Subsea Cables and Global Communication Infrastructure

Smiling Katie Taylor won an Olympic gold medal for Ireland on August 9th 2012; The Irish soccer team had European championship forays to Poland in 2012 and France in 2016 and the craic was 90; The O’Donovan brothers ‘pulled like a dog’ to bring back silver medals from the Rio Olympics in 2016 and Ireland finally beat the All Blacks on July 9th 2022 on their 29th attempt at soldier field in Chicago.


Like many Irish people, I love my sport and whenever any Irish person or team represents my country, I do my best to tune in and lend my support. But did you ever wonder how the broadcasts, the videos, the photos and the phone calls make it from Rio, Poznan or Chicago across those vast seas and oceans and into your living room quicker than you can blink an eye?


Most people assume that it is Satellite communications and while that is the case for around 1% of global communications, the remaining 99% of traffic is carried via fibre optic cables. These fibre optic cables span countries in duct enclosures along roadways, railways and bridges, but they also span continents. How do they do that?


They utilise sub sea cables. All of the digital data from our phones, TVs, laptops - those 1s and 0s that computers understand are converted into light by transceivers on optical nodes and are transported around the world inside fibre optic cables, amplified over 1000s of kilometres, with minimal delay. That’s the beauty of light you see, it’s speed.


Light, at a speed of 300,000 km per second and an earth circumference of 40,000km, can travel around the world 7 times inside a second – you see I wasn’t exaggerating about the blink of an eye! It's interesting to think that any data you consume on a daily basis from Netflix to TikTok was light for a while.


The map in the images below shows these cables and as you can see the majority of capacity spans the Atlantic between America and Europe and the Pacific between America and Asia. There are 485 of these sub sea or wet links as they’re also known distributed around the world and another 70 or so in planning.


These systems connect continents, countries and cultures and given that we are all about making connections that really matter here at Virgin Media Ireland, it’s fitting that our teams – The Optical Engineering team and Planning and Engineering teams are responsible for the Irish side of one of these systems, namely Sirius South.


Indeed, If you were a Virgin Media customer between 2012 and 2022 when the sporting events I mentioned above took place, then that data reached you through one of these sub sea systems linking the outside world to Ireland.


The second image below gives you an idea of what a sub sea cable looks like. The fibre strands in the centre are where the magic happens and a typical subsea system will have anywhere from 8 and 96 of these fibre strands.


Each fibre strand or core is around as thick as a human hair and they are wrapped in layer upon layer of protective materials to handle the pressures of residing on the bottom of ocean floors and sea beds around the world.


By utilising Dense Wave Division Multiplexing (DWDM), these systems can carry vast amounts of data (up to 400Tbps as demonstrated recently on the Amitié system linking Lynn, Massachusetts to Widemouth Bay, England and Le Porge, France – that’s a fair few streamed episodes of True Detective!).


Wondering what DWDM does? Well, in simple terms DWDM breaks the light wave on each fibre strand into 44 or 88 separate wavelengths much like the Prism on the front of Pink Floyd’s excellent Dark Side of the Moon album (which coincidently was released on this day 49 years ago!) Like the prism on the Pink Floyd album cover (see image below), DWDM systems also use prisms and mirrors, which are known as gratings to break the light out into individual wavelengths or colours. This increases the overall capacity by a factor or 44 or 88 and each wavelength can used to transport up to 800Gigs of data.


The Sirius South 48 Core fibre mentioned above landed in Ireland at Portmarnock beach in 1999 and the Optical DWDM equipment and Raman Amplifiers resided in the Beaumont Hubsite in Butterly Business Park for the past twenty-five years. Over time the Beaumont site grew to be Virgin Media Uk’s second biggest Irish hub site and Virgin Media Ireland engineers have dealt with all Operational activities on site for VMUK during that time. The site also houses another 30 racks of telecoms equipment for VMUK, VMIE, Eir, BT and other third parties, which Virgin Media Ireland engineers helped operate.


Many a long night has been spent in Beaumont by our dedicated engineers, when the dreaded news arrived from the NOC that there was a sub sea break on Sirius South. That’s the thing with sub sea fibres, they break too, and it’s a little bit trickier to fix something that is on the bottom of the Irish sea! From break to fix it can take anywhere from seven to fourteen days and it is all hands on deck!


It involves a very specialised boat, an on-board team of engineers, a ROV submersible robot, and an engineer at both ends in Dublin and Lytham armed with an Optical Time Domain Reflectometer (OTDR) and lots of patience! In a nutshell the OTDR allows the engineer at each end to send a pulse of light down the fibre core, and the equipment can calculate to within a few metres where the break is. This is made possible by knowing that the speed of light is a constant unchanging value and timing how long it takes the pulse of light to return after reaching the break and bouncing back to the OTDR. So, what’s the only thing worse than receiving a call about a sub sea fibre break on Sirius South in the middle of the night?


It is receiving a call from VM02 telling us that they need to vacate the Butterly business park site in Beaumont and is there anything we can do to assist them to decommission the site and all 30 racks of hardware? Remember we are talking about VMUK’s second busiest Irish site and landing station for Sirius South.


We quickly formed a project team and came up with a strategy with our VM02 colleagues and over many challenging months we came up with plans and designs, we carried out audits, we swapped out equipment, we installed equipment, we diverted fibres, we migrated services to Clonshaugh, we redirected Sirius South to Clonshaugh and we updated records and in the end we went from the before photos below to the after photos below.


This was a huge program of works with many late nights completing migrations and could never have happened without the professionalism, drive and commitment of a diverse mix of teams across the business, apologies if I left you or your team out.


A massive thanks goes to our Fibre Planning team, our construction team, our Optical engineering team, our Power and Cool team, our Wholesale team, our splicing partner and specifically to Sam Seymour, John Brocklebank, Andrew Phelan, John McKeown, Kevin Young, Roland Hughes, James Dunne, Noel O’Reilly and Stephen Jenkins who worked tirelessly on this project with me over the past eighteen months. Well done folks.


So, when you’re watching John O’Shea leading Ireland to inevitable world cup glory in 2026 in USA, remember that those broadcasts, videos, photos and phone calls are travelling across the Atlantic ocean at the speed of light on sub sea fibre and will land in Ireland to Virgin Media customers on connections via Sirius South and other sub sea connectivity that our engineering teams help make possible year in year out.



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