I dont think Cogent, or anyone for that matter, needs Level 3 any more. Peering is a very fluid thing and they have more than enough connectivity these days.
Level 3 is the one to blame. You can't just go from being a free-free peer to charging. Once a free peer, always a free peer ... or nothing at all, as is what happened.
Level3 by far the biggest of the tier1s now, almost 1/2 of the internet is a downstream customer, they seem to be able to do pretty much whatever they want.
