HomePlug FAQ *Part 2*

mickevh

Distinguished Member
The "point" of HomePlugs is that they provide an alternative to installing "proper" wired ethernet cabling by instead tunneling data over something already existing in most homes - ie the mains electricity circuit. Early on, HomePlugs didn't have Wi-Fi capabilities at all - some still don't.

Wi-Fi AP's were built in to HomePlugs later on for the purposes of extending Wi-Fi coverage. But there's no point in providing an AP in the HP connected to your router as that routers built in AP provides coverage in that locale.

Technically (if the "right" kit were designed) you could create an HP infrastructure where the "first hop" to the rest of the (wired) network was achieved using Wi-Fi, but that's such a rare use case and so doing would have serious consequences for Wi-Fi throughput ("speed") most don't bother.

It's kind of a "why would you bother" argument: If you are going to use the mains electricity circuit to transmit data, your router is plugged into said mains (ie there's a mains socket near your router) "why would you bother" making a Wi-Fi link to your router when the infrastructure to make a wired link is already in situ and a wired link will be faster and more reliable and "free up" some Wi-Fi air time.
 

shackec

Member
The "point" of HomePlugs is that they provide an alternative to installing "proper" wired ethernet cabling by instead tunneling data over something already existing in most homes - ie the mains electricity circuit. Early on, HomePlugs didn't have Wi-Fi capabilities at all - some still don't.

Wi-Fi AP's were built in to HomePlugs later on for the purposes of extending Wi-Fi coverage. But there's no point in providing an AP in the HP connected to your router as that routers built in AP provides coverage in that locale.

Technically (if the "right" kit were designed) you could create an HP infrastructure where the "first hop" to the rest of the (wired) network was achieved using Wi-Fi, but that's such a rare use case and so doing would have serious consequences for Wi-Fi throughput ("speed") most don't bother.

It's kind of a "why would you bother" argument: If you are going to use the mains electricity circuit to transmit data, your router is plugged into said mains (ie there's a mains socket near your router) "why would you bother" making a Wi-Fi link to your router when the infrastructure to make a wired link is already in situ and a wired link will be faster and more reliable and "free up" some Wi-Fi air time.
Thank you for your response. I understand the broad principles involved. But I was more concerned with understanding the mechanics as it were. I assume that the router isn't sending the internet data down to the mains plug and into my electrical wiring. The router is connected by means of an ethernet cable to the adapter which is plugged into the electrical system. From there the internet data is circulated through the electrical system to the two extenders that I have in further parts of the house. I assume the router somehow recognises the adaptor and passes internet data to it. The adapter then sends a signal through the wiring system. This means that I have an ethernet cable permanently linking my router to the adapter. This s not a problem but it is just one more wire to add to the plethora of wires tangled up behind my router! It could be that later models of the adapter have a wireless capability which would eliminate the ned for an ethernet cable? That would be nice, not essential, but convenient.
Now I just need to understand how the security aspects of the system works and I will be happy!
Thank you for your interest and help. Regards Charles
 

mickevh

Distinguished Member
Thank you for your response. I understand the broad principles involved. But I was more concerned with understanding the mechanics as it were. I assume that the router isn't sending the internet data down to the mains plug and into my electrical wiring. The router is connected by means of an ethernet cable to the adapter which is plugged into the electrical system. From there the internet data is circulated through the electrical system to the two extenders that I have in further parts of the house.

More or less. Data travels around in discrete little units called packets, like letters in the post. The packets have a kind of envelope with addressing information written on them and some content (usually called the payload in data networking.) Devices such as as routers, switches, AP's, HomePlugs and so on are like the sorting offices. They process the packets one by one forwarding them towards the intended destination based on the addressing. The mechanisms of "switching" and "routing" are different in detail, but for the purpose of this discussion, just accept they are both packet switching paradigms.

I assume the router somehow recognises the adaptor and passes internet data to it.

In LAN's nothing is "in charge" of the network and nothing needs to have "knowledge" of anything else. Devices will accrue knowledge that allows them to make appropriate packet forwarding decisions. Your router for example, (or more correctly the switch built into your router - the "LAN" ports) learn which devices can be reaches through which port based on their addresses. Thusly, to despatch a packet the router doesn't need to "know" what is connected downstream of it, it only needs to know that (for example) to forward a packet to device X it needs to be despatched through port Y. Just like the posties in the sorting office don't need to have a map of the UK in their heads, they only need to know that packets addressed to London despatch through door number 1, packets addressed to Glasgow despatch through door number 3 and so on.

