For most fiber optic applications single mode and multi mode fiber optic cable made of glass is most suitable. Single mode and multi mode are the two transmission methods for fiber optics- having to do with how they get the signal to the other end of the glass. They are not interchangeable, so it’s important to know which you have. Single-mode fibers provide a single pathway for light to travel and are defined by their small core size of approximately 8.3 µm. Multimode fibers, on the other hand, have various paths, or modes, in which light can travel through optical fiber. These core sizes are larger, ranging from 50 µm to 62.5 µm.

Single Mode Fiber Optic Cable
Core Diameter: Approximately 8-10 micrometers.
Light Propagation: Uses a single light path (mode) to transmit data.
Wavelengths: Typically operates at 1310 nm and 1550 nm.
Distance: Ideal for long-distance communication (up to 100 km or more).
Bandwidth: Higher bandwidth and lower attenuation, providing high data transfer rates over long distances.
Applications: Long-haul telecommunications, cable television, and Internet backbones.

Multi Mode Fiber Optic Cable
Core Diameter: Approximately 50-62.5 micrometers.
Light Propagation: Uses multiple light paths (modes) to transmit data.
Wavelengths: Typically operates at 850 nm and 1300 nm.
Distance: Suitable for shorter distances (up to 2 km for slower speeds and up to 550 meters for high-speed networks).
Bandwidth: Lower bandwidth compared to single mode, with higher attenuation over long distances.
Applications: Local area networks (LANs), data centers, and intra-building networks.

Single mode fiber has very thin center core. You need a laser source that is very accurately shooting signal to it and all cable splices need to be very accurate. In typical telecommunications fiber, single mode operation is obtained with core diameters of 2–10 microns with a standard outer diameter of 125 microns. Once you get signal to single mode fiber, it will go through it with very little loss and other signal quality issues. Single-mode fibre are used almost universally in telecommunications over 1 km or so and are generally used at the 1300 nm and 1550 nm wavelengths. (Below 1100 nm, the Rayleigh-scattering dominates, while above 1600 nm the infrared absorption dominates). Single-mode fibers used in telecommunications typically operate at 1310 or 1550 nm and require laser sources (that some were expensive and many are still are expensive). OS1 and OS2 are standard single-mode optical fiber used with wavelengths 1310 nm and 1550 nm (size 9/125 μm) with a maximum attenuation of 1 dB/km (OS1) and 0.4 dB/km (OS2). Single-mode fibres are capable of wide bandwidths (e.g. >40 GHz) and are, therefore, ideally suited for long-haul and high capacity circuits.

Multimode fiber has core diameters considerably larger, typically 50, 62.5, 85, and 110 microns, again with a cladded diameter of 125 microns. Because of their larger core size, multi-mode fibers have higher numerical apertures which means they are better at collecting light than single-mode fibers. Multi mode fiber has thicker core, so sending light to it is easier (cheaper led technology will work and does not necessarily need laser transmitter). Multi-mode fiber has higher “light-gathering” capacity than single-mode optical fiber. In practical terms, the larger core size simplifies connections and also allows the use of lower-cost electronics such as light-emitting diodes (LEDs) and vertical-cavity surface-emitting lasers (VCSELs) which operate at the 850 nm and 1300 nm wavelength. Also cable splices do not need to be micrometer accurate to work OK. Multi mode is easier to work with and hardware for it is cheaper. As the name implies, multimode fibres are capable of propagating more than one mode at a time and they are ideally sited for high bandwidth (i.e. a few GHz) and medium haul applications. The disadvantages are much higher signal loss and more signal distortion – meaning supports less distance and less data bandwidth compared to single mode. Multimode fibers tend to have higher attenuation than single-mode fibers since the intrinsic loss of the multimode fiber is higher due to the natural loss of the fiber in the operating wavelengths of 850 nm and 1300 nm. The LED light sources sometimes used with multi-mode fiber produce a range of wavelengths and these each propagate at different speeds, which limits the available bandwidth over distance.

When transporting data over fiber optic cable, the transceivers have to match the cable type used. This means that the connector type in the transceiver and fiber optic type need to match. LC is the connector type tat is pretty common to find those when using SFP’s in network gear. Other connectors you may run into would be LC, SC, ST, and FC.

You need to select the transceivers that are designed to work with fiber type you have. Generally if you try to use multi mode transceivers with single mode cable, it will not work. Also trying to use single mode transceivers with multi mode cable does not give good results or work at all. Mixing different cable types on one fiber optic link is a recipe for a disaster.

Jacket color is sometimes used to distinguish multi-mode cables from single-mode, but it cannot always be relied upon to distinguish types of cable. The standard TIA-598C recommends, for civilian applications, the use of a yellow jacket for single-mode fiber, and orange for 50/125 µm (OM2) and 62.5/125 µm (OM1) multi-mode fiber.[3] Aqua is recommended for 50/125 µm “laser optimized” OM3 fiber.

Can you mix and match single mode and multi mode components / fiber? In some rare cases yes.

There are some special adapters that allow some mixing:
“The mode conditioning cables have allowed us to succesfully run Gb ehternet over our multimode cable using Single mode transcievers, but only at distances that would have worked using multimode transcievers. It did not work where we were exceeding the distance spec for multimode, must have been too much loss in the cable…”
“we just successfully ran from a SM Finisar FTLF1323P1BTR over a 400’ run of MM fiber to a media converter and it worked. I was trying to research this at this site so I posted our results.”
“I’m using 1000Base-LX/LH singlemode transceivers over 62.5 multimode fiber in several places, including a link over 1000’ long between two buildings. I do use mode-conditioning patch cables.”
Mode Conditioning Cable Selector: Launching a single-mode laser into the center of a multimode fiber can cause multiple signals to be generated that confuse the receiver at the other end of the fiber. A mode conditioning patch cord eliminates these multiple signals by allowing the single-mode launch to be offset away from the center of a multimode fiber. This offset point creates a launch that is similar to typical multimode LED launches. “The launch of the light coming out of the equipment begins on a Singlemode fiber. The Singlemode fiber is precision fusion spliced to the multimode fiber to a precise core alignment”

In a research laboratory environment I have run setup where a single mode transmitter sense signal to single or multi mode cable, and the signal was received with multi mode receiver. Also setup where single mode transmitter, single mode fiber, multimode fiber and multimode receiver has worked. Generally the direction that light goes from single mode to multi mode cable works somewhat OK, while the direction from multi mode to single mode causes a very high attenuation.

This article provides an overview of the most promising network technologies and innovations, such as time-sensitive networking, and looks at how they’re revolutionizing industrial communications.

Here are some links to some other related articles:

https://www.electronicdesign.com/blogs/altembedded/article/21240842/electronic-design-the-evolution-of-ethernet

Time for Time-Sensitive Networking (TSN)
Synchronization of clocks across the network is being standardized
https://www.electronicdesign.com/magazine/51099?utm_source=EG+ED+Auto+Electronics&utm_medium=email&utm_campaign=CPS220627006&o_eid=7211D2691390C9R&rdx.ident%5Bpull%5D=omeda%7C7211D2691390C9R&oly_enc_id=7211D2691390C9R

https://www.electronicdesign.com/industrial-automation/article/21241056/electronic-design-nxp-upgrades-industrialgrade-mcu-with-tsn-ethernet

https://www.electronicdesign.com/industrial-automation/article/21154669/electronic-design-switch-chips-bring-timesensitive-networking-to-factory-floors

What’s the Difference: Serial Communications 101
June 1, 2021
Communication is the hallmark of IoT and computer systems in general. Here are some of the basics.
https://www.electronicdesign.com/technologies/communications/whitepaper/21127800/whats-the-difference-serial-communications-101?utm_source=EG+ED+Auto+Electronics&utm_medium=email&utm_campaign=CPS220627012&o_eid=7211D2691390C9R&rdx.ident%5Bpull%5D=omeda%7C7211D2691390C9R&oly_enc_id=7211D2691390C9R

What is the bandwidth of your snax? How fast is your internet in bananas?
It is a common way to measure and MEME almost anything with a banana scale. There is now a banana scale for Internet speed: bananas transmit at about 53mbps on vdsl btw. VDSL over Banana is real – the tester got 53680/12658 kbps connection speed on a short run from in-house exchange/DSLAM, through banana, to a VDSL2 modem.
Here is a tweet from https://twitter.com/lauriewired/status/1735348312684020069 (also tweted at https://twitter.com/Evil_Mog/status/1709671970957386230)

It’s official, ADSL works over wet string Engineers at a small British internet service provider have successfully made a broadband connection work over 2m (6ft 7in) of wet string. The connection reached speeds of 3.5 Mbps (megabits per second). ADSL itself is something of an ingenious hack, carrying data over decades-old telephone wires designed only for voice. Some employees of Andrews & Arnold (a UK network provider) applied this mentality towards connecting their ADSL test equipment to some unlikely materials. The verdict of experiment: yes, ADSL works over wet string.

