Internets are fighting

[screwballl]

Quite literally, 2 major companies are severing links to each other and blocking traffic destined for the other, even if it is attempted to be re-routed through other networks.

Cogent-Telia Peering Dispute Widely Felt - Data Center Knowledge

Renesys Blog: You can't get there from here

What is surprising is that networks in the US are actually cut off from each another, since a largely US provider is playing hardball with a largely Swedish one. ... the list of impacted networks is too long to be included here, but they include a wide range of commercial, educational and government clients.

At this point, Telia lost direct access to 4474 prefixes (networks) transited via Cogent, whereas, Cogent lost 1633 Telia networks. Now, you might be thinking, "So what? Won't the Internet just route around the problem, finding alternate paths?" Well, yes if there are alternate paths to be found and if the players actually allow traffic to flow via them. For around 12 hours, most Telia customers did access Cogent via Verizon (56% of the 4474 networks), Level 3 (16%), AT&T (6%) and others, but then that abruptly stopped. We're guessing it's because Cogent eventually slammed the door shut on these alternate paths to their network from Telia, since none of Cogent's customers accessed Telia via alternate routes during this time. Like divorce court, depeering is supposed to be painful, otherwise you might not get what you want.

So if you are having problems emailing someone or trouble getting to certain sites, this is likely the cause. I know with my work at an ISP, people are complaining to us about things out of our control and using comments like "well we may have to look for another email provider" type of thing. I usually explain when this happens, it doesn't matter if you use the other provider (which we may have contracts through), they will have the same problem we will. Some people don't listen... oh well. Just remember, if your email is not getting through, don't blame your ISP or the other ISP quite yet, see which network the other is based on to see if that is the problem.

edit: and another mention from another site:

Cogent customers currently have a problem with people playing (or trying to play) World of Warcraft. This is (according to Blizzard Entertainment) due to a decision by Cogent not to connect to TeliaSonera's AS 1299. At this time, Cogent has not released any comment as to what they will do about this, but Blizzard and TeliaSonera have no control over the situation whatsoever.