Is Your Cat 6 Cable a Dog? (2013)
bluejeanscable.com
bluejeanscable.com
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.).
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 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 £100Maybe 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.
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.
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.
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.
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.
The Cat5E run is nearly perfect, entirely away from power lines, and clean direct from one room to another.
So if your cable run is "port->long solid conductor cable->port" its going to give you some extra feet.
But yes, previously there wasn't much point to it. Cat 5e is good enough for 1GbE, and for 10GbE you need Cat 6A.
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...
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.
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".
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.
That suggests to me the tester takes the cable length as an input, and gives a valid rating for the length?
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.
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.
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.
When asking this question, I was more interested in learning about the signaling issues in the different cable types.
Update: This link is to their Amazon store page: https://www.amazon.com/stores/node/9182265011 .
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.
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
Your intuition that fiber doesn't support PoE is correct.
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.
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.
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.
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.
The protocol used is probably more efficient, since it doesn't have WiFi's problem of the signal following multiple paths.
But exactly how much you can push the limit would be an interesting experiment for another day.
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?
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 want to say this was Bob Metcalfe, but not 100% sure he was involved.
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.
Change the label, double the price. The temptation is very strong.
Similar amusement from the Capacitor Plague: https://en.wikipedia.org/wiki/Capacitor_plague
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.
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.
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?”
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.
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 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?