terabits (and risks) under the sea

Satellites get all the glamor with their showy rocket liftoffs and space shuttle missions, but in reality, over 99% of intercontinental data traffic travels via undersea cables which crisscross the planet’s briny depths.  These vital telephone and Internet links are exposed to a number of dangers ranging from seismic activity to misplaced ships’ anchors and fishing gear, to pirates and cable thieves, and when one of these links is broken, the effects can span countries or continents.  Upping the risk level is the fact than a large number of cables converge at a small number of geographic choke points such as the Suez Canal, and the Malacca and Luzon Straits.  When cables in these areas are damaged, there is a domino effect as traffic has to be rerouted to avoid the break.

In April of this year, the SeaMeWe-4 cable, which carries 89% of the traffic between the Middle East and Europe, was cut, severly impacting Internet and telephone communications between the two areas.  In 2008, a series of cable cuts in the Middle East disrupted network access and spawned a number of conspiracy theories due to the fact that neither Iraq or Israel were affected.  Back in 2006, a major earthquake cut the APCN2 cable connecting China, Hong Kong and other Asian countries bringing online commerce to a halt for days and resulting in network performance disruptions for months.

The good news is that notice is being taken – the IEEE held a “Global Summit on the Reliability of Global Underseas Communication Cable Infrstructure”  (ROGUCCI for those in the know) in Dubai in October 2009 where experts came from all over the world to discuss how to keep our undersea cables safe and secure.  I took a look at the report from this conference and learned some other interesting facts about undersea cables:

  • Undersea cables are one of the rare places here on Earth that we get to see the effects of the speed of light.  As data or voice traffic takes its journey through cables, there can be a delay of up to a tenth of a second, which can be heard by humans and interfere with time sensitive data communications.  Satellite latency is even larger – this is one reason why all that intercontinental traffic can’t be rerouted via the heavens.


  • Every second, the planet’s undersea cables carry 30 terabytes of information from continent to continent – and more data is added to this torrent every day.  (I think that 28T of that traffic is porn…)


  • When there is a cable failure, traffic must be rerouted by other cables, making the path taken by the data much longer, increasing latency and adding traffic to links which may already be congested.  There is no Plan B for the undersea cable network.


  • Cable ships and their crews are a shared resource – the number of simultaneous repairs that can be performed is limited.  Time to repair is also extended due to some countries’ bureaucratic permit processes which the repair ships must complete before entering their territorial waters to get to work.   Cable ships are also a potential target for pirates – cable operators worry that pirates could take over a cable ship and demand a hefty ransom for its release, delaying repairs further.  Pirates have already caused problems for cable laying off the coast of Africa.


Undersea cable security needs to be on all of our agendas… the Internet links that allow me to post this blog entry from my hotel room in London are also the ones which major financial institutions use for moving money around the world and which an increasing amount of commerce depends on.    Governernments need to safeguard cables and cable repair ships and most importantly, build the redundant links which will allow our planetary nervous system to recover from damage.

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