Cable topology

Snurg

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#26
I would strongly advise against using powerline.
At least if you have no detailed knowledge about your electric configuration topology. For example, there are still some 127V networks in some regions of Europe. The 220V you get from these are not true 220V to ground, instead this is the differential of two phases shifted 120 degrees, as PacketMan described. These have no real ground connection because the currents flow between two floating phases, and powerline will perform poorly because it has to go through the transformer and side channels like appliances. This will result in poor and inconstant performance, if it works at all.

Another possible problem results in that if your house is supplied with three phases, they could be distributed differently for load balancing. For example, if L1 supplies room A and L2 supplies room B, you won't get a powerline connection working (except maybe poor connection via side channels like three-phase appliances, heaters and the like ).

But the worst thing is that it can make heavy radio interferences, and if somebody complains about, say, bad radio reception, the local authorities can find where this comes from.
And if they find it's your powerline ethernet, you are responsible, and will have not only to pay a fine, but also get prohibited to use that again, possibly even getting your equipment confiscated.
Your local jusrisdiction might be slightly different, but afaik it's the same all over the world. If you are responsible, you have to pay.

This is the reason why there exist no such things which insert an additional networking band into a broadband cable. It would cause many issues, as it would inevitably distort the whole cable segment, causing much anger with people still using analog TV etc. This would be as punishable as causing distortions via RF emissions using powerline, as described above.

As SirDice said, coaxial ethernet is history, 10Base2, using RG58 or the like with 50 ohms impedance.
I had to maintain a big network of a German newspaper a quarter of a century ago. Total length of cabling was about a kilometer, with about 100 computers connected.
It was horrible task. So many possibilities for things to go wrong. And things went wrong often.
Bad terminations, weak connections, damages in the cables, defective network cards or MAUs. A single of these problems could put a whole segment of the network out of operation.
Luckily I had a specialized ethernet tester, showing problems like this, open connections, shorts, bad terminations etc and indicating the cable distance where the problem was.

When a problem occurred, I had to rush, as often dozens of journalists were waiting for me to find and fix the problem asap. This was quite stressy, as the premises were quite big.
For example, one day some plumbers drilled holes in the walls, and drilled into a cable. I had to hurriedly lay almost 100m temporary cabling through the stairways, connecting the remote floor to the servers again.

This I'd really suggest to lay an additional twisted pair ethernet cable. But, make sure to cut the grounding of the cable if your electric installation has no separate ground connection, which is often the case with older installations which have floating grounds.
 

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#27
One way you could try is to replace the existing 'old' coax cable. You tie a new coax cable and an UTP cable to one end of the existing coax cable. Then from the other side pull out the old cable. If done properly the attached UTP and new coax cable will be pulled into and through the piping. Not to be taken lightly, and it definitely helps if you've done this before. It takes a bit of fiddling to attach the new cables to the old in such a way they won't come off or get snagged somewhere half-way through.
 

Snurg

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#28
You could ask your local electrician. Pulling cables through cabling tubes as SirDice mentioned above is usually being done using glass fiber strings made exclusively for this purpose.
The electrician also can tell you whether it is advisable to cut the grounding from your ethernet cable (i.e. if you have floating ground).
 

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#29
Pulling cables through cabling tubes as SirDice mentioned above is usually being done using glass fiber strings made exclusively for this purpose.
Fibre usually gets "blown" into piping, it's called cable jetting. But both coax and UTP are usually sturdy enough to be pulled the traditional way.
 

usdmatt

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#30
We pull cables with pull wires (sometimes an existing or spare bit of cable) all the time. Gets a bit frustrating when you use enough tape an elephant couldn't pull it off, and yet the second the cable goes out of sight it slips free with the slighted tug.

If you're pulling multiple cables it helps to attach them staggered so that you're not trying to get all the cable through together. (attach one cable to the existing one, then attach the second to the new cable further down so there's no point with all 3 cables together) Another trick is to strip the cables back 6 inches, fold a couple of the inner conductors over each other and back on themselves, then twist the excess. You end up with a link that is pretty strong, and also get the benefit that the join is actually slimmer than the original cable. (The most common issue is that you usually have a bump where the new cable is attached to the existing, which gets caught on everything).

cut the grounding from your ethernet cable
Not sure what you're referring to here?
 