Here is picture of the experiment from https://www.revk.uk/2017/12/its-official-adsl-works-over-wet-string.html article.

According to those experiments it seems that you can use anything that is electrically conductive to transmit data signals in a way or another. In other news, materials that conduct electricity can be used to transmit signal. Marvelous finding lads!

Could you do that even without strings attached?
Can You Send The Internet Through Water Instead of Cables? The Literal Web Streaming Experiment!
https://www.youtube.com/watch?v=nEg9R7kcrIo

A lot of data goes through water, but using fiber optic cables instead of using the water itself as medium. There is a lot of data going under the sea. What’s more, 98% of the world’s internet cables are located undersea. This includes around 400 underwater cables around the world.

How The Internet Travels Under Sea
https://www.youtube.com/watch?v=LEM_I3HbIU8

How about telecommunications or fast data over barbed wire? Yes this has been done also.

Barbed wire fences were an early DIY telephone network. In some early years of telecommunication, even over 100 years ago, fences became phones: The unexpected use of barbed wire. A party line (multiparty line, shared service line, party wire) is a local loop telephone circuit that is shared by multiple telephone service subscribers. Party line systems were widely used to provide telephone service, starting with the first commercial switchboards in 1878. Barbed wire telephone lines were local networks created in rural America around the turn of the 20th century. In some isolated farming communities, it was not cost-effective for corporations to invest in the telephone infrastructure. Instead, the existing extent of barbed wire fences could be used to transmit electric signals and connect telephones in neighboring farms. Nowadays VDSL can be done over a farm fence if you want internet access or a security camera somewhere inconvenient.

But can you run Ethernet over barbed wire? In 1995 Broadcom showed it’s implementation of a subset of Fast Ethernet called 100BASE-T4 (different from the 100BASE-TX version that ultimately prevailed in the market). The value of the Broadcom T4 design was its ability to work at high speeds on horrible cables, so Broadcom wanted to demonstrate its operation using the world’s worst cable.

At Interop that year, Broadcom set up a 2×4-ft glass case containing eight parallel strands of barbed wire configured as four differential pairs, each running straight from side to side, suspended in air. The wires were ugly and rusty and had nasty little barbs all over them. A transmitter and a reel of Category 3 data cabling were on one side of the case. The data cabling led to the glass case where it coupled onto the four barbed-wire pairs. The other side of the case coupled through more Category 3 cabling to a receiver. They showed that 100 Mbit/s Ethernet can run over this kind of poor looking wiring sing their technology. During the show, lo and behold, Broadcom’s demonstration flawlessly conveyed 100 Mbps of data through the barbed wire. “Buy our parts” was the message the Broadcom marketing folks wanted to impress on their audience. There was also a display of this in action at COMDEX in Vegas (2000).

In year 2002 WideBand Gigabit Ethernet Over Barbed Wire was on display. WideBand Corporation has been showing its Gigabit Ethernet Without Rewiring by using barbed wire to make the point at trade shows from coast to coast this spring. WideBand has used its barbed wire demo as a way to underscore the robust transmission capability of its Ethernet products.

So how is it possible to use this kind of poor looking wiring for high speed data?
Only four properties really affect the performance of most digital transmission structures. The “big four” transmission-line properties are impedance, delay, high-frequency loss, and crosstalk. Crosstalk in a barbed-wire configuration is controlled by enforcing a large spacing between the pairs. The T4 system divides its data among the four pairs, so that each pair operates at only 25 Mbps. At that low frequency the skin-effect resistance of 4 ft of barbed wire is insignificant, and the overall high-frequency loss in the glass case at 25 Mbps was practically nil. The signal delay is less on barbed wire than on an equivalent length of PVC-insulated Category 3 wiring, due to the use of an air dielectric between the barbed strands. You can intentionally set the spacing to create almost any impedance you want. Inside the glass case, the spacing between barbed strands was set to create an impedance of 100 Ω.

In summary, the barbed wire had zero impact on signal quality. The signals went through perfectly undistorted. The only thing the barbed wire did was impress the heck out of Broadcom’s customers.

Besides Ethernet running over many barbed wires, the are also demos that run high speed data over one pair of barbed wires. Westermo has demonstrated Ethernet extension based on SHDSL technology running over a pair of barbed wire. The wire pair doesn’t have to be barbed wire, but it does look rather cool for this demo. If you need to run data over barbed wire over some real distance, this might be the practical way to do it. SHDSL technology allows running quite high data speeds over quite long distance old wiring.
Westermo Ethernet extender demo over barbed wire!
https://www.youtube.com/watch?v=LP3amXkjvPg

Links to more information on ADSL over wet strings:

https://www.revk.uk/2017/12/its-official-adsl-works-over-wet-string.html
https://hackaday.com/2017/12/14/adsl-robustness-verified-by-running-over-wet-string/
https://www.zdnet.com/article/fact-broadband-really-does-work-over-a-piece-of-wet-string
https://www.techpowerup.com/forums/threads/dsl-broadband-over-wet-string.239701/

Barbed wire Ethernet links:
https://www.sigcon.com/Pubs/edn/SoGoodBarbedWire.htm
https://www.wband.com/2002/05/wideband-gigabit-ethernet-over-barbed-wire-catches-fancy-of-national-magazine/
https://www.reddit.com/r/networking/comments/17g0b4/ethernet_over_barbed_wire/
https://www.quora.com/Is-it-true-that-someone-ran-Ethernet-over-barbed-wire-and-if-so-WHY
https://news.ycombinator.com/item?id=15910263
https://forums.tomshardware.com/threads/gigabit-over-barbed-wire.958476/

Barbed wire telephone links:

Phones, modems and barbed wire!
https://www.wanderingaustralia.com.au/the-phones-are-driving-me-mad/

Barbed Wire Telephone Lines Brought Isolated Homesteaders Together
And then let them snoop on each other
https://www.atlasobscura.com/articles/barbed-wire-telephone-lines-homesteaders-prairie-america-history

When fences became phones: The unexpected use of barbed wire
https://www.kttn.com/when-fences-became-phones-the-unexpected-use-of-barbed-wire/

Atrocious but efficient: How ranchers used barbed wire to make phone calls
A barbed wire telephone call didn’t sound great but could quickly warn others about something such as a wildfire.

https://www.texasstandard.org/stories/atrocious-but-efficient-how-ranchers-used-barbed-wire-to-make-phone-calls/

https://en.wikipedia.org/wiki/Barbed_wire_telephone_lines

https://www.agriculture.com/podcast/successful-farming-podcast/barbed-wire-telephones-connected-the-old-frontier

Barbed Wire Fences Were An Early DIY Telephone Network
https://gizmodo.com/barbed-wire-fences-were-an-early-diy-telephone-network-1493157700

The Daily Herald
Delphos, OH, United States, Thursday, April 19, 1900
vol. 6, no. 266, p. 3, col. 5-6
BARB-WIRE TELEPHONE LINE.
Three Towns in Indiana Connected by Using Ordinary Fence Wires.
https://reference.insulators.info/publications/view/?id=5740

TEXAS HISTORY
Wired for Sound
Between you, me and the fence post, barbed-wire telephone systems kept rural folks hanging on every word
https://texascooppower.com/wired-for-sound/

Video
BARBED WIRE TELEPHONE LINE
https://www.youtube.com/watch?v=koEkQ3EqyNk

When building a small home ethernet network, we normally use switch to connect all cables together. Historically, the main reason for purchasing hubs rather than switches was their price. By the early 2000s, there was little price difference between a hub and a low-end switch. Hubs can still be useful in special circumstances like for analyzing network traffic (usually nowadays done with a managed switch or network taps) and some special real-time networks (Ethernet PowerLink). The difference between a basic switch and a hub is that a hub broadcasts the packets to all other links. A switch is smarter and only sends packets to links that require it.

The term Passive Ethernet hub can mean to different things: an Ethernet hub that does not need any external power to work or some type of intelligent hubs that supervises traffic going through the hub. In this article I cover the passive hub that does not need any external power. Ethernet hubs can be passive, however they are limited in connectivity range by the signal loss through cabling and the hub and only limited to support 10BASE-T standard. They have not been made by any company for a long time as far as I know. Passive hubs were once sometimes used to organize and physically maintain cables from a single source. Passive hubs can be used together with active or intelligent hubs.

There are designs available to build them yourself. Those passive hubs are quite simple devices without power supply and they simply connected all cables together (with a few diodes or something logically equivalent).

Passive hub using 10BASE-T half duplex – Ethernet (IEEE 802.3)

I am used to see passive Ethernet hub circuit based on diodes. Building a Passive Ethernet Hub and Building a passive ethernet hub with anti-parallel diodes web pages both show this same design that is believed to be correct (although I have not personally built it):

There is one Ethernet HUB Passive design for EasyEDA on-line design software at
https://easyeda.com/modules/Ethernet-HUB-Passive_ab43e58c17334d6a8834e61a75252c1a

The diodes are BA243 or BA244, PIN diodes. There are 24 of them on a tiny piece of PCB inside the little plastic case.