The adapter then sends a signal through the wiring system. This means that I have an ethernet cable permanently linking my router to the adapter. This s not a problem but it is just one more wire to add to the plethora of wires tangled up behind my router! It could be that later models of the adapter have a wireless capability which would eliminate the ned for an ethernet cable? That would be nice, not essential, but convenient.

There are routers with HomePlugs built in, but it's rare. As discussed above, the concept of a Wi-Fi based router-HomePlug link is moot - it really is pointless and has more detrimental effects than positive ones so I wouldn't hold out hope for it.

Now I just need to understand how the security aspects of the system works and I will be happy!
Thank you for your interest and help. Regards Charles

I believe HomePlugs use encryption that ensure any signals straying down the wires beyond your home cannot be read by (for example) a neighbour. Wi-Fi is also almost always encrypted these days. It generally just a matter of picking which encryption is used, the choosing a passphrase (or "Wi-Fi key") which is used to seed the encryption key used. The encryption employed by HomePlugs (between each other over the mains) and by Wi-Fi (over the radio waves) are distinct and separate. Ethernet is usually unencrypted.
 
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shackec

Member
Thank you for your response; it has helped me to fill in some gaps in my understanding. I think I now need to dig into how my router works a little more deeply. Having "logged" into the router through my web browser I am confronted with a network map which shews the connection status of all the devices connected to my router. Very useful. However, the router is shewn linked to two branches. One branch shews my two mobile telephones and a tablet each with an "halo" of blue radiating lines. Presumably meaning that they are in connection with something. The other branch shews icons for my mac and ipad and these do not have blue "halo"s. Presumably not connected to something. However all devices seem to be connected to the internet in a satisfactory manner!
You wouldn't happen to have any idea what this means?
My router is an Zyxel and I attach a screen shot shewing the network map.
Regards Charles
 

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mickevh

Distinguished Member
These sort of maps are entirely for the convenience of human beings and are not fundamental to how your router "works," so don't worry that things you know are Wi-Fi devices are depicted as "wired." It's showing you what it's talking to over "wires" and what it's talking to over "Wi-Fi."

Here's how it works:

Looking at the work from your routers perspective, all it "knows" about is whether traffic enters through it's Wi-Fi antenna or one of it's LAN ports. It has no way to discover what else is beyond it's own horizon (and has no need of such knowledge.)

When the postman knocks on my door and delivers a package, all I "know" is the package entered through my front door (and not the back door.) I've no idea what route it traveled to reach me, what sorting offices it passed through or what modes of conveyance were used. And I don't care - it's of no relevance to me; the package got delivered and that's all that matters. As far as I know, China, India and the UK all deliver through my front door. My sisters kids deliver through my back door.

Same for your router; it doesn't know (or care) what HomePlugs, Wi-Fi APs, switches or anything else are connected up/downstream of it. For example, if we had a Wi-Fi AP connected to one of the routers LAN ports and a client connected to said Wi-Fi AP, the traffic from client to router has traveled client~~~AP over Wi-Fi and AP---router over ethernet. (The AP converts it from Wi-Fi format to ethernet format and vice-versa.) As far as your router is concerned, it sees traffic from endstation X arrive on an ethernet port, so it's "wired." So you see the seemingly bizarre situation that (for example) your iPad is reported as a "wired" device. It's because the router saw the traffic from that device arrive on one of it's (wired) LAN ports and not through it's Wi-Fi antenna.

As vendors realise that more and more people have home networks that consist of more than "just the router" they may start to drop this particular "dog a pony show" in the router user interface.
 
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shackec

Member
Thank you, that is very reassuring. It also explains why the "map" has two branches; one for the wifi devices and the other for the etherenet devices. That is to say it explains why one branch has those wavy blue lines!

It obviously doesn't matter but I am curious as to why my mac and ipad suddenly got reassigned to the ethernet branch. They were on the wifi branch yesterday and today they are on the ethernet branch. And I have nothing plugged into any of the ethernet ports on the router. These machines seem to have a mind of their own! Thanks again for the explanation,. regards Charles
 

mickevh

Distinguished Member
Presuming they are both Wi-Fi devices, they are not "assigned" which AP they "connect" to (called "Associate" in Wi-Fi speak) - at least not in SOHO kit, in big boys enterprise systems, sometimes the system administrator can control it if the kit has the capabilities.

