Have you ever thought about the infrastructure behind the everyday things we do online, like shopping, streaming a TV show or updating friends on Facebook? It’s something many people take for granted, but there is a complex, interconnected submarine network keeping everyone connected. Darrin Webb looks at what it takes to build a world class subsea cable network.

As more people around the world consume more and more data and digital products, the cable network under the sea becomes increasingly important.

Submarine cables carry more than 99 per cent of international data traffic (satellite accounts for less than one per cent). Telstra operates the largest submarine cable network in the Asia Pacific, accounting for up to 30 per cent of active intra-regional capacity. Our latest addition to our network is the Tasman Global Access (TGA) submarine cable system, which is designed to significantly improve connectivity between Australia and New Zealand and to strengthen New Zealand’s links with Asia. Once completed, the TGA cable will run 2,300km from Raglan in New Zealand to Narrabeen, just north of Sydney in Australia.

As one of three consortium partners building the cable, we are responsible for coordinating the multitude of tasks involved in adding a new part to the global subsea internet architecture and landing the cable in Australia. This week marked a significant milestone as the Ile de Re, a specialist cable, ship docked near Narrabeen to start laying the cable from the Australian side. On hand to meet the ship was a large crew, including a dive team to help connect the cable from the land out to sea.

So just what does it take to build a subsea cable network?

Building and maintaining a submarine network can be complex, involving multiple regulatory rules in different markets, and requiring specialist boats and skills. It’s a serious logistical exercise, but can broadly be broken down into three steps:

1. Planning. The longest part of the process. There are a number of factors that go into developing the plan – from gaining the necessary permits and licenses to mapping. Sonar technology is used to physically survey the underwater area so we can determine the best route. To do this we take into consideration things like the depth of the seafloor and whether there are any underwater obstructions in the area, like shipping containers, which often fall off container ships. In simple terms, the deeper the water the safer it is for the cable as it is better protected against hazards like fishing trawlers and the anchors of large vessels. If the water is any shallower than one kilometre, we tend to bury the cable under the sea floor to avoid damage.

2. Manufacturing. Submarine cable needs to be specially manufactured and only a few companies in the world have the both capability and location to do it – their base needs to be near a port with water deep enough for a large ship to enter so the cable can be loaded – in this case over 2,000km of it and it’s coiled just like your typical garden hose! There are two components to the cable – the optical fibres which carry light (i.e. data) and a plastic tubular cover to protect the fibre.

3. Laying. This is where the precision of the planning really comes into play. Out at sea, the ship’s crew use GPS co-ordinates to drop the cable into place. In some cases cables can be laid up to 9km deep. Just like a plow on the back of a farmer’s tractor, the cable is slowly released off the back of the ship using a joystick-like control device. When the crew get closer to shore, a directional bore is used to guide the cable from a manhole on land, under the shore line and out to sea. A dive team is usually on hand to help connect the two pieces of cable.

Our growing subsea network

While establishing a new submarine cable is a complicated and resource intensive task, it is central to enjoying the internet service so many people enjoy every day. Our global network is increasingly in demand and is the centerpiece of our growing international enterprise business. That is why we have been expanding our network. In addition to our stake in the TGA cable, we:

  • Recently built an overland fibre cable in Taiwan – a unique route from southern Taiwan to Hong Kong, which provides lower latency and diversity away from the earthquake prone Luzon Strait. This allows us to better service both the Taiwan market, and then beyond Taiwan to provide a unique redundancy link for traffic travelling from Japan and the US to Hong Kong and Singapore that other carriers cannot easily replicate.
  • Have acquired 1000Gbps capacity on the new 10,000km trans-pacific subsea “FASTER” cable system “FASTER” that connects Japan with the west coast of the US and makes use of 100Gbps wave technology. This enhances our network diversity and increases options for our customers.
  • Are enhancing our EAC-C2C cable, increasing capacity on the fibre pairs to 10 times their original design and extending the life of this cable by seven years until at least 2035 (at more than 36,000km this is the largest privately owned and operated cable in Asia).
  • Introduced a new highly resilient fibre ring network in South Korea, which brings new options and improved network resilience.

This network investment is critical to ensuring we can offer our customers around the world fast, resilient connection.