The hub’s vital task is to enable each adapter to ‘hear’ everything others transmit, but at the same time to prevent each adapter from hearing itself sending data. While working half-duplex, each Ethernet adapter is continously monitoring its recieving pair of conductors (pins 3 and 6) for any traffic and will not start sending its data as long as anything else is being transferred through the medium. Even when already transmitting, the Ethernet adapter will fall silent as soon as any other traffic appears. This event is called ‘collision’ and is resolved by both computers waiting for pseudo-random periods of time before trying again.

How does this circuit work and avoid collisions? The basic idea of this circuit is that when one connected Ethernet card is sending, the output signal goes to the input of all other connected Ethernet cards, but not to the input if the card that is sending (getting own signal back would make the Ethernet card to think that there is a collision happening).

There is some description on this at https://forum.allaboutcircuits.com/threads/need-a-passive-ethernet-hub.40182/

I’m also thinking that the way that diode hub was wired, one needs an odd number of connections (either three or five); since the original used diodes with a Vf of ~1v, a 5-connection passive hub would need to use diodes with a Vf of 3/5 or 0.6v at the same current level. Perhaps 1N914 or 1N4148 diodes would be worth considering. I simply don’t know offhand.

I didn’t dig into the specs too far but ethernet is only a couple of volts, somewhere between 2 and 4, and the actual far end detection threshold is only a few hundred mv’s. So a diode drop or two or even three shouldn’t hurt anything. I don’t remember ANY of the details but I do know when I first used ethernet that passive four port hubs were queit common and for close quarters 4-8 ports were available.

Comments from http://www.circuit-diagrams.net/page/a-passive-ethernet-hub

“I tested this concept on a little network consisting of three PCs running under Windows 2000. It works well. The network adapters are normal Intel and 3Com models, set to 10 Mbps and Half Duplex. The computers are labelled A, B, C, and the UTP cables from the computers to the hub are 10, 16 and 35 meters long, respectively.”

But why? Why not? The voltage drop over the diodes between xmt and rcv for each leg is high enough so Ethernet cards can’t see itself – but can see the others. This circuit idea probably only works for exactly 3 legs. Each diode have a voltage drop, so if you apply voltage between A1, A3 there will be voltage drop across each diode, and both B and C computers will receive signal = voltage drop on 1 diode. In half-duplex mode what happens when two hosts start to transmit at the same time? I think when A tries do drive low and B tries to drive high, their signals will mutually clamp each other to ± one diode drop which is not enough to pass through other diodes to each other’s RX port. And the third C host sees a zero signal at its RX at that time. So it looks like setting the hosts for half-duplex is important for avoiding packet loss.

Traffic collisions and voltage drop make the passive hub impractical for large networks or any decent distance. The diodes will heavily attenuate the signal so it probably won’t work over longer distances. And this only works for 10BASE-T Ethernet standard that uses half duplex operation mode. The newer faster Ethernet standard use full duplex operation, different signal formats and lower signal levels, so they do not work with this circuit. Who knows for sure what will happen to autonegotiation here. Disabling autoneg and manually forcing half-duplex is probably necessary for ‘reliable’ operation. If autoneg fails (as it probably will in a significant proportion of cases), that will result in half-duplex link too, but I wouldn’t want to count on that.

Someone seems to have tried to make his/her own design based on resistors and posted it to Facebook:

There are views at https://electronics.stackexchange.com/questions/10864/building-a-passive-ethernet-hub-with-anti-parallel-diodes that resistor idea might not work well:

You cannot use resistors since they would linearly attenuate the signal and after going all the way around the loop it would finally reach your own RX line. It would be attenuated but the receiver circuit is very sensitive so it would still be able to detect is as a collision. You need a nonlinear element (like a diode) that provides a sharp cutoff.

Links to sources and more information:

Need a passive ethernet hub
https://forum.allaboutcircuits.com/threads/need-a-passive-ethernet-hub.40182/

IEEE Standards (free download)
http://standards.ieee.org/getieee802/802.3.html

Ethernet: Negotiating Speed and Duplex
https://www.youtube.com/watch?v=kb1nLfaJ3Go

https://forums.tomshardware.com/threads/small-ethernet-hub-question.1833679/

Passive Ethernet Hub
https://easyeda.com/modules/Passive-Ethernet-Hub_6c43ae8c904b4d16a678ea548d0cd817

A Passive Ethernet Hub
http://www.circuit-diagrams.net/page/a-passive-ethernet-hub

http://www.circuit-diagrams.net/uploads/1/91/a-passive-ethernet-hub_1408376960_max.jpg

Building a Passive Ethernet Hub
https://www.eeweb.com/building-a-passive-ethernet-hub/

Building a passive ethernet hub with anti-parallel diodes
https://electronics.stackexchange.com/questions/10864/building-a-passive-ethernet-hub-with-anti-parallel-diodes

https://www.eevblog.com/forum/projects/has-anyone-had-any-success-building-a-passive-ethernet-hub-with-just-diodes/

Battery-Powered Ethernet Hub
http://kan.org/networking/batteryhub.html

https://www.eeweb.com/building-a-passive-ethernet-hub/

https://easyeda.com/modules/Passive-Ethernet-Hub-copy_707e25d3348b40b5993a0c6db602b3a0

https://www.eeweb.com/building-a-passive-ethernet-hub/

https://www.eevblog.com/forum/projects/has-anyone-had-any-success-building-a-passive-ethernet-hub-with-just-diodes/

https://electronics.stackexchange.com/questions/10864/building-a-passive-ethernet-hub-with-anti-parallel-diodes

http://www.zen22142.zen.co.uk/Circuits/Interface/pethhub.htm

Heres a pre-layed out board
https://easyeda.com/kisly.va/passive-ethernet-hub-pin-diode

https://www.eevblog.com/forum/projects/has-anyone-had-any-success-building-a-passive-ethernet-hub-with-just-diodes/

https://en.wikipedia.org/wiki/Ethernet_hub

https://www.minitool.com/lib/ethernet-hub.html

https://superuser.com/questions/582805/ethernet-hub-is-it-an-active-device

https://www.reddit.com/r/networking/comments/3bgkmd/where_can_i_get_a_passive_hub_nowadays/

https://wiki.wireshark.org/CaptureSetup/Ethernet

In 1979 he started a little company called 3com.
Ethernet was commercially introduced in 1980 and first standardized in 1983 as IEEE 802.3. Ethernet has since been refined to support higher bit rates, a greater number of nodes, and longer link distances, but retains much backward compatibility. Over time, Ethernet has largely replaced competing wired LAN technologies.

Analog Devices single pair Ethernet demo with 400 meters of cable

Avnet Embedded gave me some Belgian chocolate

Smarc vs new smaller OSM module

Unshielded but not so twisted wire pairs in this Ethernet cable

It is essentially multiple twin lead transmission lines, but yeah, lacking the benefits of twisting.

And there is that one “split pair” that goes to pins 3 and 6. If other pairs are close what they should, this definitely has wrong impedance and more noise pick up.

Yeah this cable probably performs like crap.

The recommended approach for implementing PoE is to use Ethernet switches that support PoE. Mid-span injectors can easily be purchased which will add Power-over-Ethernet (PoE) to an existing Ethernet signal without need to upgrade to PoE switches. The downside, of course, is cost of many known brands. If you are looking to save money, you might want to look what is the “cheap Chinese solution”. I decided to try a cheap “generic” PoE injector often referred to as just POE-48005.

I got my power supply from some web shop. The same product is sold in many places. Here is one description:

POE Injector 48V 0.5A Adapter EU Plug – XR-48005

Wide input voltage 100VAC-240VAC AC-DC POE Injector 48V 0.5A POE Wall Plug Ethernet Adapter with EU Plug.

Description
Wide input voltage 100VAC-240VAC AC-DC POE Injector 48V 0.5A POE Wall Plug Ethernet Adapter with EU Plug. A POE injector adapter connects to regular Ethernet cable on its one RJ45 connector and injects 48V/0.5A DC power on its output RJ45 connector. On Ethernet data POE injector acts as pass through device that mixes data and power on Ethernet cable. The devices requiring Power from Ethernet cable then can work by use of this POE Injector.

