Trick or Treat: A Halloween Peering Surprise

By: Craig Labovitz -

Yesterday, tens of thousands of Sprint and Cogent customers got an early Halloween surprise. At 4pm EDT, Sprint and Cogent terminated their direct peering relationship.

The below graph shows traffic from the perspective of 25 tier2 ISPs around the world. All of these ISPs are direct customers of either Sprint or Cogent. And all lost transit connectivity from Cogent to Sprint (or vice versa). The graph shows all ASPaths matching “174 1239″ and “174 1239″ across these 25 providers. One minute several Gbps of traffic and then, well, poof.

Sprint - Cogent Traffic

For all but a couple of these ISPs, traffic quickly moved to alternative paths. Other ISPs like Verizon, Qwest, BT, and Level3 (who had their own peering dispute with Cogent last year) provided transit paths between the now partitioned two ISPs. Though, at least one ISP anonymously participating in the Internet Observatory lost connectivity to Sprint customers (and continues to drop traffic as of this blog posting). It pays to be multi-homed.

Why did Cogent and Sprint pull the plug on their peering relationship? I have no direct information, but money, traffic ratios, and maybe even egos are always a good guess. Cogent sent out a press releasing blaming Sprint for the termination.

The Internet has always had holes and strange partitions (e.g. see Dark and Murky Internet Address Space). The Sprint – Cogent dispute is just one more in a decade long line of business and policy issues disrupting Internet connectivity.

In the unregulated ISP interconnect industry, peering is a lot like trick or treating. Sometimes the competitive industry drives down prices and gives customers a treat. But today some Sprint and Cogent customers definitely got tricked.

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