It doesn't happen often but in this case, I'm afraid RobertoS is talking nonsense, the VDSL socket is certainly not an ethernet interface, however the BT modem output is and this can be connected to the router via Homeplugs as the OP has done successfully.

It doesn't happen often but in this case, I'm afraid RobertoS is talking nonsense

You could of course have signed in, and then stated he was mistaken.

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In reply to a post by mrnelster:

It doesn't happen often but in this case, I'm afraid RobertoS is talking nonsense

You could of course have signed in, and then stated he was mistaken.

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But that would mean he does not need to PM everyone trying to find out who posted ...

Earlier I suggested to the OP he might be able to connect a Homeplug direct to the VDSL2 socket, then the modem upstairs where he has the hub.

Is that feasible, or nonsense? I was working on the premise that the output from the socket is Ethernet.

You must not have had your Weetabix that morning!

Homeplug between modem & router should be fine (badwidth apart), definitely not between faceplate & modem (that link just carries the VDSL signal, not ethernet frames).

Edited by mr_bean (Fri 13-May-11 14:01:34)

But the VDSL signal contains Ethernet frames.

Does anyone here know powerline adapters work anyway? Are they anything to do with ethernet other than that their sockets are designed to take RJ-45 plugs?

I'd still like to see what happens if it is tried.

(Edit - a little bit of googling seems to show that powerline technologyprotocol is nothing to do with ethernet, just transmission of the received signal. In which case there is a distinct possibility it would work).

Edited by RobertoS (Sat 14-May-11 16:07:37)

In reply to a post by Anonymous:

It doesn't happen often but in this case, I'm afraid RobertoS is talking nonsense ....

Moi?

In reply to a post by RobertoS:

But the VDSL signal contains Ethernet frames.

Not really.

It contains a series of "tones" over a range of frequencies that, when amplified, decoded and rearranged (particularly if interleave is on) can be assembled into Ethernet frames... not at all the same thing!

(Edit - a little bit of googling seems to show that powerline technologyprotocol is nothing to do with ethernet, just transmission of the received signal. In which case there is a distinct possibility it would work).

Virtually no possibility at all... it's possible the signals sent down the mains are akin to VDSL or ADSL tones, but the point of the adapter is to convert Ethernet to and from those signals. Just as the VDSL modem does for the phone line, but those signals are nothing like Ethernet...

In reply to a post by billford:

In reply to a post by RobertoS:

But the VDSL signal contains Ethernet frames.

Not really.

It contains a series of "tones" over a range of frequencies that, when amplified, decoded and rearranged (particularly if interleave is on) can be assembled into Ethernet frames... not at all the same thing!

I believe you Bill, but can you give me a source for that, as I spent an age seaching before posting that and found nothing really useful.

(Edit - a little bit of googling seems to show that powerline technologyprotocol is nothing to do with ethernet, just transmission of the received signal. In which case there is a distinct possibility it would work).

Virtually no possibility at all... it's possible the signals sent down the mains are akin to VDSL or ADSL tones, but the point of the adapter is to convert Ethernet to and from those signals. Just as the VDSL modem does for the phone line, but those signals are nothing like Ethernet...

Similarly, the nearest I got to how powerline adapters work was "orthogonal multiplexing", but no mention of the incoming signal needing to be ethernet. So anywhere I can read up for more detail please?

In reply to a post by RobertoS:

I believe you Bill, but can you give me a source for that, as I spent an age seaching before posting that and found nothing really useful.
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Similarly, the nearest I got to how powerline adapters work was "orthogonal multiplexing", but no mention of the incoming signal needing to be ethernet. So anywhere I can read up for more detail please?

You really need someone with a better understanding than I have of what goes on at the bottom levels of the OSI model, but here's my take on it.

First, I put the word "tones" in quotes to indicate that it's an analog frequency based system (though a bit more advanced than the acoustic couplers of days gone by!). More here, though it probably won't tell you anything you don't already know.

Second, the word "Ethernet" has more than one meaning:

It defines a number of wiring and signaling standards for the Physical Layer of the standard networking model as well as a common addressing format and a variety of Medium Access Control procedures at the lower part of the Data Link Layer.

My bold.

So at the data level, the outputs from NICs, routers, Ethernet homeplugs (into the mains) and broadband modems (into the phone line) follow Ethernet standards and protocols, so in that sense you were right- they all carry Ethernet data. But at the physical layer of the OSI model that's almost irrelevant- it's how that data is carried that matters, and the signal levels present at a network RJ45 connector are nothing like those that are suitable for putting down a phone line!

(Homeplugs and BB modems both use Orthogonal frequency-division multiplexing by the way, but that's more of a mathematical technique for handling the data than having anything to do with the data itself)

But there are also several physical manifestations of Ethernet- thick (co-ax), thin (co-ax), fibre-optic (one fibre for each direction), the twisted pair (one pair for each direction) that we all know and love and probably others I've forgotten about. These all use different voltage levels etc and so (even ignoring the different connectors) you can't just connect one to another and expect it to work. Similarly for a phone jack and a homeplug.

Homeplugs and broadband modems both do similar things- they convert the digital networking signals into a form that is more suitable for transmission down the chosen physical link (and convert the signals coming the other way of course). But because they serve different requirements, they have different electrical characteristics and so aren't compatible either with each other or the "original" signal they are carrying.

I'll be honest- I'm not all that happy with the above, it rambles a bit . But I'm just an electrical engineer not a networking expert, and I hope it makes some things a bit clearer.

Edited by billford (Sun 15-May-11 12:41:10)

I have not read the whole thread so forgive me if I have the wrong end of the stick. Do you propose to use mains adaptors to connect the VDSL modem to the faceplate fliter?
Apart from this probably being against BT T&C, (all modems and router/modems have seperate power supplies to reduce the chance of mains finding it's way into the phone network) the VDSL signal may well get lost in the general mush produced by them.