6 ms·

It would be nice if this article defined a "ethernet patch cable". I think he's just using "patch" as a slang term for a short cable and it actually works with

by nkurz 17d ago

It would be nice if this article defined a "ethernet patch cable". I think he's just using "patch" as a slang term for a short cable and it actually works with any length of standard cable, but I'm not certain. Traditionally (pre-2000?), one had to use a special "crossover cable" to do direct connections like this, but apparently modern Gigabit ethernet adapters are able to detect this situation automatically?

bronlund 17d ago
The way I learned this, is that patch cables use stranded wires, but ethernet cables use solid wires.
- globular-toast 17d ago
  They are all just twisted pair cables, probably Cat5e or Cat6 etc. The solid ones are usually used for structured cabling, inside walls and trunking, that doesn't often move. Structured cabling is terminated into keystones or patch panels, the "female" end. Patch cables are outside of walls and designed to be moved around and plugged and replugged. They are terminated with 8p8c "male" connectors, commonly called rj45. Stranded cable is used because it's much more flexible.
  - TorKlingberg 15d ago
    This is the same for mains power cables. Permanent installs are usually solid cores, while the "flexi" cables you plug into a socket are stranded.
    - globular-toast 14d ago
      Yep, up to a certain point. Thicker wires like 6mm^2 are stranded again, but the strands are very thick and few.
lstodd 17d ago
IIRC crossovers are pre-2000, yes. "Fast Ethernet" or 100Base-T adapters usually could talk over straight link. edit: as for length, it depends. you won't get a gigabit over 150m of crap cat3, but you will get a link, even if it's 10 half-duplex.
rmunn 17d ago
https://en.wikipedia.org/wiki/Medium-dependent_interface#Automatic_MDI-X https://en.wikipedia.org/wiki/Medium-dependent_interface#Aut... is what allowed the switchover to happen automatically, and it got folded into the 1000BASE-T standard. So yes, crossover cables are no longer required because the two Ethernet adapters at either end can negotiate between them to have one of them "flip" the meaning of its Receive (RX) and Transmit (TX) pins.
facepalmz 17d ago
[flagged]
- steve1977 17d ago
  No, traditionally a patch cable is a cable that you would use in a networking rack to connect (to "patch") from say a network switch to the desk outlets or to another switch. A patch cable would explicitly be NOT a crossover. The main difference between patch and "normal" is that the former is using stranded conductors and the latter solid conductors. That makes the patch cable more flexible (physically)
  - justsomehnguy 17d ago
    I have a feeling this is some re-invention of the definitions happening. It's just a holdover from the telephone networks, where you used a short cable to actually phsyically connect - patch[0] - two lines. Therefore - patch-panel and patch-cord or patch-cable. https://www.merriam-webster.com/dictionary/patch https://www.merriam-webster.com/dictionary/patch
  - ButlerianJihad 17d ago
    I am not sure that I know of any Ethernet (IEEE 802.3) standard cabling which uses solid-core wires rather than twisted-pair stranded wires. I can understand and see that many people consider "structured cabling" to consist of the former, but this article does not seem to mandate that construction, and indeed includes many types of twisted-pair and "patch" cables in the list of acceptable "structured cabling solutions." https://en.wikipedia.org/wiki/Structured_cabling https://en.wikipedia.org/wiki/Structured_cabling So I believe that, in the realm of Ethernet in particular, "patch" vs. "structured" is not a useful distinction.
    - globular-toast 17d ago
      Yeah, it's not patch vs structured. Patch cables are part of structured cabling. But you won't generally find solid core wires outside of structured cabling, because they are inflexible, unwieldly and in many cases can't even be terminated with RJ45 plugs anyway (they are often too thick). To regular people it's probably enough just to say Ethernet cable. Outside of structured cabling you don't really need to care and probably don't have a choice anyway. If someone says patch cable they probably know a bit about structured cabling and couldn't help themselves. Within structured cabling the rabbit hole is quite deep. Even within a single standard like Cat6 there are many possible cable constructions with different types of shielding and wire gauge etc. It becomes important when you need the network to certify as Cat6 and support PoE in a high noise industrial environment, for example. And, of course, Ethernet can run over other cable types anyway, like fibre.
pezezin 17d ago
Gigabit Ethernet doesn't need to detect anything because it sends and receive over the 4 pairs simultaneously using echo cancellation.
dboreham 16d ago
Seriously people? HN doesn't know what a patch cable is??
- nkurz 16d ago
  There doesn't seem to be agreement as to exactly what one is, with several definitions already appearing in the comments here. Do you agree with one of them and think everyone else is wrong? Or do you have yet another standard definition that we should all be using? My problem with the article was that "patch" doesn't seem to add any useful information. Unless he was using a restrictive definition intending to exclude things like crossover cables (which still work), he could have just as well said "transfer files over a blue Ethernet cable" with equal precision. If he meant to say that at this point in time "you can use _any_ ethernet cable to transfer files directly between two computers", I think it would have been better to say that rather than appearing to add a restriction on the type of cable required.
- dang 16d ago
  "Please don't sneer, including at the rest of the community." It's reliably a marker of bad comments and worse threads. https://news.ycombinator.com/newsguidelines.html https://news.ycombinator.com/newsguidelines.html (More at https://news.ycombinator.com/item?id=49512349 https://news.ycombinator.com/item?id=49512349)

by nkurz 17d ago

bronlund 17d ago

The way I learned this, is that patch cables use stranded wires, but ethernet cables use solid wires.

