Cable topology

balanga

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#1
I'm moving to a cable ISP from fibre optics and am a bit confused as to how I can make the most of it... Basically the property has a single cable coming into the property and has a splitter feeding cables into two rooms. One has a TV decoder, the other has a cable router supplied by the ISP. I'm not sure if I can do anything with that router - I don't have login details and am not sure if I would break something if I tried resetting it. I would like to have a wired network in the room with the TV but don't know if that is achievable. I see that the TV decoder has been assigned an IP address so it has Internet access and I'm wondering what would happen if I added my own cable router... would it get an IP address from the ISP? Is there any way I can connect up the two rooms?
 

SirDice

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#2
The TV signal is usually out-of-band, i.e. it's not on the same network as your internet connection.

Most of the time you get a normal ethernet cable connection. Plug that into a router or a FreeBSD machine. Then on the other side of that router you can build a LAN just like normal. There's really nothing different compared to a cable modem/router except the way you're actually connected (fibre instead of cable).
 
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balanga

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#3
I guess I didn't express myself clearly... I have a cable from the ISP coming into the house to which there are cables to two rooms connected via a splitter. An ISP supplied cable router is connected to one of the cables in one room. Apart from using a Cat 5 cable how can I get connected a wired connection in the other room. If I installed my own cable modem would that connect to the ISP and auto configure itself?
 

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#4
For starters, you don't use a cable modem (or router). It's specifically for cable networks (DOCSIS). Fibre networks don't use DOCSIS so a cable modem is useless.
 

PacketMan

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#5
The signals on the coax cable are in different frequency bands, no different than radio stations in the air. So you cannot mess your TV by screwing with modems. The splitter simply puts all of the signals on multiple cables; there is no difference in the signals except the power level will be lower. Split too many times and the signals will be too low to use.

To use the ISP supplied modem/router simply put into the LAN port, and you should be able to use DHCP. NOTE: if its a modem and not a router you will get a public IP address, and you will need to supply your own NAT/firewall based router. If indeed its a router (both functions can co-exist inside the same device) then you should see that you have a private IP address.

Regarding having a 'LAN' in your place, over the coax wires, the only real way to achieve this is by using what is called a MoCA modem. I have three of these in my house and they work great. I use existing coax and attached three MoCA modems. The coax cables from units #2 and #3 go back to #1. At the #1 unit there is a splitter. I get approx 600Mbps of Ethernet throughput over the coax; not to shabby. Now for some important notes: I used coax that did not have TV signals on them, but I understand MoCA will work fine co-existing with TV signals because it uses different RF band. Also you can't assume the signals flowing in your house / apartment. As well, for the benefit of others, if you are in an apartment building, you have to be sure any and all cables are inside your place and in your control otherwise you have a security issue. Assuming you are good to go there, then generally speaking your topology should look like this:

Cable ISP modem >> NAT router >> Ethernet connections >> MoCA modem#1 >> coax cable >> MoCA modem#2 >> Ethernet connection.
To use a 3rd MoCA modem: MoCA modem #1 >> coax splitter >> MoCA modem #3 >> Ethernet connection.

This is really the only way you can use existing coax cable to build you own home LAN. Using additional cable modems will not work, unless the ISP offers such a service where they have their modems configured in such a way. I do know newer version of DOCSIS does provide L2 bridging services/functionality to modems, but I have yet to hear of an ISP providing LAN services inside a house using multiple modems.

Hope this helps.
 
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balanga

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#6
Thanks PacketMan - far more information than I can handle, but I'll keep reading it over - some of it may sink it :)....

This is the supplied ISP modem:-

http://www.normann-engineering.com/products/product_pdf/premise_equipment//technicolor/tc7230.pdf

I'm unable to log into it and was wondering what would happen if I did a reset, but maybe I would be unable to reconfigure it.
I guess my best option of having a wired network in the other room would be to use a powerline extender, if you don't think I can install my own router
 

ronaldlees

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#7
Thanks PacketMan - far more information than I can handle, but I'll keep reading it over - some of it may sink it :)....

This is the supplied ISP modem:-

http://www.normann-engineering.com/products/product_pdf/premise_equipment//technicolor/tc7230.pdf

I'm unable to log into it and was wondering what would happen if I did a reset, but maybe I would be unable to reconfigure it.
I guess my best option of having a wired network in the other room would be to use a powerline extender, if you don't think I can install my own router
Moca devices are really expensive. So, if you're on a budget, there's the passive devices. I've never tried them, and don't know if they really work - but do a search for "Passive Ethernet Extender for Coax" and you should find some of them, which are about the price of a WiFi dongle.
 

usdmatt

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#8
I would save the hassle and just run ethernet over powerline.

