Patch cable question

[alan_m]

Isn't there already problems in a office environment with contention?

[SteveW]

Wireless is getting very fast, but wired is getting faster too (2.5G is getting reasonably common and 10G is available) and, more importantly, wired allows full bandwidth per device, whereas wireless shares it between numerous devices and can suffer from interference from neighbours too. Probably not that much of a problem for many, but maybe for someone editing large files directly to and from the storage on their home server, while their satellite boxes were recording multiple channels to networked storage, their wife was watching streamed UHD video and all three kids were playing online games, over a shared wifi band.

[The Natural Philosopher]

One of my hospitals has at leats 15 wifi nodes visible on a scanner . Shannon tells us that maximum bit rate is bandwidth times signal to noise. When you are essentially not using dish aerials you are broadcasting power to every place it *might* be needed. Down a cable you only transmit the power needed at the far end. And your bit rate tends to be more limited by propagation delay than power or noise. At least with Ethernet protocols.

A cable will always be higher bit rate, lower power and 100 times more secure than wifi. If those are not problems for you, use wifi.

[SteveW]

In my experience, most offices only use wifi for visitors and where mobile phones can't get a signal, with the company's own computers using wired networks.

In my current and previous offices, we plug(ged) our laptops into small boxes with USB-C and those boxes power the laptop and connect mouse, keyboard, two monitors and wired ethernet.

[The Natural Philosopher]

Wireless is convenient for portable devices. Or where there is no easy Ethernet. But all my fixed kit is wired for reliability. Expect a couple of Pi zeros running low bandwith and tucked in places where Ethernet would be a pain to run.

Obviously phones and laptops use wifi.

I don't need blazing speeds, but I do need relaibility.

[RJH]

Inclined to agree. I've just moved from an ethernet NAS linked house to the current mesh-wireless. It's not as quick and reliable, but easily good enough for chucking the odd GB file around, TV streaming etc.

And it's getting to the point where I'd happily trade fibre broadband for a 5G unlimited mobile tariff. Again, not as good, but good enough.

[Pancho]

Shannon, Shannon? Where have I heard that before?? Oh!, yes, I remember it was when they were telling us that our phone modems would never break the 34Kbs theoretical barrier.

You can come up with yeahbut, nobut, that isn't what it meant, they found a way to use the phone lines differently. But this also applies to your objections to WiFi. There are different ways of doing things.

I hear we already have home access points with directional beam-forming, to overcome one of your objections.

A very bold statement, given the speed I see from my crappy mobile phone. I think in my home LAN they could do faster. I think RJH summed it up: wired, or fibre, is better, but we only need good enough. We don't need infinite bandwidth, WiFi is very close to delivering all that we need.

[John Rumm]

A normal CAT5E (decent quality all copper[1] fully wired) patch lead will work just fine. There will not be any advantage to using a higher spec cable, it will just be more expensive and harder to route / dress nicely since it will be stiffer and require a larger bend radius.

[1] Avoid ones that are CCA (Copper Clad Aluminium) or CCS (Copper Clad Steel)

A connection to a network switch (i.e. that built into the router) and a PC requires a normal "straight through" wired lead.

(There was a time that you might need a "crossover" cable when connecting one PC directly to another without a switch or hub between them, but most modern Ethernet kit will automatically configure as required, making crossover cables mostly redundant).

[John Rumm]

A patch lead is typically an Ethernet cable built using a RJ45 at each end and using more flexible stranded wires in the cable.

An "Ethernet cable" is a more generic term, and could include patch leads as well as the typical solid core CAT cables used for building wiring. It could even include archaic cables like 50 Ohm Co-Ax as was once used for 10 Mbps Ethernet

[John Rumm]

Short of really cheaping out and buying a 4 wire patch lead, you would be hard pushed to find something that does not support 1 gig.

[John Rumm]

Actually predicts the maximum throughput achievable with a 3kHz bandwidth channel in the presence of noise. Modems using the audio channel in both directions with normal SNR levels never exceeded its predictions.

56k modems "circumvented" the limitation in one direction by keeping the signal mostly digital for the bulk of the path, and doing one final D to A conversion at the last minute. This improved the overall SNR in one direction. The result still being in line with what the Shannon channel capacity predicts for the line with a better SNR).

There are, and wifi has improved immeasurably. However it is still a broadcast technology, and its performance will vary based on a whole host of parameters that you have little or no control over.

Yup, a standard part of WiFi 6 (aka 802.11ax)

Gb+ over wifi is certainly doable. In fact WiFi 5 (802.11ac) has shown real world speeds over 1 Gbps in real world applications. 802.11ax will do better (2x) than that in the right circumstances.

Speed wise it can be good enough, but there is more to consider than speed.

[John Rumm]

Not necessarily the case with the latest kit which uses multiple antennas in a phased array configuration. That allows directional beam forming for links with client devices.

This makes more effective use of spectrum and transmit power in congested (RF) spaces.

[The Natural Philosopher]

As I said, if reliability, power effciency, security and speed are not an issue for you, use Wifi.

The lazy man's networking...

[Andrew]

No. Installed cat5e normally has solid cores, while patch cables ?should have multi-stranded cores.

If you fitting your own connectors, I believe there are different crimp types for solid or stranded.

If you are just buying a 10 mtr patch cable and not bothering with a 'proper' installation with a cat5e wall box at each end (so 2 short patch cables needed) then you don't need to be aware of the difference.

[Chris Green]

Yes, and I've never found an easy way to work out which is which!

[The Natural Philosopher]

+1

And, worse still, several different makes of connectors that need different tools to work. Back in the day when patch cables cost a fiver each we made our own. Not any more.

+2 House wiring is solid core. flex cable is used where it needs to flex!

[Joe]

My netbook can see 12-16 from my house, though most are too low to be of use, and my mobile phone can only see three or four of them.

Things have improved. I was asked to connect about 8 PCs in a new office by wifi about twenty years ago. I gave up after about two weeks, there was no possible way to keep that many links working continuously. It was a low-rise office park, only three other companies in the same building, and two other similar buildings fifty metres or so apart. What was odd was that I couldn't see obvious interference sources, the company actually had a portable spectrum analyser.

After two weeks I started pulling up floor tiles and taping bits of curtain rod together...

[Rod Speed]

But there is no good reason for that.

[Rod Speed]

But wifi works fine for everything in your house except for some exceptional circumstances.

[NY]

I have used standard unbranded Cat 5 or Cat 6 flat cable that is 15 m long. I've have data transfer speeds of around 300 Mbit/sec between a Windows PC and an Raspberry Pi at opposite ends of the cable, measured for a SAMBA \\server\sharename\file.ts file copy of a large (eg 1 GB) file. That's for Ethernet adaptors which claim to be 1 Gbps.

A raw transfer, without also testing access to an HDD that is connected by USB to the Pi, would probably be even faster.

Flat cable has the big advantage over circular cross-section that it can be tucked between the edge of a carpet and a skirting board, under the metal strip in a doorway that divides one room;s carpet from another or even under the carpet, especially near the gripper rod where it's unlikely to get walked on.