per link. Just incredible.
Thank you for testing out just how over-spec’d our world is.
I recall making a very crude crossover cable by cutting and soldering wires together and still got 100mbit (as high as I could test, this was early 2000s I think).
I recall making a very crude crossover cable by cutting and soldering wires together and still got 100mbit (as high as I could test, this was early 2000s I think).
You and the GP poster might both live in a nice little RF-shielded part of "our world", mind you. A Cat 6 cable, like a "ruggedized" laptop or a mars rover, will work near sources of EM interference that would knock your regular cable (or computer, or robot) over dead. That's most of why they cost more.
Though, mind you, right tool for the job—I'm surprised that everybody is talking about "getting perfect cables" for maximum interference-tolerance in business-critical applications, when what I'd expect the professionals here to be thinking in terms of is taking measurements of the local RF environment they're going to do cable runs in, and then using the cheapest thing that's within tolerance.
Though, mind you, right tool for the job—I'm surprised that everybody is talking about "getting perfect cables" for maximum interference-tolerance in business-critical applications, when what I'd expect the professionals here to be thinking in terms of is taking measurements of the local RF environment they're going to do cable runs in, and then using the cheapest thing that's within tolerance.
There is an old show floor demo I've heard about where a bunch of barb wire is used to transmit Ethernet data. The crucial part was spacing the wires apart to get the right impedance. Don't recall what speed them were transmitting though.
That goes back to the original demonstration of 10BaseT (10 Mbit). It blew everybody away, definitely one of the great Valley demos of all time.
I want to say this was Bob Metcalfe, but not 100% sure he was involved.
I want to say this was Bob Metcalfe, but not 100% sure he was involved.
The category specs are the 'requirements' for rock solid Ethernet at a certain distance in a bundle with mixed low voltage, not _too_ close to AC distribution, in reasonable RF conditions. Cat 6a goes to the full 100 meters (330 feet) at 10Gbps, Cat 6 goes to 55 meters (180 feet).
Most people buying retail cables aren't going to be using that for that distance, and are more likely to run at 1Gbps than 10Gbps; where cat5 (not e) meets the spec at full distance. I'm a bit surprised that the cables didn't all meet cat5 (e) spec, but even that is not really required to have a solid ethernet connection at 1Gbps if you're not in a tricky environment -- I ran a 1Gbps drop over mostly cat 5e with a ~ 20 foot section of cat 3 for many years with no apparent issues (repurposed a buried 4-pair pots drop to a separate structure for ethernet).
Most likely any reliability issue with this cables is going to be if the connectors were poorly crimped and the connections loosen over time. That said, ethernet negotiation is a slower protocol, that's easy to decode, so it's very possible for both link partners to negotiate to something the wiring can't sustain. I've seen some drivers end up negotiating down to a lower speed in this case, but it's not part of any formal ethernet spec AFAIK.
Most people buying retail cables aren't going to be using that for that distance, and are more likely to run at 1Gbps than 10Gbps; where cat5 (not e) meets the spec at full distance. I'm a bit surprised that the cables didn't all meet cat5 (e) spec, but even that is not really required to have a solid ethernet connection at 1Gbps if you're not in a tricky environment -- I ran a 1Gbps drop over mostly cat 5e with a ~ 20 foot section of cat 3 for many years with no apparent issues (repurposed a buried 4-pair pots drop to a separate structure for ethernet).
Most likely any reliability issue with this cables is going to be if the connectors were poorly crimped and the connections loosen over time. That said, ethernet negotiation is a slower protocol, that's easy to decode, so it's very possible for both link partners to negotiate to something the wiring can't sustain. I've seen some drivers end up negotiating down to a lower speed in this case, but it's not part of any formal ethernet spec AFAIK.
> I ran a 1Gbps drop over mostly cat 5e with a ~ 20 foot section of cat 3 for many years with no apparent issues (repurposed a buried 4-pair pots drop to a separate structure for ethernet).
Oh man that takes me back. I did the same thing though it was for 100Mpbs at the time. I distinctly remember staring at the twisted pairs prior to starting and wondering, “Is the actually going to work?”
Oh man that takes me back. I did the same thing though it was for 100Mpbs at the time. I distinctly remember staring at the twisted pairs prior to starting and wondering, “Is the actually going to work?”
Yeah, I wired it up, because I knew at least I could run it at 10baseT if I had to, and then I might as well try it at the fastest I could, and it worked ok at 1G, so that's what I used. :)
Is your claim that manufacturers should be allowed to sell products with complete fabrications on the label because most of the time it is "good enough"?
If manufacturers want to sell Cat 5E (or lower grade) cables they are free to do so, but the market won't accept the higher price they want to fetch for those cables.