Applications
POE Powered IP Cameras and surveillance devices
Arduino POE capable Ethernet Shields requiring Power over Ethernet
Custom Designed POE powered modules / devices such as remote sensors

Features
Provides remote power to equipment through CAT 5 Ethernet cable up to 100M
Autoranging switching power supply 100~240V AC
Short circuit, over-current, and over-voltage protection
Reliable 24W passive POE output
Compact, portable size with convenient wall plug design
Technical Specifications
Output: 48V DC 500mA – Please do not order if your unit requires more than 500 MilliAmps
Input: 100-240V 50/60HZ
Output: 48V-0.5A
Input Current: 1A
Efficiency: 80% Min
Line / Load Regulation: 3% / 5%
Ripple / Noise: 200mV p-p
Turn-On Delay: 2 Seconds Max
Rise Time: 40 mS Max
Protections: Auto Recover Over-Voltage, Short Circuit, Over-Current
Environmental Standards: RoHs
Operating Temperature: -10 to +40°C (14 to +104°F)
Operating Humidity (RH): 5% – 90%
Storage Temperature: -20 to +85°C (-4 to +185°F)

When I was testing this power supply it seemed to always supply 48V even though the original description I saw mentioned IEEE 802.3af standard, which says that the power supply device should identify that there is PoE capable device connected before supplying that 48V to cable. It seems that this power supply does not meet the IEEE 802.3af standard as power source. It power IEEE 802.3af standard compliant devices though. But because it is missing that IEEE 802.3af identification part, it could damage if you plug in a device that does not expect to receive PoE power.

I was planning to do a more detailed review of this device, but then I found this excellent review of one version of the POE-48005 power supply that describes well that is going on.

Review: Generic 48V 802.3af “Compatible” PoE Injector (XLY-POE-48005)
Posted on December 4, 2022 by lui_gough
https://goughlui.com/2022/12/04/review-generic-48v-802-3af-compatible-poe-injector-xly-poe-48005/

I decided to scrape the bottom of the barrel for this “generic” PoE injector (often referred to as just POE-48005) for about AU$11.20 each by stacking some coupons. I was curious – just what will I get?

POE power supply, Model POE-48005, accepting 100-240V AC at 50/60Hz and providing 48V 0.5A with positive on pins 4 and 5, negative on pins 7 and 8. The item is Made in China,

At the end, there are two 8p8c sockets – one marked LAN for data input and one marked POE for power and data output to the device. Do not get this the wrong way around!

Key snippets from the sales listing include these somewhat potentially contradictory and misleading statements, especially if skimming the listing:

“CAT5 Ethernet Pin Usage: Data: 1,2,3,6 Power: +(4,5),-(7,8)”
“Standards: 802.3af”

“Meeting IEEE 802.3af standards and more sufficiently is able to provide power to PD devices”

“This Adapter only support 10/100M connection, do not support gigabit ethernet connection, because Data & Power Out port using 4,5,7,8 pin as power transfer, Please do not connect any gigabit ethernet device on “Out” port, this will damage your device.”

“This is an 802.3af compatible device, but it does NOT include the 802.3af compliant detection feature. It supplies power NO MATTER WHAT, so don’t plug the “POE” side into anything that isn’t ready for it.”

As a result, it’s clear that this is not an 802.3af compliant injector. By “compatible”, they mean that it will work as the wiring is the same as Mode B and the voltage is also within the range, so the connected device should run. But it doesn’t have any of the safeguards that 802.3af requires, so plugging it into devices that aren’t expecting PoE is likely to cause damage. It won’t allow gigabit Ethernet either, since no magnetics are used in the injection. Damage to gigabit devices, may only affect certain designs. This is basically equivalent of bundling a “passive” PoE injector with a 48V supply – with the benefit of being inexpensive and relatively neat.

I suppose the interesting thing is that I learned that the PoE load detection procedure can be done by the switch port, but the device doesn’t expect to need to go through the sequence – if power is available, it will just seemingly take it.

From the top, it seems that the design itself is rather minimalist, but is not entirely horrible.

The Ethernet input pins 4, 5, 7 and 8 are completely disconnected from the PCB

While the design didn’t exactly ring any alarm bells, the electrolytic capacitors did leave me some pause for concern.

The results appear to show very stable voltage output of about 49V which is well within the 44-57V range.

Conclusion
The price for skimping on an 802.3af power injector is receiving a product that is a 48V DC power supply and passive Mode B compatible PoE injector combined into the one case. Such a design will work with 802.3af devices and in that sense is “compatible”, but does not have any of the device detection logic that makes the system safe for conventional Ethernet devices. Reversing the connections could lead to harm to conventional Ethernet devices,

The efficiency is not horrible and the power supply design looks sensible enough, but the quality of the electrolytics leaves much to be desired. Perhaps it would have been better to spend those few extra dollars to get something proper in the long run … both for safety and for longevity. Still, at least I was able to satisfy my curiosity!

At first Ethernet technology remained primarily focused on connecting up systems within a single facility, rather than being called upon for the links between facilities, or the wider Internet. Ethernet at short distances has primarily used copper wiring. Fiber optic connections have also been available for the transmission of Ethernet over considerable distances for nearly two decades.

Today, Ethernet is everywhere. It’s evolved from a 2.93-Mb/s and then 10-Mb/s coax-based technology to one that offers multiple standards using unshielded twisted pair (UTP) and fiber-optic cable with speeds over 100 Gb/s. Ethernet, standardized by the IEEE as “802.3,” now dominates the networking world. And the quest for more variations continues onward.

Ethernet has always had the ability to communicate over reasonably large lengths of wiring, with even the very first prototype using 1km of copper cabling. Although Gigabit Ethernet over copper twisted pair cabling is only specified for 100m between links, fiber optic versions have allowed Ethernet to run over single connections up to 70km each.

Ethernet is on the Way to Total Networking Domination. Ethernet is all over the place. Most of us use it day by day. The first coax-primarily based Ethernet LAN conceived in 1973 by Bob Metcalfe and David Boggs. Since then Ethernet has grown to the stage of pretty much entire local area networking goes through it (even most WiFi hot spots are wired with Ethernet). It’s hard to overestimate the importance of Ethernet to networking over the past 25 years, during which we have seen seen Ethernet come to dominate the Networking industry. Ethernet’s future could be even more golden than its past.

Ethernet has pretty much covered office networking and backbones industrial networks. In industrial applications there applications where Ethernet is still coming. Ethernet is on the Way to Total Networking Domination article says that single-pair Ethernet makes possible cloud-to-sensor connections that enable full TCP/IP, and it’s revolutionizing factory automation. This technology will expand the use of Ethernet on the industrial applications. Several different single-pair Ethernet (SPE) standards seeks to wrap up full networking coverage by addressing the Internet of Things (IoT), and specifically the industrial Internet of Things (IIoT) and Industry 4.0 application space.

Traditional copper Ethernet

Started with 50 ohms coax in 1973. In the 1990′s the twisted pair Ethernet with RJ-45 connectors and fiber became the dominant media choices. Modern Ethernet versions use a variety of cable types.

Twisted pair Ethernet mainstream use stared with CAT 5 cable that has been long time used for 100 Mbps or slower plans, while CAT 5a cables and newer are ideal for faster speeds. Both CAT5e and CAT6 can handle speeds of up to 1000 Mbps, or a Gigabit per second.

Today, the most common copper cables are Cat5e, Cat6, and Cat6a. Now twisted pair the main media (CAT 6A, CAT7, CAT8 etc.) can handle speeds from 10M to 10G with mainstream devices, typically up to 100 meters. All those physical layers require a balanced twisted pair with an impedance of 100 Ω. Standard CAT cable has four wire pairs, and different Ethernet standards use two of them (10BASE-T, 100BASE-TX) or all four pairs (1000BASE-T and faster).

Many different modes of operations (10BASE-T half-duplex, 10BASE-T full-duplex, 100BASE-TX half-duplex, etc.) exist for Ethernet over twisted pair, and most network adapters are capable of different modes of operation. Autonegotiation is required in order to make a working 1000BASE-T connection. Ethernet over twisted-pair standards up through Gigabit Ethernet define both full-duplex and half-duplex communication. However, half-duplex operation for gigabit speed is not supported by any existing hardware.

In the past, enterprise networks used 1000BASE-T Ethernet at the access layer for 1 Gb/s connectivity over typically Cat5e or Cat6 cables. But the advent of Wi-Fi 6 (IEEE 802.11ax) wireless access points has triggered a dire need for faster uplink rates between those access points and wiring closet switches preferably using existing Cat5e or Cat6 cables. As a result, the IEEE specified a new transceiver technology under the auspices of the 802.3bz standard, which addresses these needs. The industry adopted the nickname “mGig,” or multi-Gigabit, to designate those physical-layer (PHY) devices that conform to 802.3bz (capable of 2.5 Gb/s and 5 Gb/s) and 802.3an (10 Gb/s). mGig transceivers fill a growing requirement for higher-speed networking using incumbent unshielded twisted-pair copper cabling. The proliferation of mGig transceivers, which provide Ethernet connectivity with data rates beyond 1 Gb/s over unshielded copper wires, has brought with it a new danger: interference from radio-frequency emitters that can distort and degrade data-transmission fidelity.

10GBASE-T is the standard technology that enables 10 Gigabit Ethernet operations over balanced twisted-pair copper cabling system, including Category 6A unshielded and shielded cabling.

