Millions of people already use the Internet and Internet service providers (ISPs), so any shift to SLAs and some form of pricing for the Internet-either on a per-byte or subscription basis-would be a radical shift and probably an unpopular one.

Even though Southworth is from the United States, he, along with several other founders, formed AdEvia (www.adevia.com) to address the global Internet market from a European base with U.S. deregulatory zeal. Southworth was previously with Concentric Network Corp., where he was senior director of advanced network services and technologies. But he is perhaps best known as technical director of the DSL Forum industry body. And, with more than 10 years of Internet experience spanning numerous technologies, including applications and Internet service provision, Southworth is an authority on most things Internet and access technologies such as DSL, fixed wireless and two-way satellites.

"I think the traditional Internet is starting to go away," Southworth said. "In the early days the Internet was a U.S.-government-sponsored entity. Since then there has been a commercial free-for-all, with tens of thousands of service providers all joining in at random making their own peering and transit arrangements."

Southworth explained that each of these entities "agrees" to carry the traffic of the other ISPs on the premise of symmetry-they give out what they take back. Well, according to Southworth, the premise is invalid, and some host centers are violating their peering agreements.

Other models, for instance the international voice telephony carrier model, do not assume symmetry and contain a mechanism for measuring calls and to allow different carriers to buy and sell bandwidth and pay each other for carrying calls.

So does that mean that the Internet, which so far has existed as a free Internet Protocol packet network piggybacking on the traditional telephone network, will become a pay-per-byte medium?

Southworth said such a development is almost a requirement now, due to the need to recognize the value of the data being transferred and to ensure that demanding applications are able to operate.

"We are already seeing premium subscription services being offered by some ISPs, which might be on the basis of some parameter or other-the nature of the data, uptime, bandwidth and the like.

"Uunet, Connection Networks, Sprint and MCI offer premium services while you are inside their individual domains," Southworth continued. "The next level would be an agreement with an ISP that covered the traffic handled by ALL of these."

It's possible that the lowest level of Internet service, the level we are used to today, will remain nominally free. But Southworth said that for higher levels of service, change is inevitable. And that's all because of a problem called jitter.

In the United States, where Internet traffic passes through a minimal number of hops, it's possible to push the travel time for a coast-to-coast signal down to around 80-ms. But without minimal hops, signal times can quickly escalate above the 300-ms mark, considered to be the maximum for interactivity, Southworth explained.

In the networking context, jitter is the variable arrival of packets before and after they are expected. While it is simple to assemble the packets into the correct order, so as to reconstruct a picture or an audio stream, this can only be done after the latest packets have arrived. One way networks cope with this is to build jitter buffers to corral data that is being assembled.

"Jitter obliterates voice and video codecs. Jitter buffering is necessary and introduces a fixed latency," Southworth said. "You add a few of those together and you quickly get above 300 ms." For a one-way feed, a delay of several seconds may be acceptable. But for interactive sessions such as voice-over-IP telephony or teleconferencing, there is a threshold at about 300 ms beyond which the application does not work.

Southworth suggested that customers, particularly commercial customers, might be prepared to pay a premium to provide, say, less than 1 percent packet loss and less than 1 percent jitter and 100 percent uptime.

But at the moment, because of the ad hoc nature of the Internet, it is not possible for an ISP to provide a customer with this sort of guarantee. Therefore, some form of contractual system-level agreement between carriers is necessary for voice-over-IP video and multimedia services. And Southworth thinks superhubs are the way system-level agreements are likely to burrow into the market.

System-level agreements between ISPs and Internet traffic carriers are not just about latency and packet loss, Southworth said. "It will be about security, availability; any parameter that can be measured and can contribute to higher performance."