It is the client devices themselves that decide which AP to Associate with and if/when to "roam" between them. It's probably easiest to illustrate this by following though the sequence of events when you power a client up: I'm making up this example as none of this is prescribed by standards: Client will listen listen out for what's advertising, if it sees an SSID it's used before, it'll check out which AP's are advertising that SSID, pick one and Associate with it. There's nothing prescribed in standards as to what algorithm a client uses to choose an AP, so it's essentially up to the client equipment designer. For example, it might choose the AP that responds first, the one with the loudest "signal," the one with the lowest signal-to-noise-ratio (SNR,) the fastest advertised "speed" or something else. As users, we have little if any control over this.

It's similar with roaming determination - there's a popular myth that clients are always "hunting for the best signal" but they do not and some need the incumbent to get pretty grotty before they initiate a roaming assessment. Again, as users we have pretty much no control over this and we are in the hands of the client designers, but I have seen clients that offered a bit of control over (for example) favouring a particular waveband, protocol, or a "roaming aggressiveness" control.

As Wi-Fi standards have evolved a mechanism has been designed whereby an AP can send a kind of "hint" to a client that it might do better with a different AP to try and encourage them to roam sooner. Of course, that requires clients that are "hint compliant" and even then they don't have to "take the hint." However, this hint mechanism requires a system of AP's that "talk" to each other to share information about which can hear which client the best, which is most heavily loaded and so on. Again, enterprise systems tend to be first out the traps with this kind of thing, but I suspect (not that I've checked) it's something that is increasingly included in the so-called "mesh" and "whole home" type systems. Of course, that locks you in to buying all your Wi-Fi AP's from the same manufacturer, possibly even the same product range.
 

shackec

Member
Now, that is very interesting and would completely explain, what appears to be, the erratic nature of my systems behaviour. It also means that I do not have an underlying problem with the system organisation and I can relax!
With this information I suspect with a little manipulation i could probably get all my devices to appear as wireless ones, Although, as you have explained, there is little point. Thank you so much for your help with this. Kind regards Charles
 

shackec

Member
The next chapter in my saga! I linked my Tp-link adapter (plugged into the mains), by ethernet cable, to my router. I then plugged in an extender (fairly nearby but I don't think that's important). I used the tp-link utility programme to set the router SSID and passkey in the extender; to match the router. Hey Presto, the extender appeared in the network map of my router. In the branch for ethernet connection.

But, the extender does not appear as a wi-fi source in any of my devices! In fact my tablet was helpful in saying that it could not connect because of an "authentication" issue. Isn't it odd; the router has identified the extender but cannot pass data to or from it to my devices.
I router appears to be on channel 1; although I think it is set at automatic. The extender is set on channel 6.
 

tom 2000

Distinguished Member
What happens if you give the extender its own SSID and password?
 

mickevh

Distinguished Member
If the SSID's are the same, Wi-Fi client devices won't list the all the AP's separately: Wi-Fi clients list all the different SSID's they can hear, not all the AP's.

If you contemplate a site with dozens/hundreds of AP's, users wouldn't want to be bothered choosing which one they want to use, so clients only list the different SSID's and the automation in the clients decides which one to use and when to roam between them.

I am not surprised your router map lists the AP as a wired device as as far as it's concerned it is. The router doesn't know or care what it's capable of, all it know is it's seen some traffic from device X arriving on a wired LAN port. (The traffic in question is almost certainly the traffic from the admin interface.)

It is best to have the cells on different radio channels so they do not interfere with each other. In small SOHO LAN's I would set it myself and not let it "auto-tune" as in a heterogenious equipment mix the AP's could end up enlessly retuning to "avoid" each other. In the 2.4GHz waveband choose channels from the set [1,6,11] in the 5GHz waveband (if you have it) just ensure the channels are different.

Again, your router couldn't care less what's happening downstream of it. There's not some sort of "magic dust" that your router needs to sprinkle of the AP's in the network in order for them to "work." Your AP's are completely "self contained" stand alone devices. All they need is a link to the rest of the network.
 
