In recent days Internet backbone operator Cogent Communications (CCOI) has reportedly discontinued traffic-swapping agreements with several providers, most notably content delivery network Limelight Networks (LLNW). These arrangements, known as "peering" in the network community, allow providers to exchange traffic with one another at no cost (or low cost) by establishing direct connections between their networks, instead of routing traffic across the public Internet. Reports this weekend on the mailing list for the North American Network Operators Group (NANOG) indicated that Cogent "de-peered" Limelight on Friday and WV Fiber on Sept. 17.
As we noted last April, Cogent is best known for two things: cheap bandwidth and peering controversies. At the time, Todd Underwood from Renesys found it unusual that Cogent was making the decision to drop a peer (rather than the other way around) and suggested this might be a sign of a strategic shift at Cogent. That post may get more attention with the company's latest peering moves, especially since Limelight is better known than the other providers Cogent has de-peered.
There's been no indication why Cogent ended its peering with Limelight, which peers with many other networks. Peering connections usually take place in data centers operated by peering specialists including Equinix (EQIX), Switch & Data (SDXC) and Telehouse, among others. Limelight has equipment in data centers operated by all three providers, so has many options to work around any issues created by Cogent's decision.
As for any impact on data center operators, both Cogent and Limelight have locations in most of Switch & Data's facilities. Since SDXC/PAIX has data centers in many secondary markets where Equinix and Telehouse have no presence, much of the peering between the two was likely through Switch & Data.