Sunday, February 04, 2007

Bandwidth: why the net is slow and getting slower

We don't have anywhere near the bandwidth we need to support video-on-demand (which is why Netflix and the post office still have years to go). Cringely has been delving into various solutions (Googleplex, P2P), but here he delivers a short tutorial on how ISP's work ...
I, Cringely . The Pulpit . WYSIWYB | PBS

... At the heart of this video distribution problem is the lie that ISPs tell about how much bandwidth we are really buying. While you may think your 1.5-megabit-per-second DSL service or your 3-megabit-per-second cable modem service is actually backed by 1.5 megabits or 3 megabits of Internet bandwidth, they really aren't. ISPs provision backbone access based on the expectation that people usually aren't on the Internet, and even when they are on the Internet most of their time is spent reading the screen, not actively sending or receiving packets. As such, ISPs have been able to get away with buying 20-30 KILOBITS per second of Internet backbone capacity for every MEGABIT per second of Internet service they are selling at retail. This 20-to-1 provisioning ratio of what's sold to what is promised (and believe me, 20-to-1 is me being generous to the ISPs since it is probably much higher than that) is what creates the burgeoning Internet video problem.

So if ISPs would simply provision the amount of bandwidth they are selling us there wouldn't be a problem, right?

Alas, that's not the complete story.

What would appear to be an obvious solution to this impending problem is increasing effective backbone bandwidth for every broadband user. There is no LOCAL bandwidth crisis, just an INTERNET bandwidth crisis. As I've explained over the last two weeks, Google is going to solve this for us in exchange for taking the majority of global advertising revenue. Maybe that's the answer, in which case we don't have to do anything. But if Google doesn't step in appropriately or you'd rather not rely on Google for some reason, there is the alternative of going with a different ISP.

If you want a beautiful Internet video experience, one answer might be to buy service from a broadband ISP that will allocate more backbone bandwidth per account. If you are a DSL user, you have a choice of ISPs in most markets. They all go through the local phone company, of course, but that phone company has no problem allocating the rated value of the DSL line because to the telco that last mile bandwidth is free. My DSL ISP is MegaPath and they buy a 1.5-megabit-per-second circuit from BellSouth (now AT&T I guess, but the trucks don't say that yet) and it can really carry 1.5 megabits per second 24/7, no problem. The problem is that MegaPath then makes me share a DS3 (45-megabit-per-second) connection to the Internet with every other customer of theirs in my LATA or service area, so in practice I get a LOT less than my 1.5 megabits.

One would think a national DSL ISP would have a huge business advantage if they could sell me a 1.5 megabit service and actually PROVISION a 1.5 megabit service. The wholesale cost of Internet bandwidth is right now around $15 per megabit per month. So delivering a REAL 1.5 megabits vs. the 30 kilobits I am probably getting right now will cost my ISP 75 times as much, but that's still only $22.50 vs. $0.45. So the question is whether I would pay $22.05 more than I am paying right now to be able to effortlessly watch video over the net?...

Along the way Cringely admits that ISP's do have a legitimate grievance with "net neutrality". Their business model depends on that 20:1 provisioning ratio, but some kinds of net use are truly incompatible with that sparse provisioning. For things like video they have to buy much more backbone capacity -- so they bear a lot of extra cost. Of course they ought to be able to pass that on to customers, but imagine the screams from customers who aren't getting value from the streaming video ...

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