Fiber-Optic Link Around the Globe

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Fiber-Optic Link Around the Globe (FLAG) is a 28,000-kilometer-long submarine communications cable containing optical fiber that connects the United Kingdom, Japan, and many places in between. The cable is operated by India's Flag Telecom, a fully owned subsidiary of Reliance Communications. The system runs from the eastern coast of North America to Japan.[1] Its Europe-Asia segment is the fourth longest[2] cable in the world.

The Europe-Asia segment was laid in the mid-1990s and was the subject of an extensive article in Wired magazine in December 1996 by Neal Stephenson. The cable was laid by NYNEX.[1]

Contents

Description of FLAG [edit]

The FLAG Cable System was launched in September 1997. FLAG offers a speed of 10 Gbit/s and uses synchronous digital hierarchy technology. It carries over 120,000 voice channels via 27,000 km of mostly undersea cable. FLAG uses erbium-doped fiber amplifiers and was jointly supplied by AT&T Submarine Systems and KDD-Submarine Cable Systems. With respect to design, development, installation and service FLAG conforms to all ISO 9000 quality standards. FLAG provides a link between the European end of high-density transatlantic crossings and the Asian end of the transpacific crossings.[3]

FLAG consists of several undersea cable segments and two terrestrial crossings. The segments can be either direct point-to-point links or multipoint links which are attained through branching units. At each landing point a FLAG cable station is located. The total route length exceeds 27,000 km and comprises 1020 km of terrestrial crossings. Approximately 6600 km of the submerged cable is buried 1 m below the sea bed. Cable burial was performed by either utilizing a submersible plough as the cable was laid or jetting the laid cable into the sea bed via remotely operated vehicles (ROVs).[3]

Over several years the route has evolved as new branches and feeder systems were considered and realized. FLAG includes two terrestrial crossings, one in Egypt and the other in Thailand. Each of these land crossings is totally duplicated on fully different routes. As a result, any fault within one route will cause automatic protection switching to the other route within a time period of less than 50 ms.[3]

Like other global undersea networks, FLAG uses erbium-doped fibre amplifiers. EDFAs boost the optical signals instead of the optical/electrical conversion which is generally used in regenerative technology. These amplifiers use short, gain-specific lengths of fibre which are doped with erbium ions and spliced in-line with the transmission fibre. The signal power is amplified by pumping the erbium-doped fibre (EDF) with 1480 nm laser light which is attached through an optical coupler. The majority of the repeater components are passive. These include EDF, fused-fibre optical couplers and optical isolators. Active components include laser pump assemblies and associated controls. The total number of components within the repeater is lesser than that of regenerative systems.[3]

The FLAG terrestrial crossings do not contain repeaters for reliability reasons. The terminal stations in land crossings use optical amplifiers, high performance transmitter/receivers and forward error correction to cross the large distances without repeaters. Amplification at the terminal output provides output signal power as high as 17 dBm, and optical amplification at the receiver improves the receiver sensitivity as high as 8 dBm.[3]

The route between Alexandria and Cairo is 223 km long and hence requires remote pumping in order to meet FLAG performance requirements. Remotely pumped amplifiers can be regarded as repeaters without active modules. This technology comprises short lengths of EDF spliced into the land cable. The erbium-doped sections are situated within the cable span and are pumped by 1480 nm pump lasers which are based at the station.[3]

Segments and landing points [edit]

Question book-new.svg
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Landing points are:

Segment FLAG Atlantic 1 (FA-1) [edit]

Segment FLAG Alcatel-Lucent Optical Network (FALCON) [edit]

Main article: FALCON (cable system)

Segment FLAG Europe Asia (FEA) [edit]

Segment FLAG North Asia Loop (FNAL)/Tiger [edit]

West of Mumbai, FLAG has a capacity of 80 Gbit/s.

The segment between Hong Kong and Busan was broken by the 2006 Hengchun earthquake.

