The ongoing peering dispute between Cogent and Telia has left many networks in the U.S. and Europe unable to connect with one another. Renesys, which tracks Internet routing, has some additional details on the impact of the dispute, which it describes as an "Internet partition." Renesys says many networks are unable to simply route around the impasse, perhaps because one party (probably Cogent) is taking steps to block alternate traffic paths. Their analysis finds that 2,383 Telia network prefixes can't reach Cogent at all, while 1,573 Cogent prefixes are completely cut off from Telia. The impact is most widely felt in Europe, but more than 1,900 U.S. network segments are affected as well. Some additional detail:
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. On the Telia side, the victims include the Swedish Defense Data Agency, the Finnish State Computer Center, and broadband customers in St. Petersburg. With regard to Cogent, Blue Cross and Blue Shield of Delaware, Kansas State University and Reuters America were all collateral damage.
Renesys notes that Flag and SingTel recently discontinued peering, but are allowing customers to find one another via alternate routes. "For the Internet to be whole again, Cogent and Telia need to kiss and make up," Earl Zmijewski writes. "No one can force either one to carry traffic destined for the other. But my guess is that Telia is hearing more grief from Scandinavian customers not being able to reach US content than Cogent is hearing from US customers cut off from Northern Europe." Check out the Renesys blog for a table detailing the country-by-country impact.