CAT8 can go even higher speeds up to 40G up to 30 meters. Category 8, or just Cat8, is the latest IEEE standard in copper Ethernet cable. Cat8 is the fastest Ethernet cable yet. Cat8 support of bandwidth up to 2 GHz (four times more than standard Cat6a bandwidth) and data transfer speed of up to 40 Gbps. Cat 8 cable is built using a shielded or shielded twisted pair (STP) construction where each of the wire pairs is separately shielded. Shielded foil twisted pair (S/FTP) construction includes shielding around each pair of wires within the cable to reduce near-end crosstalk (NEXT) and braiding around the group of pairs to minimize EMI/RFI line noise in crowded network installations. Cat 8 Ethernet cable is ideal for switch to switch communications in data centers and server rooms, where 25GBase‑T and 40GBase‑T networks are common. Its RJ45 ends will connect standard network equipment like switches and routers. Cat8 cable supports Power over Ethernet (PoE) technology. Cat8 is designed for a maximum range of 98 ft (30 m). If you want fater speeds and/or long distance there are various fiber interfaces.

Power over Ethernet

Power over Ethernet (PoE) offers convenience, flexibility, and enhanced management capabilities by enabling power to be delivered over the same CAT5 or higher capacity cabling as data. PoE technology is especially useful for powering IP telephones, wireless LAN access points, cameras with pan tilt and zoom (PTZ), remote Ethernet switches, embedded computers, thin clients and LCDs.

The original IEEE 802.3af-2003 PoE standard provides up to 15.4 W of DC power (minimum 44 V DC and 350 mA) supplied to each device. The IEEE standard for PoE requires Category 5 cable or higher (can operate with category 3 cable for low power levels). The updated IEEE 802.3at-2009 PoE standard also known as PoE+ or PoE plus, provides up to 25.5 W (30W) of power.

IEEE 802.3bt is the 100W Power over Ethernet (PoE) standard. IEEE 802.3bt calls for two power variants: Type 3 (60W) and Type 4 (100W). This means that you can now carry close to 100W of electricity over a single cable to power devices. IEEE 802.3bt takes advantage of all four pairs in a 4-pair cable, spreading current flow out among them. Power is transmitted along with data, and is compatible with data rates of up to 10GBASE-T.

Advocates of PoE expect PoE to become a global long term DC power cabling standard and replace a multiplicity of individual AC adapters, which cannot be easily centrally managed. Critics of this approach argue that PoE is inherently less efficient than AC power due to the lower voltage, and this is made worse by the thin conductors of Ethernet.

Cat5e cables usually run between 24 and 26 AWG, while Cat6, and Cat6A usually run between 22 and 26 AWG. When shopping for Cat5e, Cat6, or Cat6a network cables, you might notice an AWG description printed on the cable jacket such as: 28AWG, 26 AWG, or 24AWG. AWG stands for American wire gauge, a system for defining the diameter of the conductors of a wire which makes up a cable. The larger the wire gauge number, the thinner the wire and the smaller the diameter.

One of the newest types of Ethernet cables on the market, Slim Run Patch Cables, actually have a 28 AWG wire. This allows these patch cords to be at least 25% smaller in diameter, than standard Cat5e, Cat6, and Cat6a Ethernet. Smaller cable diameter is beneficial for high-density networks and data centers.

The downside of 28 AWG cable is higher resistance and power loss in PoE applications. Before February 2019, the short answer to “Can 28 AWG patch cords be used in PoE applications?” was “no.” Today, however, the answer is “yes”! 28 AWG patch cords can now be used to support power delivery.

It has been approved that 28 AWG cables can support power delivery and higher PoE levels with enough airflow around the cable. According to TSB-184-A-1, an addendum to TSB-184-A: 28 AWG patch cabling can support today’s higher PoE levels, up to 60W.

To maintain recommendations for temperature rise, 28 AWG cables must be grouped into small bundles. By keeping 28 AWG PoE patch cords in bundles of 12 or less, the impacts of cable temperature rise are diminished thus allowing you to stay within the suggested maximum temperature rise of 15 degrees Celsius. Per TSB-184-A-1, an addendum to TSB-184-A: 28 AWG in bundles of up to 12 can be used for PoE applications up to 30W.In PoE applications using between 30W and 60W of power, spacing of 1.5 inches between bundles of 12 cables is recommended. Anything above 60W with 28 AWG cable requires authorization from the authority in USA.

There is no installation location or bundle size limitations for 28 AWG cord cables when power is not being distributed over the data network. The limitations only apply when PoE comes into play. Another thing you should bear in mind is that 28 AWG wires should never be used as horizontal, or “backbone” cabling as their maximum distance according to the standards is 10 meters.

Single pair Ethernet

Several different single-pair Ethernet (SPE) standards seeks to wrap up full networking coverage by addressing the Internet of Things (IoT), and specifically the industrial Internet of Things (IIoT) and Industry 4.0 application space.

Single Pair Ethernet, or SPE, is the use of two copper wires that can transmit data at speeds of up to 1 Gb/s over short distances. In addition to data transfer, SPE has option to simultaneously delivering Power over Dataline (PoDl). This could be a major step forward in factory automation, building automation, the rise of smart cars, and railways. Single-pair Ethernet (SPE) allows legacy industrial networks to migrate to Ethernet network technology whilst delivering power and data to and from edge devices.

Traditional computer-oriented Ethernet comes normally in two and four-pair variants. Different variants of Ethernet are the most common industrial link protocols. Until now, they have required 4 or 8 wires, but the SPE link is allows using only two wire pairs. Using only two wire pairs can simplify the wiring and can allow reusing some old industrial wiring for Ethernet application. SPE offers additional benefits such as lighter and more flexible cables. Their space requirements and assembly costs are lower than with traditional Ethernet wiring. Those are the reasons why the technology is of interest to many.

The 10BASE-T1, 100BASE-T1 and 1000BASE-T1 single-pair Ethernet physical layers are intended for industrial and automotive applications or as optional data channels in other interconnect applications.
Automotive Ethernet, called 802.3bw or 100BASE-T1, that adapts Ethernet to the hostile automotive environment with a single pair.

Also 2.5 Gb/s, 5 Gb/s, and 10 Gb/s over a 15 m single pair is standardized in 802.3ch-2020. As of 2021, the P802.3cy Task Force is examining having 25, 50, 100 Gb/s speeds at lengths up to 11 m.

The single pair operates at full duplex and has a maximum reach of 15 m or 49 ft (100BASE-T1, 1000BASE-T1 link segment type A) or up to 40 m or 130 ft (1000BASE-T1 link segment type B) with up to four in-line connectors.

There is also a long distance 10BASE-T1L standard that can support distance up to one one kilometer at 10-Mb/s speed. In building automation, long reach is often needed for HVAC, fire safety, and equipment like elevators. The 10BASE-T1 standard has two parts. The main offering is 10BASE-T1L, or long reach to 1 km. The connection is point-to-point (p2p) with full-duplex capability. The other is 10BASE-T1S, or short-reach option that provides p2p half-duplex coverage to 25 meters and includes multidrop possibilities.

All those physical layers require a balanced twisted pair with an impedance of 100 Ω. The cable must be capable of transmitting 600 MHz for 1000BASE-T1 and 66 MHz for 100BASE-T1.

Single-pair Ethernet defines its own connectors:

• IEC 63171-1 “LC”: This is a 2-pin connector with a similar locking tab to the modular connector, if thicker.
• IEC 63171-6 “industrial”: This standard defines 5 2-pin connectors that differ in their locking mechanisms and one 4-pin connector with dedicated pins for power. The locking mechanisms range from a metal locking tab to M8 and M12 connectors with screw or push-pull locking. The 4-pin connector is only defined with M8 screw locking.

Fiber Ethernet

When most people think of an Ethernet cable, they probably imagine a copper cable, and that’s because they’ve been around the longest. A more modern take on the Ethernet cable is fiber optic. Instead of depending on electrical currents, fiber optic cables send signals using beams of light, which is much faster. In fact, fiber optic cables can support modern 10Gbps networks with ease. Fiber optic has been option on Ethernet for a long time. Ethernet has been using optical fiber for decades. The first standard was 10 Mbit/s FOIRL in 1987. The currently fastest PHYs run 400 Gbit/s. 800 Gbit/s and 1.6 Tbit/s started development in 2021.

The advantage most often cited for fiber optic cabling – and for very good reason – is bandwidth. Fiber optic Ethernets can easily handle the demands of today’s advanced 10 Gbps networks or 100Gbps, and have the capability of doing much more. Fiber optic cables can run without significant signal loss for distances, from kilometers up to tens of kilometers depending on the fiber type and equipment used.

The cost of fiber has come down drastically in recent years. Fiber optic cable is usually still a little more expensive than copper, but when you factor in everything else involved in installing a network the prices are roughly comparable.

Fiber optics is immune to the electrical interference problems because fiber optic cable doesn’t carry electricity, it carries light. Because fiber optic cables don’t depend on electricity, they’re less susceptible to interference from other devices.

Fiber optic cables are sometimes advertised to be more secure than copper cables because light signals are more difficult to hack. It is true that light signals are slightly more difficult to hack than copper cable signals, but actually they are nowadays well hackable with right tools.