Service Disruptions [edit]

December 2006 and January 2007 [edit]

The 2006 Hengchun earthquake occurred on December 26, 2006, off the southwest coast of Taiwan, disrupted Internet services in Asia, affecting many Asian countries. Financial transactions, particularly in the foreign exchange market were seriously affected as well.[4][5] The aforementioned disruption was caused by damage to several submarine communications cables.[6]

January and February 2008 [edit]

See also: 2008 submarine cable disruption

On January 30, 2008, internet services were widely disrupted in the Middle East and in the Indian subcontinent following damage to the SEA-ME-WE 4 and FLAG cables in the Mediterranean Sea.[7] BBC News Online reported 70% disruption in Egypt and 60% disruption in India[8] Problems were reported in Bahrain, Bangladesh, Kuwait, Pakistan, Qatar, Saudi Arabia and United Arab Emirates.[9] The respective contributions of the two cable systems to this blackout is unclear. Network outage graphs suggest that the two breaks occurred at 0430 and 0800 UTC.[10]

The cause of the damage has not been declared by either cable operator, but a number of news sources speculate that the damage was caused by a ship's anchor near Alexandria.[8][11] According to the AFP, the Kuwaiti government attributes the breaks to "weather conditions and maritime traffic."[12] The New York Times reported that the damage occurred to the two systems separately near Alexandria and near Marseilles.[13] Egypt knew of "no passing ships" near Alexandria which has restricted waters.[14]

One day later, on February 1, 2008, the FALCON cable was also reported cut 56 km off Dubai.[15][16]

December 2008 [edit]

On December 19, 2008 internet services were widely disrupted in the Middle East and in the Indian subcontinent following damage to the SEA-ME-WE 4, SEA-ME-WE 3 and FLAG FEA cables in the Mediterranean Sea.[17]

It is not known what has caused these multiple breaks, however there was seismic activity in the Malta area shortly before the breaks were identified,[17] although it is thought that the damage may be due to a ship's anchor or trawler net.[18]

According to FEA Cable System of Reliance Globalcom, the failure lay between Alexandria and Palermo. Reliance Globalcom completed the repair on the FLAG EUROPE ASIA (FEA) cable on December 29, 2008, at 14:15 GMT. Customer services that were affected due to the cable cut have been restored back normal with the completion of repairs.[19]

August 2009 [edit]

Damage to FNAL caused by Typhoon Morakot was reported as affecting internet traffic to China on 18 August 2009.[20]

See also [edit]

Other cable systems following a substantially similar route to FLAG Europe-Asia (FEA) are:

References [edit]

  1. ^ a b Wired 4.12: Mother Earth Mother Board Wired
  2. ^ Global map of undersea cables Guardian
  3. ^ a b c d e f Welsh, Thomas; Smith, Roger; Azami, Haruo; Chrisner, Raymond (February 1996), "The FLAG Cable System", IEEE Communications Magazine 34 (2): 30–35 
  4. ^ 網上銀行服務仍「斷纜」, Sing Tao Daily, 2006-12-30 (Chinese)
  5. ^ 韓股匯市受挫港交易無礙 星洲期貨受影響 「彭博」電訊一度中斷, Ming Pao, 2006-12-28 (Chinese)
  6. ^ Quakes disrupt Asia communications, CNN, 2006-12-27
  7. ^ "Internet failure hits two continents". CNN. Archived from the original on 2008-02-03. 
  8. ^ a b "Severed cables disrupt Internet". BBC News Online (BBC). 2008-01-31. Retrieved 2008-01-31. 
  9. ^ The Associated Press via nytimes.com (February 1, 2008). "Cable Break Causes Wide Internet Outage". The New York Times. Retrieved 2008-02-01. 
  10. ^ Zmijewski, Earl (2008-01-30). "Mediterranean Cable Break". Renesys Blog. Renesys. Archived from the original on February 3, 2008. Retrieved 2008-01-31. 
  11. ^ "Cable damage hits Internet connectivity". The Times of India. 2008-01-31. Retrieved 2008-01-31. 
  12. ^ "Indian outsourcing sector hit by Internet disruption". AFP. 2008-01-31. Retrieved 2008-01-31. 
  13. ^ Timmons, Heather (2008-01-31). "2 Communication Cables in the Mediterranean Are Cut". The New York Times. ISSN 0362-4331. Retrieved 2008-01-31. 
  14. ^ Brauer, David (February 4, 2008). "High-tech mystery: Are terrorists behind recent Internet disruptions?". MinnPost.com (MinnPost). Retrieved 2008-02-04. 
  15. ^ Flag Telecom
  16. ^ "Third undersea Internet cable cut in Mideast - CNN.com". CNN. 2008-02-01. Retrieved 2010-05-02. 
  17. ^ a b "Severed cable disrupts net access". BBC News Online (BBC). 2008-12-19. Retrieved 2008-12-21. 
  18. ^ "Third subsea cable repairs begin". BBC News Online (BBC). 2008-12-23. Retrieved 2008-12-27. 
  19. ^ Reliance Globalcom Cable Update Page
  20. ^ "Damage to undersea cables disrupts int'l telecom services". Xinhua. 2009-08-18. Retrieved 2009-08-18. 

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