lies, damn lies, and network traffic statistics

How do traffic engineering and core network design impact the cost and performance of an IP network? I have long seen ad hoc capacity augments as the most blunt and most expensive of tools to improve network performance. But I'm beginning to have doubts, or at least I'm doubting that I can prove my point.

In theory, a traffic-engineered network will be cheaper and perform better than a "native" network. In practice, it seems that demand path and demand volume uncertainty means any IP network backbone has to be significantly overbuilt to achieve the highest level of performance and reliability. If that's the case, then one of the arguments for traffic engineering-- lower network cost-- is invalid.

The problem is that in practice backup paths even in a traffic-engineered network have to be overbuilt. In some failure or surge scenarios, the backup paths are liable to take traffic greater than expected from measurements of normal operating conditions. The solution is the fine art of ad hoc overprovisioning of backbone capacity: something we say we don't do.

Before you think this post is confessional, let me state that I think a traffic-engineered network is less expensive than a "native" network. But I would like to know for sure, and be able to prove what I know. How big do you have to build a "native" network? How big do you have to build the same network using various traffic-engineering schemes? It isn't true in practice that we build it only as big as the traffic-engineering scheme and network statistics say we should. We overbuild it above and beyond what the simulations say we need. How much bigger would the same "native" network be, in practice?

I suspect the answer will show that the costs are similar for different traffic engineering schemes, and the choice of traffic engineering scheme depends mostly on operations, vendor selection, and product specifications. In other words, there is probably little reason to change traffic engineering schemes once one is in place, because the cost and performance of various schemes is almost equal. Presuming that any reasonable choice can be made to perform effectively, given enough bandwidth, consider that the IP backbone equipment in a network is only about 10% of the total network cost. The most expensive part of the network is at the edge, where the customer services are provisioned. Even doubling the cost of the IP core would only add about 10% to the total network cost. When you're trying to live within your budget, that's a big deal. But when you're talking about the competitive advantage of one scheme over another one that's peanuts, and the winning carrier will have better reach, customer service, and performance, not a better traffic engineering scheme.

But I can't prove it, and that's the point of this post.

good, bad and ugly

It looks like I'm on a one-post-per-month pace. Gonna have to pick it up a bit.

I've been going back and forth on net neutrality. As it stands right now, common carriage does not apply for Internet connectivity. Carriers are free to engage in price discrimination: they can charge customers different rates for the same service.

That's pretty jarring. It wouldn't be right for a shipping company to charge one rate to one customer and another rate to another customer to carry the same container. But that is less clear if one of the customers is offering a service that competes directly with the shipping company. If the shipping company offers to pack the goods at the point of origin, wouldn't it be reasonable to charge the customer that uses the packing service a lower rate for the long haul shipment? The second customer might be competing for that very business, packing the first customer's goods and delivering them to the dock.

In telecom, there are a lot of good reasons why I'd want common carriage to apply. For starters, cable and phone companies use rights of way for their fiber routes and spectrum for their wireless services that are regulated for the public good. It's reasonable to expect the carriers to submit to some regulation of their rates and services. Offering service to most of the population is part of the deal, to give one example. Common carriage is basically part of the deal, too, for "communications services" like old-fashioned telephone service. But the FCC has ruled that the Internet is an "information service" not subject to common carriage.

This galls when I think that my very low cost Skype and Yahoo! services could go away, or my free Blogger account. I've paid for my bandwidth, now give it to me! The public statements made by the big carriers appear to be off the mark at best, misleading and disingenuous at worst. Statements about future costs appear to be mere scare tactics, because carriers will always be free to charge more for more usage, just like they used to for telephone usage. If the cost of future services runs to hundreds of dollars a month, consumers will decide whether to pay for them or to stick with their "old-fashioned" HDTV cable service and telephone service.

Something else is galling, too: a limited rollout of very high speed services to homes and businesses. I want my future very high speed Internet. I want fiber to my home and office, I want ultra-fast broadband wireless, and I want my future news, entertainment, and communications to be high-def and on demand. If the way to get that is to deregulate carriers, then so be it.

Without net neutrality, carriers have more incentive to build out their networks. That is good. But the carriers will be in a position to play kingmaker between application providers. That is bad. We could wind up with a balkanized Internet, and the applications available to me over the carriers that serve my house could be different than the applications available to you at your house. That would be ugly.