Two major Net companies stop exchanging traffic, cutting off access to each other's networks for some customers.
On Wednesday, network company Level 3 Communications cut off its direct "peering" connections to another big network company called Cogent Communications. That technical action means that some customers on each company's network now will find it impossible, or slower, to get to Web sites on the other company's network.
William Steele, a senior network engineer for Syncro Services, said his company noticed the problem Wednesday morning.
"There are some people I can't send an e-mail to," Steele said. "At home, I have Road Runner as an ISP, and wasn't even able to remotely connect in order to manage our servers."
"Peering" arrangements are maintained by network companies that agree to connect their networks directly together to exchange traffic more efficiently. When the companies are of roughly equal size, money rarely exchanges hands.
Level 3 contends that its arrangement with Cogent is no longer financially viable, since it is larger than the other company. It has asked Cogent to seek other arrangements, possibly including paying for the traffic exchange, a Level 3 representative said.
Cogent CEO Dave Schaeffer contested that claim, saying that its network is at least as big as Level 3's, and that it makes no sense to pay for the connection. Cogent is offering any Level 3 user who can't get to Cogent sites free Internet service for a year, in an attempt to attract its rival's customers.
"Our goal is to have this problem go away, whether through Level 3 reconsidering or their customers coming to us," Schaeffer said.
The Level 3 representative said the company was unlikely to reconsider its position, however.
The problem is likely to affect only a small number of each company's customers. Many network company customers have several connections to the Internet and can use an alternate connection to reach a site that might otherwise be blocked.
A similar Net blackout happened in 2001, when Cable & Wireless and PSINet were embroiled in a billing dispute.