A submarine cable snaps in every three days while a terrestrial cable gets severed in every 30 minutes somewhere in the world. The global economy counts annual loss of US$26.5 billion due to such disruptions, estimates Ciena. Therefore, route-diversity is the fundamental prerequisite of uninterrupted Internet.
Early last year we reported the activation of cross-border terrestrial links between Bangladesh and India. The six Bangladeshi terrestrial link operators have been saving the country from getting disconnected. Late last year SEA-ME-WE4, the only submarine cable of Bangladesh, was down for nearly two weeks due to routine maintenance. It immediately hit latency, as shown in the graph above (click to enlarge). Thanks to Douglas Madory of Renesys for tweeting this image.