Just granting users the possibility of setting traffic priorities themselves, Briscoe believes, is enough to assuage concerns about network neutrality. “I suspect that 95 percent of customers, if they were given the choice between doing that themselves or the ISP doing it for them, would just say, Oh, sod it, do it for me,” Briscoe says. “The important point is they were asked. And they could have done it themselves. And I think those 5 percent that are complaining are the ones that wish they were asked.”
In Briscoe’s scheme, users could pay more for larger quotas of high-priority packets, but this wouldn’t amount to the kind of usage cap or “punitive tariff” that Odlyzko says ISPs are wary of. Every Internet subscriber would still get unlimited downloads. Some would just get better service during periods of congestion.
In order to determine which packets counted against a user’s quota, of course, ISPs would need to know when the network is congested. And that turns out to be more complicated than it sounds. If a Comcast subscriber in New York and an EarthLink subscriber in California are exchanging data, their packets are traveling over several different networks: Comcast’s, EarthLink’s, and others in between. If there’s congestion on one of those networks, the sending and receiving computers can tell, because some of their packets are getting lost. But if the congestion is on Comcast’s network, EarthLink doesn’t know about it, and vice versa. That’s a problem if the ISPs are responsible for tracking their customers’ packet quotas.
Briscoe is proposing that when the sending and receiving computers recognize congestion on the link between them, they indicate it to their ISPs by flagging their packets–flipping a single bit from 0 to 1. Of course, hackers could try to game the system, reprogramming their computers so that they deny that they’ve encountered congestion when they really have. But a computer whose congestion claims are consistently at odds with everyone else’s will be easy to ferret out. Enforcing honesty is probably not the biggest problem for Briscoe’s scheme.
Getting everyone to agree on it is. An Internet packet consists of a payload–a chunk of the Web page, video, or telephone call that’s being transmitted–and a header. The header contains the Internet addresses of the sender and receiver, along with other information that tells routers and the receiving computer how to handle the packet. When the architects of the Internet designed the Internet protocol (IP), they gave the packet header a bunch of extra bits, for use by yet unimagined services. All those extra bits have been parceled out–except one. That’s the bit Briscoe wants to use.
Among network engineers, Briscoe’s ideas have attracted a lot of attention and a lot of support. But the last bit is a hard sell, and he knows it. “The difficult [part] in doing it is getting it agreed that it should be done,” he says. “Because when you want to change IP, because half of the world is now being built on top of IP, it’s like arguing to change–I don’t know, the rules of cricket or something.”
Someday, the Internet might use an approach much like Briscoe’s to manage congestion. But that day is probably years away. A bandwidth crunch may not be.