On Sat, Oct 26, 2002 at 09:20:20PM -0700, Doug wrote: > I'm not trying to be a wise guy, just wondering what the difference is.
The difference is that cable tv sends the same data to everyone, i.e., the backbones only need to carry one copy of the data which is virtually the same for all subscribers. With Internet, everyone is sending and receiving different data. If everyone wanted to watch a different movie simultaneously, there would not be enough bandwidth (a television program or movie takes about 6MHz of bandwidth). Most cable distribution systems have a total bandwidth of less than 1000MHz (some only have about 500MHz). This is primarily used up by 50 to 150 or so channels, depending on the system. There are only a few MHz left for cable modems, which typically share one 6MHz channel (which is good for 30 to 40Mb/s). You need to understand how the system works. The only efficient way to make a network requires sharing bandwidth at some level (theoretically, you could string cables between every single pair of computers that need to talk to each other, but this would be horribly wasteful and inefficient and EXPENSIVE). And bandwidth does, of course, cost money. It is expensive to lay cables (usually having to dig holes, obtain right of way, etc.), to maintain the cables, to install and maintain the various amplifiers, regenerators, switches, and routers, and so forth. And you need to have an upstream connection to a major long-haul internet provider like Level 3 or UUNet or Cox or whatever, who has peering arrangements to connect your city to other cities. That is usually a T1 (1.544Mb/s) or a T3 (44.736Mb/s) or some combination if it is a large ISP. I remember only a few years ago a T1 cost more than $1500/month, now they can be had for $500/month. But that is still more than most people are willing to pay for broadband. So what you get is essentially a party-line-T1. It is hard to get information on how many subscribers the broadband suppliers put on each T1, but I guess it is around 15 to 50, depending on the provider. This allows them to charge $30 to $50 dollars for a connection that is "burstable" up to T1 speeds, but the system doesn't work if each customer saturates it 24/7. As long as people are only using their connection to surf the web and download the occasional file, it works out okay, since most people are using their connection on the order of 1% of the time (guesstimate), and somewhat randomly (but not totally random -- slowdowns are common at "peak" times) so there isn't a lot of overlap. However, if someone starts running a server (eg., porn web site or peer-to-peer MP3 or DVD file sharing) that OTHER people throughout the Internet access 24/7, then that can easily saturate the entire T1 and ruin the bandwidth for 15 to 50 other people. The best solution to the problem is to meter bandwidth usage and charge accordingly. That way, those who use the most bandwidth have to pay the most, and therefore will be encouraged to "conserve" bandwidth, or if they must use it, then their payment will encourage bandwidth providers to install more capacity and build on the network. However, the technology to monitor and account for bandwidth usage, while straightforward, isn't easy or cheap. In addition, some people seem to believe it is their god-given right to use tons of bandwidth and only pay $30/month. So the bandwidth accounting system hasn't been installed yet, and the ISP's use artificial means to keep things going, such as prohibiting servers and peer-to-peer file sharing. Hopefully, they will install the bandwidth accounting systems soon so that we can use as much bandwidth as we are willing to pay for in whatever way we want, rather than having these artificial restrictions on what we can do with the bandwidth that we have. Some people argue that it is the fault of the broadband ISPs for making false promises of super-high bandwidth connections for $40 per month. While it is certainly true that the ISPs haven't been pointing out what I described above, I can't really blame them too much. How many people do you know who would bother to read through what I wrote and understand it? Besides, the people making these claims are only hurting themselves in the long run, since if they want the bandwidth resource to increase, they should support a free market and paying fair prices for each bandwidth consumer, thus attracting more bandwidth suppliers in a classical, efficient free-market system. I forgot to mention @Home in one of my previous messages as another backbone provider who went out of business (they were the biggest cable modem bandwidth provider at one time). Building broadband networks to the home is expensive; most of these companies went into debt to do it, and they could not recoup their investment. The only survivors are the companies that have other revenue sources such as cable tv, so that they can take a loss on the data service for a few years and still keep in business. But sooner or later they will have to start charging fair market value for the bandwidth. Here's a good IEEE Spectrum article about cable modems: http://www.spectrum.ieee.org/WEBONLY/publicfeature/jun01/cmode.html -- "Erik Reuter" <[EMAIL PROTECTED]> http://www.erikreuter.net/ _______________________________________________ http://www.mccmedia.com/mailman/listinfo/brin-l