I know nothing about cable but would there be any possibility of removing the splitter, directly joining the incoming cable with the cable to the tv room (ideally using a junction box made for the purpose), then just re-using the splitter in the tv room to give you both tv & modem/router in that room?
 

PacketMan

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#9
Why not call the ISP, ask them what that devices does (i.e modem and/or router)? Why try to sneak around them? And ask them if there is a user interface that you can have access to? I know lots of ISPs that provide a router will provide access to the 'user' menus.

I tried powerline extenders, and generally speaking it sucks and I don't use them. Low bandwidth capabilities, and generally low performance / stability. Depending on where you live will affect the wiring in your building. In North America, our homes are wired twice. There are two 'hot wires', not one. Each hot wire is 120VAC, but each is opposite in the sine-wave cycle (some say 180 degrees out of phase but that is not technically correct) thus giving you the 220VAC for your stove, clothes dryer, and other heavy load appliances. What does this mean to powerline extenders? What this means is if you plug one extender into an outlet on "side A" and another extender into an outlet on "side B" there is no way for them to communicate directly, since the two sides two not touch each other directly. Thus there are only two 'paths' for the powerline signals to reach each other: (1) through the power company transformer that feeds your (and your neighbor) house, and (b) through the appliances I just mention. The transformers is a huge inductive/magnetic device, and the the appliances in your house have huge resistance currents going through them, so very harsh and 'unfriendly' to powerline signals. Unless your two outlets are on the same 'side' and wired on short runs, the performance is generally disappointing.
 
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balanga

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#10
Moca devices are really expensive. So, if you're on a budget, there's the passive devices. I've never tried them, and don't know if they really work - but do a search for "Passive Ethernet Extender for Coax" and you should find some of them, which are about the price of a WiFi dongle.
Thanks for pointing them out - I didn't know such things existed, but they did not see as cheap as you suggested.

Is this what you mean?
 

ronaldlees

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#11
Thanks for pointing them out - I didn't know such things existed, but they did not see as cheap as you suggested.

Is this what you mean?
I've never seen those, but they're not passive. They require a power supply. But - they're somewhat interesting I think. Thanks for the link!

I have no idea how they're set up - maybe they use a MC10EL89 "differential fan-out to coax" chip, or something like that, which is probably a lot cheaper than what the MoCA devices use ...

Would like to know.
 
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balanga

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#12
I would save the hassle and just run ethernet over powerline.

I know nothing about cable but would there be any possibility of removing the splitter, directly joining the incoming cable with the cable to the tv room (ideally using a junction box made for the purpose), then just re-using the splitter in the tv room to give you both tv & modem/router in that room?
er
What I wanted was wired Internet access in both rooms. Ethernet over powerline is probably my best option....

One thing which puzzles me is that these devises are rated at, say 500Mpbs, but if you have a computer with a 1Gb NIC and it connects to a router over a powerline connector the link speed will only be 100Mbps... or have I got that wrong?
 

usdmatt

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#13
Sorry, I wasn't sure whether you specifically needed Ethernet in both rooms, or had a need for Ethernet in the same room as the TV but could get away with wifi where the router currently is.

The speed you get is heavily dependent on the quality of the wiring and distance between the units. Just like the speeds quoted for WiFi it's usually impossible to get the full speed, unless you literally just connect the transceiver chips in each unit directly with a dedicated cable and get their absolute maximum rated performance. I also suspect many of them, again like Wifi, have a tendency to quote overall capacity (both ways added together) rather than actual link speed. (For instance you can buy wireless gear that says 1200Mbps!!, but really it tops out at 600Mbps if you actually want to use it full duplex.)
 
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balanga

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#14
I've never seen those, but they're not passive. They require a power supply. But - they're somewhat interesting I think. Thanks for the link!

I have no idea how they're set up - maybe they use a MC10EL89 "differential fan-out to coax" chip, or something like that, which is probably a lot cheaper than what the MoCA devices use ...

Would like to know.
I'm even more confused because this looks very similar to the above but is described as a MoCA adapter
 

ronaldlees

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#15
I'm even more confused because this looks very similar to the above but is described as a MoCA adapter
Yes, that's a little less money than what I've seen published for devces that use MoCA technology ... but still it's 100+ each, and you need at least two.
 

ronaldlees

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#16
Thanks for pointing them out - I didn't know such things existed, but they did not see as cheap as you suggested.

Is this what you mean?
It's been awhile since I looked for these, but this link may be what I've seen before. Again, I don't know if they work, but they're cheap:

https://www.amazon.com/NE-SE01-020Q-Seco-Larm-Passive-Ethernet-Extender/dp/B01718U2KQ

It's cheap dongle priced for a pair of them. I think I read in the reviews that they're not very good when there's a TV signal on the same coax.
 