Fiber has won the battle in the backbone networks on long connections, but there is still place for copper on shorter distances Nearly every computer and laptop sold today has a NIC card with a built-in port ready to accept a UTP copper cable, while a potentially expensive converter or fiber card is required to make a fiber optic cable connection.

Standard fiber-optic cables have a glass quartz core and cladding. Nowadays, there are two fiber optic cable types widely adopted in the field of data transfer—single mode fiber optic cable and multimode fiber optic cable.

A single-mode optical fiber is a fiber that has a small core, and only allows one mode of light to propagate at a time. So it is generally adapted to high speed, long-distance applications. The core size of single mode fiber has a core diameter between 8 and 10.5 micrometers with and a cladding diameter of 125 micrometers. OS1 and OS2 are standard single-mode optical fiber used with wavelengths 1310 nm and 1550 nm (size 9/125 µm) with a maximum attenuation of 1 dB/km (OS1) and 0.4 dB/km (OS2). SMF is used in long-haul applications with transmission distances of up to 100 km without need a repeater. Typical transmission distances are up 10-40 kilometers. Single mode capable hardware used to be very expensive years ago, but prices for then have came down quicly. Nowadays single mode is very commonly uses.

Multimode optical fiber is a type of optical fiber with a larger core diameter larger (65 or 50 micrometer core) designed to carry multiple light rays, or modes at the same time. It is mostly used for communication over short distances. Multimode Fiber (MMF) uses a core/cladding diameter of typically 50 micrometer/125 mictometer, providing less reach, up to approximately 2 km or less, due to increased dispersion as a result of the larger diameter core.

Image fromhttps://www.cables-solutions.com/whats-difference-fiber-optic-cable-twisted-pair-cable-coaxial-cable.html:

Fiber has become common in datacenters due to the frequency and reach limitations of twisted-pair copper – currently and probably permanently limited to 40 Gbit/s over only 30 m of category-8 twisted pair or just 10 Gbit/s over the full 100 m (of category 6A).

Fiber optic cables are commonly used for core network lines and connections that must span long distances, such as those used by Internet service providers.

Depending on your requirements, when going to use fiber, you’re probably first looking for one of these commonly used interfaces: 1000BASE-SX (1 Gbit/s over up to 550 m of OM2 multi-mode fiber), 1000BASE-LX (1 Gbit/s over up to 10 km of single-mode fiber), 10GBASE-SR (10 Gbit/s over up to 400 m of OM4 MMF), 10GBASE-LR (10 Gbit/s over up to 10 km of SMF).

There are many other PHY standards for various data rates and distances, also many common non-standards for even longer distance. The required optical transceivers are usually SFP (1G) or SFP+ modules (10G) plugged into your network hardware. Switches and network adapters with SFP modules allow you to create custom fiber optic high-speed Ethernet networks by plugging in suitable type SFP module. External media converters for devices without SFP slot are also available. A fiber media converter, also known as a fiber to Ethernet converter, allows you to convert typical copper Ethernet cable (e.g., Cat 6a) to fiber and back again.

100G (100 Gb/s) Ethernet has had a good run as the backbone technology behind the cloud, but the industry is moving on. There is expected to be exploding demand for bandwidth in the 5G/mmWave era that’s now upon us. Modern
400G and 800G test platforms validate the cloud’s Ethernet backbone, ensuring support for the massive capacity demands of today and tomorrow. Many service providers and data centers, for various reasons, skipped over 400G Ethernet implementations and are looking toward 800G Ethernet for their next network transport overhaul. Adoption of 400G is still happening, but the growth of 800G will eclipse it before long.

In the future, the speeds of Ethernet networks will increase. Even after the 25, 40, 50 and 100 gigabit versions, more momentum is needed. For example, growing traffic in data centers would require 100G or even faster connections over long distances. Regardless of future speed needs, 200G or 400G speeds are best suited for short-term needs. The large cloud data centers on the Internet have moved to 100GbE, 200GbE and 400G solutions for trunk connections. They also require strong encryption and, in addition, accurate time synchronization of the backbone networks of 5G networks. Media Access Control security (MACsec) provides point-to-point security on Ethernet links. MACsec is defined by IEEE standard 802.1AE. IEEE 802.1X is an IEEE Standard for port-based Network Access Control (PNAC).

High-speed terabit rates do not yet make sense to implement now. The standardization organization OIF (Optical Interworking Forum) has worked up to 800 gigabit connection speeds. The Ethernet Technology Consortium proposed an 800 Gbit/s Ethernet PCS variant based on tightly bundled 400GBASE-R in April 2020. In December 2021, IEEE started the P802.3df Task Force to define variants for 800 and 1600 Gbit/s over twinaxial copper, electrical backplanes, single-mode and multi-mode optical fiber along with new 200 and 400 Gbit/s variants using 100 and 200 Gbit/s lanes. Lightwave magazine expects that 800G Ethernet transceivers become most popular module in mega data centers by 2025. There are already test instruments designed to validate 1.6T designs.

There is also one fiber tpye I have not mentioned yet. Plastic optical fiber (POF) has emerged as a low cost alternative to twisted pair copper cabling and coaxial cables in office, home and automotive networks. POF technology offers an attractive alternative to traditional glass optical fiber as well as copper for industrial, office, home and automotive networks. POF typically utilizes a polymethylmethacrylate (PMMA) core and a fluoropolymer cladding. Glass fiber-optic cable offers lower attenuation than its plastic counterpart, but POF provides a more rugged cable, capable of withstanding a tighter bend radius.

POF has generally been utilized in more niche applications where its advantages outweigh the need for high bandwidth and relatively short maximum distance (only tens of meters). Currently in the market, several manufacturers have developed fiber optic transceivers for 100Mbps Ethernet over plastic optical fiber and there exist also 1Gbit/s versions. Advances in LED technology and Vertical Cavity Surface Emitting Laser (VCSEL) technology are enabling POF to support data rates of 3Gbps and above

POF offers many benefits to the user: it is lightweight, robust, cheap and easy to install; the use of 650nm red LED light makes it completely safe and easier to diagnose as red light can be seen by the human eye. There are several different connectors used for PoF. There is also connector-less option called Optolock, where you can simply slice the plastic fiber with a knife, separate the fibers, insert the fiber into the housing and then lock it in place.

Industrial networks special demands for Ethernet

Industrial networks need to be durable. Industrial applications on the field needs often more durable connectors than the traditional RJ-45 connector of office networks.

Here is a list of some commonly used industrial Ethernet connector types:

• 8P8C modular connector: For stationary uses in controlled environments, from homes to datacenters, this is the dominant connector. Its fragile locking tab otherwise limits its suitability and durability. Bandwidths supporting up to Cat 8 cabling are defined for this connector format.
• M12X: This is the M12 connector designated for Ethernet, standardized as IEC 61076-2-109. It is a 12mm metal screw that houses 4 shielded pairs of pins. Nominal bandwidth is 500MHz (Cat 6A). The connector family is used in chemically and mechanically harsh environments such as factory automation and transportation. Its size is similar to the modular connector.
• ix Industrial: This connector is designed to be small yet strong. It has 10 pins and a different locking mechanism than the modular connector. Standardized as IEC 61076-3-124, its nominal bandwidth is 500MHz (Cat 6A).

In addition to those there are applications that use other versions of M12 and smaller M8 connectors.

Current industrial trends like Industrie 4.0 and the Industrial Internet of Things lead to an increase in network traffic in ever-growing converged networks. Many industrial applications need reliable and low latency communications. Many industries require deterministic Ethernet, and Industrial Automation is one of them. The automation industry has continuously sought solutions to achieve fast, deterministic, and robust communication. Currently, several specialized solutions are available for this purpose, such as PROFINET IRT, Sercos III, and Varan. TSN can help standardize real-time Ethernet across the industry.

TSN refers to a set of IEEE 802 standards that make Ethernet deterministic by default. TSN is an upcoming new technology that sits on Layer 2 of the ISO/OSI Model. It adds definitions to guarantee determinism and throughput in Ethernet networks. It will provide standardized mechanisms for the concurrent use of deterministic and non-deterministic communication. AVB/TSN can handle rate-constrained traffic, where each stream has a bandwidth limit defined by minimum inter-frame intervals and maximal frame size, and time-trigger traffic with an exact accurate time to be sent. Low-priority traffic is passed on best-effort base, with no timing and delivery guarantees. Time-sensitive traffic has several priority classes.

Time-Sensitive Networking (TSN) is a set of standards under development by the Time-Sensitive Networking task group of the IEEE 802.1 working group. The majority of projects define extensions to the IEEE 802.1Q – Bridges and Bridged Networks, which describes Virtual LANs and network switches. These extensions in particular address the transmission of very low transmission latency and high availability. Applications include converged networks with real-time Audio/Video Streaming and real-time control streams which are used in automotive or industrial control facilities.