Snurg

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#31
Not sure what you're referring to here?
What I was referring to here is when the electric wiring is done with 2 wires only (one live, one ground), where the ground wire also gets connected to the earth connector in the wallplug.
In these cases you have sort of "floating earth".
Depending on the current, there is always a voltage drop along the wires.

For example, if there is a, say, 10amps load from an electric heater, then the earth connector on a 2-wire electric connection can get quite high voltage relative to actual ground level.
This is due to the wiring resistance causing voltage drop.
And now imagine a, say, ethernet cable connecting to another computer on another electric line, which has less load.
This is like a parallel circuit of resistances. The ethernet cable shielding will then serve as secondary ground wire, supplying a part of this load current.
Which it is neither intended nor rated for. Imagine that thin foil shielding and the thin ground wire of the CatX cables having to bear a current of, say, 5 amps... ...this is a serious fire hazard.

And, sadly these two-wire electric installations are not that rare.
Thus especially in buildings with older electric installations one should check this out to be on the safe side.

To make sure there is no fire hazard, it is advisable in such cases to strip off a segment of the cable screening, cutting the ground connection between both ends of the cable while maintaining most of the RF shielding.
The data lines are fed through insulation transformers usually rated to at least 1kV, so they will not serve as conductors (unless the cable is defective due to internal shorts).

(The above applies *only* to ethernet patch cables! The situation and the necessary protective measures are different with other kinds of interface.)

BTW, usdmatt, great collection of tricks for pulling cables. I even sometimes soldered the wires being pulled out with these to be pulled in, results in a quite strong connection without bump.

Edit: Regarding the ground issue, I found a detailed article covering other aspects of that topic, too.
 

ronaldlees

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#32
I remember pulling a 100' fish tape reel line through an outdoor conduit at 18 deg F, dragging a thick bundle of telco. The conduit was 175' in the air, on the side of a tower. It was "back and forth, back and forth" until our fingers were frozen. The run wasn't a straight shot either. Then we hoped there was no chafing, shorts, cursing, and redo (would have been the next day, for dang sure). House wiring? No prob.
 
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balanga

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#33
Whilst on the topic of cable, can anyone tell me if I can add my own TV decoder in another room or does it have to be one provided by my cable provider? I notice that the decoder I have does have an IP address so maybe they can block devices which do not have known MAC addresses...
 

usdmatt

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#34
Does the decoder have a private or real IP address? I'd expect the decoder to just use the Internet via the router rather than having its own connection. Your router appears to be a modem/router/firewall/ap so there's quite a few settings there you as an end user may want to change, so I'd be surprised if you aren't allowed access to it. There may be a section in the web interface showing connected devices which will tell you if the TV decoder is connected to it or not.

To be honest within 5 minutes of getting it, I'd have looked up the internal address of the router (default gateway in ipconfig/ netstat -rn), and be trying default logins in the browser to see what I can do (or looking on the router itself for a label with the login details).

Of course depending on how clever the ISP network is, they could be identifying the modem in the TV decoder and attaching that to a dedicated VLAN with a NAT gateway. I wouldn't want to put the TV boxes on real addresses. Seems over complicated to provide two connections when the decoder could just use WiFi though.
 

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#35
can anyone tell me if I can add my own TV decoder in another room or does it have to be one provided by my cable provider?
Your cable provider will be able to answer that. Some allow third-party decoders, some don't. And some will charge extra for each additional decoder.
 

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#36
I'd expect the decoder to just use the Internet via the router rather than having its own connection.
With Ziggo (Dutch digital cable provider) the decoder has an IP address but it's connected to a separate network, it does not 'share' the internet connection.
 
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balanga

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#37
Does the decoder have a private or real IP address? I'd expect the decoder to just use the Internet via the router rather than having its own connection. Your router appears to be a modem/router/firewall/ap so there's quite a few settings there you as an end user may want to change, so I'd be surprised if you aren't allowed access to it. There may be a section in the web interface showing connected devices which will tell you if the TV decoder is connected to it or not.
Unfortunately access to the router is not available. No login details are provided. This is the ISPs policy.
 
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