It also means the manufacturers are either incompetent (doing no testing) or are knowingly testing the cables but not bothering to test them to the specification they are claiming on the package. Either way that's a crime.
If manufacturers want to sell Cat 5E (or lower grade) cables they are free to do so, but the market won't accept the higher price they want to fetch for those cables.
It also means the manufacturers are either incompetent (doing no testing) or are knowingly testing the cables but not bothering to test them to the specification they are claiming on the package. Either way that's a crime.
Is your claim that manufacturers should be allowed to sell products with complete fabrications on the label because most of the time it is "good enough"?
That certainly requires a creative reading of what I wrote. No, I'm saying that the test specs may be rigged to favor high-end cable manufacturers, and we may all be paying too much for cables as a result.
That certainly requires a creative reading of what I wrote. No, I'm saying that the test specs may be rigged to favor high-end cable manufacturers, and we may all be paying too much for cables as a result.
The cable tester they are using is setup to test the actual specification.
That is to say they are testing the _very definition_ of Cat-5E, Cat-6, or Cat-6A. That's the thing about cabling standards: either you meet the requirements of the standard or you don't. I presume the committee that designed 100Base-T, 1000Base-T, and 10GBase-T didn't pick numbers out of nowhere for no reason.
Your comment seemed to be using circular reasoning... if the standard is too stringent than it's just a free-for-all, or the manufacturer's made-up non-standard, but there is only one way to be Cat-6A: follow the specs laid out in the standard. Otherwise why even have standards?
That is to say they are testing the _very definition_ of Cat-5E, Cat-6, or Cat-6A. That's the thing about cabling standards: either you meet the requirements of the standard or you don't. I presume the committee that designed 100Base-T, 1000Base-T, and 10GBase-T didn't pick numbers out of nowhere for no reason.
Your comment seemed to be using circular reasoning... if the standard is too stringent than it's just a free-for-all, or the manufacturer's made-up non-standard, but there is only one way to be Cat-6A: follow the specs laid out in the standard. Otherwise why even have standards?
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Just because its meat, doesn't mean you can sell me horse flank as usda filet. The differince is critical is some applications, even if overspec'd in others. Thats the point of having a standard. If you only need cat5e quality, you can just buy that, at signifigant discount.
Similar to buying organic food, or ocean caught fish vs. farm raised.
Change the label, double the price. The temptation is very strong.
Similar amusement from the Capacitor Plague: https://en.wikipedia.org/wiki/Capacitor_plague
Change the label, double the price. The temptation is very strong.
Similar amusement from the Capacitor Plague: https://en.wikipedia.org/wiki/Capacitor_plague
For what it's worth, I just bought a few one-off Ethernet cables at Fry's, and while I didn't look all that hard, I didn't see any that weren't marketed as Cat6.
More specifically, for a digital signal, what does "working, but not up to spec" look like? Occasional packet loss? Corrupted data that is masked by ECC?
Can also mean: Works with devices A and B, stops working with devices A and C.
"working, but not up to spec" can mean "works today, stops working tomorrow when subjected to a bit more nearby electrical noise". 10GbaseT links frequently can't negotiate down, so your link can just stop working whenever.
Anything "masked" by ECC is part of the design.
Most real cable runs have large margin because they're shorter than 100m.
If they "worked fine" they would be meeting the spec they said they would.
I don't know about you, but I plug my cables into hubs and NICs, not TDRs and oscilloscopes.
Absolutely nothing in the real world needs twisted-pair cables to exhibit 54 dB of NEXT. If it does, that's an engineering failure in itself, IMO.
Absolutely nothing in the real world needs twisted-pair cables to exhibit 54 dB of NEXT. If it does, that's an engineering failure in itself, IMO.
The LAN on the International Space Station, maybe?
All that said, the article does manage to skim over a few things it should have talked about. There are actual physical differences between the cabling specs which are a result of the 6A signalling requirements. The termination is _MUCH_ stricter and likely the cause of 99% of the failures in cases where the cables actually are 23AWG, properly twisted and isolated. Its these latter three things which will allow you to identify "real" cat6A rather than the stuff being relabeled by cable manufactures claiming to have found some secret method of making what are basically cat5E cables 6A.
(back to my 5e comment. The thing to keep in mind about a lot of this is that the standards specify minimums. The whole cat5E grouping was one where there was a race to out-specify everyone else, which is why you can find cat 5E 500Mhz labeled cabling, although most places just renamed it to cat 6 and charged a few cents more per foot. The other thing to keep in mind is that these specifications end up being given in loss/crosstalk per foot, so its quite possible to run higher data speeds on short cables that are non compliant per foot, particularly if they are terminated properly. Hence other comments I've made on this site about running 10GbaseT in my house on cat5E without any apparent signally/packet loss due to the runs all being very short.).