In contrast to standard Ethernet according to IEEE 802.3 and Ethernet bridging according to IEEE 802.1Q, time is very important in TSN networks. For real-time communication with hard, non-negotiable time boundaries for end-to-end transmission latencies, all devices in this network need to have a common time reference and therefore, need to synchronize their clocks among each other. This is not only true for the end devices of a communication stream, such as an industrial controller and a manufacturing robot, but also true for network components, such as Ethernet switches. Only through synchronized clocks, it is possible for all network devices to operate in unison and execute the required operation at exactly the required point in time. Scheduling and traffic shaping allows for the coexistence of different traffic classes with different priorities on the same network.

The following are some of the IEEE standards that make up TSN:

Enhanced synchronization behavior (IEEE 802.1AS)
Suspending (preemption) of long frames (IEEE 802.1-2018)
Enhancements for scheduled traffic (IEEE 802.1Q-2018)
Path control and bandwidth reservation (IEEE 802.1Q-2018)
Seamless redundancy (IEEE 802.1CB)
Stream reservation (IEEE 802.1Q-2018)

Synchronization of clocks across the network is standardized in Time-Sensitive Networking (TSN). Time in TSN networks is usually distributed from one central time source directly through the network itself using the IEEE 1588 Precision Time Protocol, which utilizes Ethernet frames to distribute time synchronization information.

If you need faster speed or longer distance, you need to use active converters. In essence, the idea is to creates a wired Internet home network, but without the headache of drilling holes or running wires.

There aremany different types of active converters on the market with different specifications. There are many company specific products and there are also products based on some agreed standards. Some standards to get Ethernet-like speed over coaxial cables are HomePNA, MoCA and G.Hn just to mention few available to normal user applications. Cable TV operators use cable modems (usually DOCSIS standard) to run IP data over their cable TV networks.

Most EoC technologies are designed to operate in frequency bands above 1 GHz, which is the upper bound of television signals and for systems designed to operate in North America using the SCTE 55-1 and SCTE 55-2 CATV transmission systems, as well as in most of Europe and portions of Asia.

Commercial passive converters for one 75 ohm coax

There are commercially made passive Ethernet to 75 ohm coax cable converters designed for video surveillance applications. Video surveillance systems have traditionally used 75 ohms coaxial cable to carry analogue (and later in some cases digital) video signal from camera to surveillance center. When IP based digital cameras have become popular, there has been interest to run Ethernet signal over single 75 ohm coaxial cable from surveillance center to the IP camera.

There are many different products marketed for this, some are active devices and some are completely passive devices. For passively adapting 10/100M Ethernet to single 75 ohm coaxial cable, there are product like Monoline Coax Balun – Male BNC to RJ45 jack 10BaseT – 75 Ohm – Each and IP Passive Extender Ethernet Over Coax 1-CH, IP Network to Coaxial Transmitter IP Network Converter Fit CCTV Camera UTP RG59/ RJ45 4-Wired 1236 Cable No. BNC Video Balun Only Fit POE Camera System.

Those are designed to be used for 10 and 100 Mbps speeds only, and do not support any higher speed (like 1G). Dahua also makes converters for the same application.

There are also active adapters designed for IP camera applications in mind for example Ethernet Extender and PoE injector all in one device and Coax to Ethernet Extenders Transmit Ethernet data over Coax.

HomePNA

The HomePNA Alliance is an incorporated non-profit industry association of companies that develops and standardizes technology for home networking over the existing coaxial cables and telephone wiring within homes, so new wires do not need to be installed. It was formerly the Home Phoneline Networking Alliance, also known as HPNA. The original protocols used balanced pair telephone wire. HomePNA 3.1 added Ethernet over coax. HomePNA uses frequency-division multiplexing (FDM), which uses different frequencies for voice and data on the same wires without interfering with each other. A standard phone line has enough room to support voice, high-speed DSL and a landline phone.

HomePNA does not manufacture products. HomePNA creates industry specifications which it then standardizes under the International Telecommunication Union (ITU) standards body. The HomePNA Alliance, tests implementations, and certifies products if they pass.

The HomePNA versions:
HomePNA 1.0 technology was developed by Tut Systems in the 1990s.
HomePNA 2.0 was developed by Epigram and was approved by the ITU as Recommendations G.9951, G.9952 and G.9953.
HomePNA 3.0 was developed by Broadcom (which had purchased Epigram) and Coppergate Communications and was approved by the ITU as Recommendation G.9954 in February 2005.
HomePNA 3.1 was developed by Coppergate Communications[3] and was approved by the ITU as Recommendation G.9954 in January 2007. The original protocols used balanced pair telephone wire. HomePNA 3.1 added Ethernet over coax.

HomePNA 3.1 uses frequencies above those used for digital subscriber line and analog voice calls over phone wires and below those used for broadcast and direct broadcast satellite TV over coax, so it can coexist with those services on the same wires. HomePNA over coax operates between 12 MHz and 44 MHz; the higher start frequency avoids interfering with other services that might be operating over the coax such as VDSL2.

In March 2009, HomePNA announced a liaison agreement with the HomeGrid Forum to promote the ITU-T G.hn wired home networking standard. In May 2013 the HomePNA alliance merged with the HomeGrid Forum. So nowadays HomePNA and G.hn can perform similar functions.

Long-term product-lifecycle support for HomePNA seems to be somewhat questionable.

G.hn

G.hn is a specification for home networking with data rates up to 2 Gbit/s and operation over four types of legacy wires: telephone wiring, coaxial cables, power lines and plastic optical fiber. A single G.hn semiconductor device is able to network over any of the supported home wire types. G.hn was developed under the International Telecommunication Union’s Telecommunication Standardization sector (the ITU-T) and promoted by the HomeGrid Forum and several other organizations. ITU-T Recommendation (the ITU’s term for standard) G.9960, which received approval on October 9, 2009. The G.hn spectrum depends on the medium.

The G.hn2 specification was developed by the International Telecommunication Union (ITU). The physical layer is capable of supporting 10 Gbps over coax. It utilizes mesh technology, supports encryption on the cable, and supports distances up to 100 meters.

G.hn specifies a single physical layer based on fast Fourier transform (FFT) orthogonal frequency-division multiplexing (OFDM) modulation and low-density parity-check code (LDPC) forward error correction (FEC) code. G.hn includes the capability to notch specific frequency bands to avoid interference with amateur radio bands and other licensed radio services. G.hn includes mechanisms to avoid interference with legacy home networking technologies[6] and also with other wireline systems such as VDSL2 or other types of DSL used to access the home. Although most elements of G.hn are common for all three media supported by the standard (power lines, phone lines and coaxial cable), G.hn includes media-specific optimizations for each media: OFDM Carrier Spacing is 195.31 kHz in coaxial, 48.82 kHz in phone lines, 24.41 kHz in power lines. G.hn uses OFDM to achieve gross speeds up to 1 Gbit/s. The 5-200 MHz range handles upstream and downstream traffic using an Orthogonal Frequency-Division Multiplexing (OFDM) encoding. Transmission rates of 1 Gbit/s at application level are possible with coax cables up to approx. 800 meters, via phone line up to approx. 250 meters (MIMO) or approx. 150 meters (SISO). Connectivity up to approx. 1800 meters (coax) or 800 meters (phoneline) is possible.

G.hn is an access technology for operators looking to simplify their access network and reduce their costs with an Ethernet-like technology. The ITU-T G.9960 G.hn Wave-2 standard leverages the existing telephone wiring (UTP, CAT-3 or CAT 5/5e) or RG-6/RG-59 coax cabling (each coax port serves up to 16 subscribers) to deliver a gigabit Internet service to each apartment inside a Multi-Dwelling Unit (MDU) or Multi-Tenant Unit (MTU) without the cost, complexity, and delays, associated with in-building fiber installation. Each G.hn subscriber port supports up to 1.7 Gbps of dynamically allocated bandwidth for near-symmetrical gigabit services.

When operating over Coax, G.hn uses baseband spectrum from 5-200 MHz. Unlike Data Over Cable Service Interface Specifications (DOCSIS), G.hn dynamically allocates each tone to carry either upstream or downstream traffic to reflect the demand from the subscribers, achieving gigabit speeds in both directions.

Like the DOCSIS High-Split, G.hn allows CATV channels starting at 258 MHz. The very important difference and benefit of G.hn is that it does not use any spectrum that overlaps with the CATV content. It is very easy to overlay the G.hn and CATV signals over the same coaxial cabling using standard splitters-combiners. G.hn optimizes the spectrum use on coaxial cabling to achieve superior bandwidth to DOCSIS in the upstream and downstream directions.

The ITU-T G.hn standard provides high-speed (up to 1 Gigabit/s) local area networking over existing home wires, including coaxial cable, power lines and phone lines. It defines an Application Protocol Convergence (APC) layer for encapsulation standard 802.3 Ethernet frames into G.hn MAC Service Data Units (MSDUs). Because G.hn can operate over wires including AC and DC power lines, it can provide the communication infrastructure required for smart grid applications.