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Hixs

Distinguished Member
Are the advertised ethernet speeds of these home plugs generally what they offer up in real usage?

I just had 2Gbps fiber installed today so looking maximize its potential. Connecting via traditional ethernet isnt possible due to location of box, age of property (2ft solid walls) and size (450sqm over 3 floors).

Probably run some sort of mesh system for general WiFi use as the livebox doesn't extend very far into the house due to wall thickness I'm thinking more download speeds for my PC/Xbox etc

I'm not very clued up on this subject, so be kind!
 

Greg Hook

Moderator & Reviewer
Are the advertised ethernet speeds of these home plugs generally what they offer up in real usage?

I just had 2Gbps fiber installed today so looking maximize its potential. Connecting via traditional ethernet isnt possible due to location of box, age of property (2ft solid walls) and size (450sqm over 3 floors).

Probably run some sort of mesh system for general WiFi use as the livebox doesn't extend very far into the house due to wall thickness I'm thinking more download speeds for my PC/Xbox etc

I'm not very clued up on this subject, so be kind!
No, they are not anywhere near the real world usage.

Say they advertise 1000Mbps, that's immediately half as they quote the upstream and downstream.
So the very best you will get under lab conditions is 500Mbps. In reality that would be significantly less.

When I used to review these I vaguely recall that 1000Mbps would get me at best around 250-300Mbps. The 500Mbps sets would be about 80-100.
 

Hixs

Distinguished Member
Damn. Better then WiFi mind. Laptop only has a 100Gbps card in it. Speedtest showed it pulling 90 on average. Upload is down to 15ish though which is poor considering a supertest at the modem shows an upload of 600Mbps+.

Maybe a better WiFi card?
 

mickevh

Distinguished Member
Different data networking technologies have different operating paradigms which means they are not directly comparable. Thusly one would not expect 1000mbps HomePlugs (even if they actually sync up at that speed) to be anything like as "fast" as 1000mbps ethernet. (Same for Wi-Fi incidentally.)

In much the same way that you wouldn't expect a sport car and a bus to convey the same amount of people per minute just because they both could proceed down the road at the same "speed." So just because lots of things cite some "bits per second" it doesn't mean you can expect them to perform similarly just because the number matches up - it's way more complex than that.

In data networks, each "hop" in the network functions independently of all others. The "black art" of network planning is that one needs to be aware of all the technologies employed and how they effect throughput (not to mention you have to estimate the effects of traffic levels and flows) to try and predict the performance of any given pathway between any two given endpoints.

Homeplug type technology is not particularly efficient. Wi-Fi is a bit better, but not much. However, much is dependent on your use case and other conditions of the locale they have to piggy back onto wherever they are deployed. If you want fast reliable data networking, then ethernet is still the best - if speed "really" mattered, one wouldn't bother with HomePlugs or Wi-Fi.

If you want to get into the networking "numbers game," then you'll need to (metaphorically) go back to school and learn your data networking ABC's to understand what's up - just comparing the "bits per second" numbers of different technologies is unhelpful - almost meaningless - and could lead you to buy stuff you don't really need and/or not understand why shiny new toy X "isn't as fast as it says it is."

A lot of newbies and amateurs really tie themselves in knots "worrying" about this kind of thing. Just try it when you get it - if it's fast enough, don't worry about it. If it isn't, they try and fix it. By way of exemplar, I haven't got a clue how fast my broadband is - it was something like 43mbps when they put it in and I know is been increased a few times, not that it's made any difference to my usage experience 'cos it's always been "fast enough for me."
 
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oneman

Well-known Member
Damn. Better then WiFi mind. Laptop only has a 100Gbps card in it. Speedtest showed it pulling 90 on average. Upload is down to 15ish though which is poor considering a supertest at the modem shows an upload of 600Mbps+.

Maybe a better WiFi card?
You wiring will have a big impact on speed, figures quoted are for ideal conditions.
 

Hixs

Distinguished Member
98% of the wiring in the house is reasonably new. Anywhere from 6 months to 7 years old (full house renovation). There is only a few untouched plugs remaining from the previous owner. Consumer board was replaced in 2014/15.
 

mickevh

Distinguished Member
The "newness" of the wiring is not any kind of predictor when it comes to HomePlug/powerline. One has to consider the environment holistically and there's lots of pitfalls.

