A BREAK IN A SUBMARINE CABLE CAN CAUSE SEVERE PROBLEMS

Christmas Day has always been the busiest day of the year for international telephone calls. People based overseas always want to call their relatives and friends in their home country on that day.
This Christmas, December 25, 2008, became a problem for such callers. Calls proved either impossible to make or were terminated in mid call. The voice quality was also bad.
Even voice over internet calls on Skype, for example, had problems.
In addition internet connection to overseas websites were very slow and the waiting time often unacceptable. This, in January, 2009 is still the case
So what caused these problems?
On December 19th, 2008, three high capacity submarine fibre optic cables were either cut or severely damaged, probably by a large ship’s dragging anchors. The cables involved in this accident were SEA-ME-WE 3(South East Asia-Middle East-Western Europe) and SEA-ME-WE 4. In addition FLAG FE (Fibre Link Around the Globe. Far East) was involved. The incident took place in the Mediterranean, off Sicily.
A heavy ship like a supertanker sails on for many miles even when the engines are running astern, and they need big, weighty anchors.
A cable ship, Raymond Croze, owned by France Telecom, one of the owners of the cables, is on the scene to effect the necessary repairs.
First however the ship had to find the cables. A dragging anchor can pull a cable a long way from its original as laid position. For this purpose a remotely operated vehicle (ROV) is used, connected to the ship by and umbilical cable for navigation and transmitting video of the sea bottom.
Once the cables were found the damaged sections are hauled out of the water aboard the cable ship where the repairs take place. This takes time. In the latest very high capacity submarine there are many fibres in the core. SEA-ME-WE 4 has 192 fibres which enable the cable to have a transmission speed of more than 1 Terabit per second Each fibre has to be repaired individually with a strong, clean joint that does not impair its optical transmission capability.
When cables like these are out of service massive disruption and damage can be done to business world wide. Many companies worldwide, especially the multi national corporations, have set up high capacity private networks to carry data and voice traffic between their many offices. Banks, stock exchanges, currency and commodity markets depend on them every second. For example a fall in the Dow Jones Index, instantly seen on the monitors in the trading rooms of other countries can trigger a similar fall, in the FTSE 100 for example. Then there is the vast amount of e-mail sent around the globe every day.
Data has overtaken voice as the main medium of communication for at least 10 years now.
Can these problems be avoided?
The answer is yes, most of the time, but breaks in three submarine cables in the same place is virtually unknown. Navigation charts show the marine crew the whereabouts of submarine cable zones and anchoring or deep sea trawling is usually prohibited in these areas. The trawler skippers often ignore the warnings, driven by the desire to get a large catch to port to sell it at the best prices. Large ships however, usually only drop their anchors in an emergency.
Fibre optic cable planners rely on achieving redundancy which means the ability to restore traffic over one or more other cables. Telecommunication companies sign reciprocal agreements with other cable system owners to achieve this. Redundancy was forcibly abandoned in this case by the fact that three cables were put out of service at the same time.
Let us hope that those anchors were dropped in a real emergency.