Submarine networks carry more than 95 percent of the world’s intercontinental electronic communications traffic and are responsible for over $10 trillion worth of transitions every day. They are the backbone of the internet, but simply have not received the same media attention as counterparts on land or in space.
Traditionally, submarine networks have been managed manually with offline tools such as ledgers and spreadsheets. Most operators today use some type of network management system software, with a growing adoption and integration of automation and analytics. Automation allows operators to select service path endpoints and the network automatically provisions the service – something that in the past would have taken days to months now takes only minutes, maybe even seconds. Plus, because this involves machine-to-machine communications, the chances of an error are significantly reduced, making the process quicker and more secure. Analytics allows for understanding the health of the network on an ongoing basis and proactively and reactively choosing the best path for a service across the network.
Data traffic is expected to grow significantly in the coming years, with bandwidth increasing around the world. There is no sign that this growth will slow down anytime soon. The increase in traffic is in part due to some of the more obvious offenders – just look around and you can’t help but notice the number of people glued to their phones consuming videos and playing games. Also, as developing countries continue to have access to and embrace technology, the amount of traffic will grow by leaps and bounds. And not so obvious, but right now one of the biggest culprits is machine-to-machine traffic between data centers where accessed content is hosted and shared. Some of these bits will travel between data centers over land, but others will make the long jump across the ocean, moving through fiber optic cables on the seafloor.
No matter where the traffic is coming from, the enormous growth in bandwidth demand is pushing the technology that enables submarine networks to the limit, requiring innovations in all parts of the end-to-end network, from data center to data center.
We’re approaching Shannon’s Limit in the submarine cable industry, getting close to how much information we can send down an individual optical fiber. Shannon’s Limit effects every type of communications, whether you’re a wireless carrier or submarine cable operator – there’s a limit to the amount of information you can share through a particular communications medium.
About ten years ago, coherent technology came into the submarine cable market and it’s now the standard to upgrade any subsea cable. As the bandwidth continues to grow, coherent modems are the technology of choice and the industry keeps developing technologies, such as improved forward error correction, linear and non-linear mitigation techniques, and so on. Once we hit that maximum limit on the fiber, we’ll have to deploy more submarine cables, which may likely be based on Spatial Division Multiplexing (SDM) offering significantly more fiber pairs than existing subsea cables.
Adopting coherent technology allows submarine network operators to significantly increase bandwidth capacity far higher than initial total design capacities. One of the key attributes of coherent optical technology is the high coding gain, soft-decision Forward Error Correction (FEC), which enables signals to travel longer distances, while requiring fewer regenerator points. This provides a wider margin, allowing higher bit-rate signals to traverse greater distances – increasing bandwidth significantly while simplifying photonic lines, requiring less equipment and lowering costs. A variety of impairment mitigation techniques incorporated into DSP technology has also enabled massive capacity increased on both old and new submarine cables.
Analytics can uncover trends in a network and help address failures before they occur by determining what is “normal” and what is “not normal” through the ongoing analysis of streaming network sensor data. Analytics provides actionable insights so that operators can address potential issues proactively rather than reactively. Having this insight is the first step in creating a network that is capable of identifying its own weaknesses, and automatically adjusting without human involvement.
By Brian Lavallée, senior director at Ciena