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Cuban Fiber: Completo?



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Cuban Internet connectivity continues to evolve by the hour, with a new, faster mode of operation in evidence as of this morning. Our measurements from around the world suggest that Cuban technicians may have completed the work they began a week ago, creating the first bidirectional Internet paths that are free of satellite connectivity. viva-cuba-fiber.jpg

In our previous blog, we described how we first detected the signs of change in Cuba’s Internet connectivity on Monday, 14 January 2013. Before that date, everything sent to Cuba experienced a delay of at least half a second, because of the speed of light: every packet sent and received had to travel around 70,000 km (44,000 miles) through space, bouncing off of geostationary satellites and returning to Earth.

On January 14th, we began to see routed paths for data flowing inbound to Cuba through a new service provider, Telefonica. At the same time, we saw a second “mode” of latency for Internet traffic emerge, with reduced delays in the 400ms range. That’s fast enough that at least half the path must be terrestrial; we inferred that we were seeing signs of the activation of ALBA-1 from Venezuela.

For the next week, however, nothing changed. People on the ground in Havana reported no changes in Internet performance. When we wrote our blog on Sunday, it wasn’t clear whether this curious one-way connectivity was intentional, or the result of misconfiguration.


Today, that all changed. At exactly 14:01 UTC Tuesday (09:01 local time), we saw yet another mode emerge in the latency diagrams. In this plot, you can see the original pure-satellite mode (A), the new asymmetric satellite mode (B), and a third, lower mode (C) that excludes the possibility of geosynchronous satellite service altogether. At 180-220ms, these paths suggest a pure terrestrial solution, based on subsea and overland cables — the traditional Internet that nearly everyone else on earth enjoys. Almost immediately, we started getting reports from Havana that delays for Internet traffic were dropping perceptibly, as the new routing policy kicked in.

What happened here? We speculate that Cuban network operators changed their routing policy to make the ALBA-1 cable the default path for all outbound traffic from certain Cuban networks. That would align with what we see in the data: some satellite providers, like Intelsat, move from mode A to faster mode B (becoming asymmetric: cable outbound, satellite inbound), while some prefixes move from mode B to still faster mode C (becoming symmetric terrestrial: cable outbound, cable inbound).

We’d like to hear confirmation from the Cuban network operators themselves, and we hope they’ll comment below.

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Doug Madory
Whois: Doug Madory

Doug Madory is a Director of Internet Analysis at Oracle Dyn where he works on Internet infrastructure analysis projects. Doug has a special interest in mapping the logical Internet to the physical lines that connect it together, with a focus on submarine cables.