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I own a two-unit house, main and a basement apartment that are completely separated. However, should I decide to share the cable service between the two units, it would be very easy to run rg6 as I haven't hung drywall yet downstairs and I will probably do it for backup reasons.

Right now, there are two service cables running from the alley pole to the house, one for each cable service account. My question is: is each account allocated a fixed amount of bandwidth or is bandwidth determined on some group level, like my city block, or everyone who goes off of a certain service hub (alley pole) etc.? Because, in the former case, it would make sense that each unit in the house has its own service account for bandwidth reasons but in the latter scenario, it wouldn't make any difference as we would be sharing off of a larger network node anyway.

My service provider is Comcast and I am located somewhere in the Mid Atlantic region.

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Seems like a question Comcast should easily be able to answer. – Kyle Jones Dec 6 '12 at 19:00
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Both of those things are done. Bandwidth is divided among service endpoints, but available bandwidth per group is also limited. – David Schwartz Dec 6 '12 at 19:04
@KyleJones, i think Comcast will give me the answer that is conducive to their business advancement -- they are biased to be asked this – amphibient Dec 6 '12 at 19:12
It's shared with the whole node, you don't have a dedicated line so you are sharing with everyone else. How it's divided I don't know, but you are certainly sharing. – BroScience Dec 6 '12 at 19:28
Bandwidth is divided up at several points and you are sharing at each point. Each regional office has a pipe to it, this pipe is divided up to smaller areas and then to individual buildings (circuits). The total allotted to each the individual circuits is programmed in at the far end (CMTS) which is what the modem syncs to. The total of all these individual lines often adds up to more than the pipe to all the lines can handle (not everyone uses all of their bandwidth at all times). Whether you share a line or have individual lines from the same pole, you essentially have the same limitations. – MaQleod Dec 7 '12 at 1:22

1 Answer

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Cable bandwidth is a weird thing, at least the way its done in the states. DOCSIS multiplexing allows all the channels to be carried on the wire at all times. your box just focuses on a portion of the band to "tune in" to a channel.

this is much of the reason for the Digital switch over a few years ago. a analog channel takes about 4Mhz to carry (IIRC) but a digital channel takes only 2MHZ, and HD channels take between 6 and 8. in order to open up bandwidth for HD, they had to get rid of the wide analog channels.

this shared media leads to some bizarre oddities like this: http://www.slate.com/articles/technology/technology/2007/06/other_peoples_porn.html

On-demand content is demanded by the local cable hub, and is sent directly to the hub from the headend. at that point, every cable coming out of that hub is now carrying the ondemanded content, but usually no one except the person who requested it is tuning in. with a special cable tuner though, you can watch other people watching ondemand,, and even see where they fast forward, pause and rewind.

this all of course wastes bandwidth horribly, so eventually they will switch to 'Switched digital video'.

back to your question, bandwidth isn't your hurdle here, but instead tuning. just a couple weeks ago, the FCC started allowing cable providers to start encrypting their carrier for local OTA channels, so that a tuner box is required to access them. This means that you would need multiple cable boxes to watch even local channels.

Keep in mind though, with Internet service over cable, the cap you get is based on your service plan, and enforced by upstream hardware, so if you subscribe for 17Mbps service, thats all you can use, even if the carrier has plenty of bandwidth available.

hope that helps, and mabey brings a chuckle. good luck

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