globular-toast 17d ago
They are all just twisted pair cables, probably Cat5e or Cat6 etc. The solid ones are usually used for structured cabling, inside walls and trunking, that doesn't often move. Structured cabling is terminated into keystones or patch panels, the "female" end. Patch cables are outside of walls and designed to be moved around and plugged and replugged. They are terminated with 8p8c "male" connectors, commonly called rj45. Stranded cable is used because it's much more flexible.
- TorKlingberg 15d ago
  This is the same for mains power cables. Permanent installs are usually solid cores, while the "flexi" cables you plug into a socket are stranded.
  - globular-toast 14d ago
    Yep, up to a certain point. Thicker wires like 6mm^2 are stranded again, but the strands are very thick and few.

lstodd 17d ago

IIRC crossovers are pre-2000, yes. "Fast Ethernet" or 100Base-T adapters usually could talk over straight link. edit: as for length, it depends. you won't get a gigabit over 150m of crap cat3, but you will get a link, even if it's 10 half-duplex.

rmunn 17d ago

https://en.wikipedia.org/wiki/Medium-dependent_interface#Automatic_MDI-X https://en.wikipedia.org/wiki/Medium-dependent_interface#Aut... is what allowed the switchover to happen automatically, and it got folded into the 1000BASE-T standard. So yes, crossover cables are no longer required because the two Ethernet adapters at either end can negotiate between them to have one of them "flip" the meaning of its Receive (RX) and Transmit (TX) pins.

facepalmz 17d ago

[flagged]

steve1977 17d ago
No, traditionally a patch cable is a cable that you would use in a networking rack to connect (to "patch") from say a network switch to the desk outlets or to another switch. A patch cable would explicitly be NOT a crossover. The main difference between patch and "normal" is that the former is using stranded conductors and the latter solid conductors. That makes the patch cable more flexible (physically)
- justsomehnguy 17d ago
  I have a feeling this is some re-invention of the definitions happening. It's just a holdover from the telephone networks, where you used a short cable to actually phsyically connect - patch[0] - two lines. Therefore - patch-panel and patch-cord or patch-cable. https://www.merriam-webster.com/dictionary/patch https://www.merriam-webster.com/dictionary/patch
- ButlerianJihad 17d ago
  I am not sure that I know of any Ethernet (IEEE 802.3) standard cabling which uses solid-core wires rather than twisted-pair stranded wires. I can understand and see that many people consider "structured cabling" to consist of the former, but this article does not seem to mandate that construction, and indeed includes many types of twisted-pair and "patch" cables in the list of acceptable "structured cabling solutions." https://en.wikipedia.org/wiki/Structured_cabling https://en.wikipedia.org/wiki/Structured_cabling So I believe that, in the realm of Ethernet in particular, "patch" vs. "structured" is not a useful distinction.
  - globular-toast 17d ago
    Yeah, it's not patch vs structured. Patch cables are part of structured cabling. But you won't generally find solid core wires outside of structured cabling, because they are inflexible, unwieldly and in many cases can't even be terminated with RJ45 plugs anyway (they are often too thick). To regular people it's probably enough just to say Ethernet cable. Outside of structured cabling you don't really need to care and probably don't have a choice anyway. If someone says patch cable they probably know a bit about structured cabling and couldn't help themselves. Within structured cabling the rabbit hole is quite deep. Even within a single standard like Cat6 there are many possible cable constructions with different types of shielding and wire gauge etc. It becomes important when you need the network to certify as Cat6 and support PoE in a high noise industrial environment, for example. And, of course, Ethernet can run over other cable types anyway, like fibre.

pezezin 17d ago

Gigabit Ethernet doesn't need to detect anything because it sends and receive over the 4 pairs simultaneously using echo cancellation.

dboreham 16d ago

Seriously people? HN doesn't know what a patch cable is??

nkurz 16d ago
There doesn't seem to be agreement as to exactly what one is, with several definitions already appearing in the comments here. Do you agree with one of them and think everyone else is wrong? Or do you have yet another standard definition that we should all be using? My problem with the article was that "patch" doesn't seem to add any useful information. Unless he was using a restrictive definition intending to exclude things like crossover cables (which still work), he could have just as well said "transfer files over a blue Ethernet cable" with equal precision. If he meant to say that at this point in time "you can use _any_ ethernet cable to transfer files directly between two computers", I think it would have been better to say that rather than appearing to add a restriction on the type of cable required.
dang 16d ago
"Please don't sneer, including at the rest of the community." It's reliably a marker of bad comments and worse threads. https://news.ycombinator.com/newsguidelines.html https://news.ycombinator.com/newsguidelines.html (More at https://news.ycombinator.com/item?id=49512349 https://news.ycombinator.com/item?id=49512349)