Subsea Cables & Internet Infrastructure

Part 1 finished by noting that that the CLS in most cable systems has been downgraded to a building housing just the power feed equipment. This reflects the open cable model where each owner has fibre pairs or spectrum as opposed to a cut of the cable't lit capacity. A good example is 2Africa in Senegal. Most of the SLTEs (subsea line termination equipment) are collocated in the carrier neutral ONIX facility. But Facebook decided to put its SLTE in one of three N Plus data centers.  Another important element is the branching unit, which originally just took the main trunk's fibre pair and allocated them into two small trunks. TAT8, the first fibre optic cable, used a branching unit to land one fibre pair in the UK and the other in France. Branching units have evolved over time and most today have the ability to switch wavelengths and more recently fibre pairs. The advantages include being able to reroute traffic in case one branch fails. The branches are typically buried on the...

Benoit Kowalski gave the presentation at the event. The diagram below shows the standard subsea network architecture. The fibre optic cable and optical amplifiers are collectively called the wet segment. The rule of thumb is to bury the cable in waters a thousand meters or less deep. Approaching shore one has a choice. One can give bring the cable ashore using small boats. The cable initially lies exposed on the beach up to the beach manhole. Then the cable is buried from some point in the water up to the manhole where it is spliced into the front haul fibre that carries the signal to the cable landing station. From the CLS back haul fibre goes to a carrier neutral data center that serves as a point of presence (POP) or interconnection point. The other platinum-plated approach uses horizontal drilling to install a bore pipe from the manhole to a point on the sea floor offshore. This is much more expensive, but better protects the cable.  A couple of things to note. I...

Dr Kowalski is a Nokia employee who collaborates with ASN. His presentation on the first day of the conference is a good subsea cable primer.  The transmission equipment is known as the submarine line termination equipment or SLTE. It has three key components. Encoding involves taking the digital input and converting it into a series of laser commands according to the modulation scheme. FEC or forward error correction adds redundant bits called parity bits that help the far end FEC to detect and correct payload mistakes. It is a bit like a router creating the checksum field in the IP packet header. Once quality is control is completed, the laser sends the optical signal. Its ever weakening light travels the fibre until it is passively boosted by erbium doped fibre in the amplifier that has been raised to a high energy level by pump lasers. At the far end of the linear transmission the steps are reversed. The optical receiver takes the light signal and converts it into the appropria...

This project seeks to link Asia to Europe via the Saudi Arabian desert. Telecom Egypt is not a consortium member, which suggests it will bypass Egypt to avoid transit fees and provide new network routing diversity. Frankly, little known is about the project. Key consortium members including center3, a Saudi Telecom subsidiary, the Cyprus incumbent, a Greek power company, and a Greek satellite company. The consortium was formed on May 31, 2022. In May 2023, center3 signed a supply contract for the project with ASN. A supply contract in force suggests the consortium has raised the $850 million required to complete the project.  I believe the high price tag reflects either a new route across the Saudi Arabian desert or a high fibre pair count. The project is bound to be controversial in Saudi Arabia because the terrestrial route traverses Jordan's Aqaba data center and reaches the Mediterranean Sea via Israel. Note that the Jordan label is much larger than the Israel label. This proba...

There are a large number of desperately poor African states below Senegal and above Cote d'Ivoire on the West African Coast that have access to only one or no submarine cables. These nations include Liberia, Sierra Leone, Guinea, Guinea-Bissau, and the Gambia. Landlocked countries that would benefit from more subsea capacity adjacent to these coastal states include Mali and Burkino Faso.  Right now their main bandwidth supplier is ACE, which lands in all the listed coastal states. ACE is ASN's problem child. The kid that is always getting into trouble. It has a reputation for outages and network disruptions. The cable landing station operators in general hold the cable hostage. In Sénégal Orange manages the facility, charges high cross connects fees, and hence has a quasi-monopoly on its capacity. Similar problems bedevil ACE cable landing stations in general. In some countries an ISP consortium manages the cable landings, but abuse still occurs. In Sierra Leone, the government...

Americans like to focus on the first short lived Trans-Atlantic cable, a project completed in 1858. But the first commercial and successful subsea communication cable connected Paris and London. The honors go to the startup English Channel Submarine Cable Company, which two engineer brothers, Jacob and John Watkins Brett, founded. Its first attempt in 1850 failed. There are several differing accounts. What these accounts have in common is that the cable had no protection. One colorful story is that the cable lasted 24 hours before a French fisherman cut the cable thinking it was a new type of seaweed. According to this account, the cable sent a telegraph message to Prince Louis Napoleon Bonaparte before the cable died. Other more reliable accounts suggest the cable never worked at all. But the second attempt in 1851 using armored cable was successful. Commercial telegraph service between London and Paris began November13, 1851. Landing points were near Calais and Dover. It was viewed a...

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