Internet backbone firm Level 3 has fallen out with Cogent Communications, leaving some users in danger of being isolated in network cul de sacs.

Level 3 dropped its peering arrangement with tier 1 ISP Cogent Communications yesterday, because it felt it was carrying more traffic under the deal than Cogent, and wanted compensation. Level 3 has, apparently, been putting pressure on companies where it feels peering arrangements are too one-sided.

Cogent is standing its ground though. A statement on Cogent’s website today said “Level 3 has partitioned its part of the Internet from Cogent's part of the Internet by denying Level 3's customers access to Cogent's customers and denying Cogent's customers access to Level 3 customers.”

While multihomed Level 3 customers can get round the problem, according to Cogent, those that aren’t can’t exchange traffic with Cogent customers. Cogent said it was offering such customers a year of full Internet transit for free. Hopefully the spat will not take this long to settle.

A spokesperson for Level 3 in Europe could not comment on the debacle, while Cogent did not have anyone available to speak.®