Some examples:

The sparkie that installed the twin and earth mains wiring wasn't doing so in mind of it's future use for data networking, so there may be kinks and/or knots in the cable runs that set up all sorts of standing waves, reflections and other horrors which my electrical engineering colleagues will understand much better than me, but are the enemy of high frequency signal propagation.

"Other" things connected to the mains may be introducing signals onto the mains that interfere with the HomePlug signals - dimmer switches and noisy transformers are often cited - and lots of things cause glitches when they switch in and out (fridges, central heating, washing machines, showers, etc. etc.) It's not just about "the wiring."

Mains wiring is (usually) not shielding at all from radio interference. (Ironically, radio hamms often complain about the amount of RF noise HomePlugs create!) So could be acting as antenna for anything in the area.

As with so many engineering and IT systems, we cannot "just assume" things based on what we want to believe. To "know" we'd need to strap on all sorts of oscilloscopes and expertise and see what is actually happening in any given use case.

There is no adequately good predictor of how any HomePlug deployment is going to work - you just have to suck it and see. Received wisdom seems to be to procure HomePlugs from somewhere with a good returns policy in case they don't work out.
 
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oneman

Well-known Member
You have to remember that mains wiring was never designed to carry a data signal, the fact it works at all is almost an electrical miracle.
 

Stuart Wright

AVForums Founder
Staff member
Howdy folks.
We have just had BT full fibre connected and with my phone (iphone Xs), I am getting about 350 down and 50 up. The Netgear 1000 home plugs (one right next to the router in the hall and one next to my PC in an adjacent room) are giving me about 50 down and 40 up.

The router is about 20 feet from my PC but still not convenient to run a network cable. Should I ditch the home plugs and get a Wi-Fi PCIe card for my computer?
 
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Hixs

Distinguished Member
Your phone has a good WiFi chip. I have 2Gpbs fiber and my phone only gets 50Mbps(5g) with a full signal.

My laptop is also connected by WiFi and pulls around 300Mbps max. Guess that's the WiFi card maxed.

For the price of a WiFi network card it's worth a try.
 

Stuart Wright

AVForums Founder
Staff member
Your phone has a good WiFi chip. I have 2Gpbs fiber and my phone only gets 50Mbps(5g) with a full signal.

My laptop is also connected by WiFi and pulls around 300Mbps max. Guess that's the WiFi card maxed.

For the price of a WiFi network card it's worth a try.
It's an iPhone Xs. Have edited my post to add that info.
Was looking at
Amazon product
 

jj2005

Standard Member
I'm looking for a powerline Wi-Fi extender for a wired laptop and wireless speakers, tv and tablet for an attic conversion.
Would both of these do the job?
TP-LINK WPA4220 AV600
Tenda PH5 AV1000

If so, is there either which you'd recommend over the other?
 

mickevh

Distinguished Member
It's probably going to be difficult for anyone to offer a simple yes/no recommendation as there's so many variables involved that are unpredictable. For example, "it depends" on how much data you are moving, what applications you are using, (which informs the data volumes,) and what rate HomePlugs actually work at in your locale which is highly dependent on the quality of your wiring and how electrically "noisey" all the other devices are which effects the speeds.

Received wisdom on HomePlugs seems to be to buy the fastest you are prepared to pay for from somewhere with a good returns policy in case when you get them home and try them out, the data rates suck in your locale.

Of course, like all Wi-Fi devices, there are now multiple protocols available so you'd perhaps want to check that you prospective purchase matched the Wi-Fi capabilities (A/B/G/N/AC) of your client devices - or to think of it the "other way around" not pay for something you don't need. Viz: no point pating a price premium for AC compatibility is you don't have any AC clients and don't expect to be acquiring any soon.

Bear in mind for Wi-Fi enabled HomePlugs there's multiple "speeds" to "worry" about - the speed of the ethernet ports, the speed of their Wi-Fi and the speed over the mains - each are separate and unrelated, but the each play a part in the usage experience (ie what you'll see if you run a "speedtest.")
 

Ged

Active Member
My limited knowledge but user experience of homeplugs is that they behave quite uniquely for no specific reason. Also, dodgy PSU can create interference which isn't something you may associate to WiFi networks.
I've had several network set ups and the most robust has been my current Netgear Orbi RBR20 with a switch on both..
Just my experience..
 

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