When G.hn devices has RJ11 connector for data communication and such device needs to be connected to coaxial cable, a suitable baluns is needed. Lea Networks Balun Media Converter, 75ohm Coax to 100ohm Twisted Pair, G.Fast & G.hn can convert balanced twisted pair signal to unbalanced 75Ω coaxial signal.

There is also a new faster variation G.hn2 coming. G.hn2 supports up to 10 Gbps over coax. Note that in order to achieve 10 Gbps, the entire coax RF spectrum is utilized so therefore the coax cannot be used with any other signals.

The Multimedia over Coax Alliance

MoCA Access™. provides managed services for symmetrical multi-gigabit, low-latency access over coax. Point-to-Multipoint Coax Connectivity. In short, MoCA delivers a reliable, wired home network connection over a home’s existing coaxial wiring, providing lower latency and near Gigabit speeds. With MoCA everyone in the house can stream 4K movies at the same time and enjoy super-fast speeds without lag or downtime.. MoCA promises to turn your Existing Cable Wiring into a 1 Gbps Super Highway. MoCA signals will not interfere with your existing cable modem and vice-versa, your cable modem will not interfere with your MoCA network. Using coaxial wiring replaces the need for installing Ethernet cabling throughout your home.

(MoCA) standard allows people to use TV-grade coaxial cable to carry modern ethernet traffic. You can get a MoCA bridge to use the cable from the wired ethernet. Some routers or TV based devices like TiVO have a MoCA bridge built in. If you don’t already have MoCA capable devices, you’d need to get a pair of MoCA bridges to connect devices over cable. There are MoCA adapters for creating Ethernet bridges over coaxial cable (while passing through CATV/OTA TV/CCTV/DOCSIS signals).

There has been several versions of MoCA. MoCA 1.0 was approved in 2006, MoCA 1.1 in April 2010, MoCA 2.0 in June 2010, and MoCA 2.5 in April 2016. The most recently released version of the standard, MoCA 2.5, supports speeds of up to 2.5 Gb/s. The Alliance currently has 45 members including pay TV operators, OEMs, CE manufacturers and IC vendors.

The technology started with Passive MoCA (with no active electrical components on integrated circuits) supports 10 Mbps. That was short lived experiment.

The first version of the standard, MoCA 1.0, was ratified in 2006 and supports transmission speeds of up to 135 Mb/s. MoCA 1.1 provides 175 Mbit/s net throughputs (275 Mbit/s PHY rate) and operates in the 500 to 1500 MHz frequency range. MoCA 2.0 offers actual throughputs (MAC rate) up to 1 Gbps. Operating frequency range is 500 to 1650 MHz. Packet error rate is 1 packet error in 100 million. In March 2017, SCTE/ISBE society and MoCA consortium began creating a new “standards operational practice” (SCTE 235) to provide MoCA 2.0 with DOCSIS 3.1 interoperability. Interoperability is necessary because both MoCA 2.0 and DOCSIS 3.1 may operate in the frequency range above 1 GHz. MoCA can operate up to 1500 1675 MHz.MoCA frequencies are 1125-1675MHz. Over-the-air TV frequencies only go up to 692 MHz.

MoCA 2.5 (introduced April 13, 2016) offers actual data rates up to 2.5 Gbit/s, continues to be backward compatible with MoCA 2.0 and MoCA 1.1. The current MoCA 2.5 Gbps devices utilize frequencies above 1 GHz to achieve 2.5 Gbps, thereby allowing normal cable signals below 1 GHz. Bonded MoCA 2.5 supports up to 2.5 Gbps in throughput, but as of early 2019, most adapters available use bonded MoCA 2.0 (1 Gbps) or lower. The largest vendors are Actiontec, TiVo (OEMing Actiontec), Teleste, and Yitong.

The MoCA 3.0 standard has been released and increases the maximum throughput to 10 Gbps. MoCA 3.0 specification utilizes mesh technology, supports encryption on the cable, and supports distances up to 100 meters. Note that in order to achieve 10 Gbps, the entire coax RF spectrum is utilized so therefore the coax cannot be used with any other signals. If less than 10 Gbps is utilized, then the RF spectrum could be shared. MoCA 3.0 is backwards compatible with MoCA 2.0 and MoCA 2.5.

Modern MoCA with active electronics is a mesh technology and you can have up to 16 nodes through your house. Most MoCA bridges work in the D band, above 1 GHz so they are compatible with cable TV signals. You can get bridges that support 1 Gbps (MoCA 2.0 profile C bonded channels). MoCA adapters multiplex and diplex Ethernet and any passed-through signals in the 7-42 MHz and 54-875 MHz range (such as TV, cable modem, etc.), so a minimum of 2 adapters are required to book-end the signals. With a MoCA adapter at point A and another at point Z, the network functions as though an Ethernet cable connected the 2 points. But again, it takes two to tango. (You can add 16 total adapters in many cases, but that merits a discussion about MoCA splitters and point-of-entry filters.) You also need to be concerned with port-to-port isolation. With satellite splitters, the port-to-port isolation in the MoCA bandwidth is a minimum 24dB, while with MoCA splitters, it is a maximum 25dB. With MoCA, you want the signals to be able to go from one port to another without too much obstruction.

Due to the isolation requirements for MoCA and DOCSIS to minimize interference, a two-box solution is preferred for HFC. This separates the home network from the outside plant. Additionally, this allows for the same home network architecture regardless of whether HFC or fiber is used for the access to the home.

MoCA videos:

Teardown of an ActionTec WCB3000N MoCA v1.1 Cable to Ethernet adapter
https://www.youtube.com/watch?v=6ye1xwWR3bM

Hacking a super cheap MoCA adapter to make it do my bidding! Ethernet over coaxial cable.
https://www.youtube.com/watch?v=hiNSjBW_UtA

How to Install a MoCA-Enabled Cable Modem to Improve Network Performance
https://www.youtube.com/watch?v=x0cgXY3Q_Zc

MoCA Setup and Testing
https://www.youtube.com/watch?v=t0h_Zag7cpU

Double your Home Network Speed – Motorola MOCA Adapter
https://www.youtube.com/watch?v=i9WVH-2BjDA

How to Turbo-Charge your Wi-Fi(R) with a Wire
https://www.youtube.com/watch?v=BMO7B0pzYjQ

DOCSIS

Coaxial Ports are used by cable operators for modems based on DOCSIS standard.Data Over Cable Service Interface Specification (DOCSIS) is an international telecommunications standard that permits the addition of high-bandwidth data transfer to an existing cable television (CATV) system. It is used by many cable television operators to provide cable Internet access over their existing hybrid fiber-coaxial (HFC) infrastructure.

The base definition of DOCSIS 3.1 allocates the 5-42 MHz range to upstream traffic, resulting in “up to” 100 Mbps of shared bandwidth across all subscribers on a Cable Modem Termination System (CMTS) port. DOCSIS vendors have recently introduced solutions to provide more upstream bandwidth by extending the spectrum for the upstream bands.

DOCSIS is technology designed for cable TV operators in mind. A DOCSIS modems are designed to always communicates with equipment that cable TV has in it’s network. You can’t make a home network with two DOCSIS cable modems only, you need the cable TV operator always “in the loop”.

Cable television (CATV) networks are governed by a set of DOCSIS standards that place hard limits on bandwidth and data rates. The latest version of the DOCSIS standard, DOCSIS 3.1 was released in October 2013. DOCSIS 3.1 increases the bandwidth and data throughput available in CATV networks by up to 10 Gbps downstream and 1 Gbps upstream.

Isemag article says on network engineering: A DOCSIS network is engineered to serve an average of 150 subscribers on the premises in which the peak use per subscriber is well below 5 Mbps downstream and below 350 Kbps (not Mbps) upstream. To me those numbers on data rate seem to be quite low, and maybe reflect to the old days then users did not need high bandwidth Internet.

Technologies for 10G networking

In 2019, the cable industry announced the 10G Initiative to bring 10 Gbps into customers’ homes. Once it gets to customers’ homes, how will it be distributed throughout the home?

There are four candidates that can meet 10 Gbps in a consumer home environment: Ethernet 10GBase-T, MoCA 3.0, hn2 (coax) and Wi-Fi 7.

For 10G delivery within the home, it is suggested that Ethernet 10GBase-T, MoCA 3.0, or G.hn2 (coax) be used for hardwire delivery of the 10 Gbps data within the home to Wi-Fi 7 access points (APs).

Cable operators need to start thinking about how they will distribute the 10 Gbps signal through the home network once 10 Gbps technology is available and offered as a service. If they desire to use Ethernet, then the use of coax in homes should be switched over to Ethernet. If they desire to utilize the existing wiring and continue to use coax, then they need to plan on utilizing MoCA 3.0 or G.hn2, and to start deploying it as soon as the desired technology is available. When Wi-Fi 7 is used for communication, multiple APs will be required to provide the desired speeds throughout the premises.