PacketMan

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#17
One thing which puzzles me is that these devises are rated at, say 500Mpbs
Assuming the vendor is not too slimy that means (a) the ethernet port will run at 1Gbps, and (b) the bandwidth throughput will be up to 500mbps through the powerlines in your house. Mine are rated the same, and at best I get around 5 to 6 Mbps if I remember right.

It really depends on your requirements, as I've said before "what is the problem you are trying to fix". If its getting unsecure low bandwidth ethernet access in a room where there are no other options then powerline just might be the ticket. If you require more secure higher bandwidth access then Wifi, MoCA, or running your own CAT5/6 cable will be your options.
 

PacketMan

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#18
...and this thread should probably be moved to Off Topic since its not directly about networking with FreeBSD. :p
 

usdmatt

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#19
The passive adaptors seem to basically just be media converters. It doesn't look like you'd be able to use the cable for Ethernet, but still pass the TV signal over it as well? The other ones have cable in/out which suggest it can be put "inline"; I know nothing about this stuff though and can't seem to find anything that blatantly says "This device lets you send Ethernet and TV/Cable Internet signal over the same coax".
 

ronaldlees

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#20
The passive adaptors seem to basically just be media converters. It doesn't look like you'd be able to use the cable for Ethernet, but still pass the TV signal over it as well? The other ones have cable in/out which suggest it can be put "inline"; I know nothing about this stuff though and can't seem to find anything that blatantly says "This device lets you send Ethernet and TV/Cable Internet signal over the same coax".
I really don't know anything about them either. But, sometimes the simple/cheap stuff works "well enough." This is definitely not my endorsement :) - because "too good to be true" has been a discovery made often. But hey - maybe they'd work OK. I don't want to lend any weight either way ...

But, one of the reviews states:

"I purchased these to extend my internet data line to a room where I had a coax cable but no Cat5/6 ..."

The reviewer indicated that he was successful, FWIW.
 

usdmatt

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#21
"I purchased these to extend my internet data line to a room where I had a coax cable but no Cat5/6 ..."
Yeah I can find a lot of examples of using existing coax cable in a house to create an ethernet network using this stuff. This should work great and is an obvious solution if you have existing unused coax cabling but no cat5/6. I'm happy to be corrected here by someone that actually has cable experience, but I just can't find anything that clearly states you can use them on coax that is also handling tv or cable Internet service. (assuming OP is actually using TV service coming in over the coax).
 

ronaldlees

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#22
Yeah I can find a lot of examples of using existing coax cable in a house to create an ethernet network using this stuff. This should work great and is an obvious solution if you have existing unused coax cabling but no cat5/6. I'm happy to be corrected here by someone that actually has cable experience, but I just can't find anything that clearly states you can use them on coax that is also handling tv or cable Internet service. (assuming OP is actually using TV service coming in over the coax).
For my sources, I have only the reviews from the link ...

And one of them agrees with you: you can't use it simultaneously for ethernet and TV.

So, like you said, it's just a media converter, and has no protocol knowledge. Being passive, that's reasonable. Of course the OP could unplug the TV source, or switch it with a little coax switch to do internet, but that would be a hassle. Sometimes cheap is a hassle :) - and sometimes it doesn't work at all. Sorry if you thought you were being corrected. I don't know any more than you about these things.
 

aragats

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#23
If I installed my own cable modem would that connect to the ISP and auto configure itself?
Most ISPs register the modem's MAC address, and without that it will not be autoconfigured or allowed to get outside of the ISP's network. Most likely they will refuse to register another one for the same customer.
 

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#24
Yeah I can find a lot of examples of using existing coax cable in a house to create an ethernet network using this stuff.
Before UTP there was coax (10BASE2 and 10BASE5). In theory you could use it but it's only 10Mbit. And there's an impedance issue with the cable too, TV coax cable is 75 ohm, network coax cable is 50 ohm. You're going to have a hard time finding a network card that supports 10BASE2 though, they've become quite rare. I think I may have an old ISA 3COM card stashed in a drawer somewhere that has MAU, BNC and RJ-45 connectors.

But perhaps someone created a specific network adapter to piggy-back on the TV cable but I've never seen one.
 

usdmatt

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#25
Yeah I remember the old coax networking and daisy chained connectors. I'm not talking about actually using that stuff directly, but using these MoCA devices to send Ethernet over coax, breaking it out to standard cat[56]/rj45 for the actual devices to connect to. I expect these things can easily pass more than 10Mbps (in fact they specify 1Gbps for MoCA 2 although I expect that's total capacity if you have multiple of these on the same coax run).

My question is whether it's possible to plug a coax carrying TV signal, and Ethernet into one of these devices, pass both signals over a single coax, then break out into Ethernet and TV at the other end. I suspect not which means in OP's case he could use the existing coax to get a decent network connection between the rooms, but not have the cable TV service in there as well.
 
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