Submarine  networking has long been—and, in many cases, still is—the unknown, yet critical,  part of the global Internet. Terrestrial networks (and, to a lesser extent, satellites)  have been the most visible networking cogs. Of course, terrestrial networks serve  as critical links, but they stop at the coastlines. And satellites carry a tiny  fraction of data traffic around the world.

The fact is, submarine  cables carry upwards of 99 percent of global Internet traffic between  continental landmasses. Current growth trends show no signs of letting up. With  channel capacity limits fast approaching and little appetite for adding cables,  how can submarine cable operators add sufficient submarine capacity to satisfy  insatiable demand?

About a decade  ago, the terrestrial fiber industry faced a similar situation. The technology  of the time—which used On-Off-Keying (OOK) to shutter a laser on and off to send  digital ones and zeros through an optical fiber—had its limitations, especially  when compared to current coherent optical transmission technology. Nonetheless,  it worked well at the time, and was able to maintain pace with relatively  modest demand growth.

But as broadband  took off with video and other bandwidth-intensive applications became increasingly  popular, the industry suddenly faced the immutable laws of physics—you can only  squeeze so many 10G channels into a single fiber pair.

Deploying more  terrestrial optical line systems was not always practical, and technologies  such as 40G were not yet realities. The industry had to face reality: it needed  to get more out of the fiber plants already deployed.

So the focus  turned to better utilizing the existing wavelength bands in the already  deployed fiber. Traditionally, fiber providers used the C-band, which runs from  approximately 1530nm to 1565nm. They were able to space numerous 10G channels very  close together through the fiber. But on very high-capacity and constrained  routes, this approach was quickly reaching its limits, so the industry started using  adjacent optical spectrum, known as the L-band, which runs from approximately 1565nm  to 1625nm.

Now, in yet another  example of technologies originally conceived in the terrestrial realm finding  their way beneath the seas, the submarine industry is looking to utilize L-band  to increase line capacity.

Vendors with  extensive L-band terrestrial network experience can take that existing  knowledge and real-world field experience to reliably adapt and incorporate L-band  modems into their existing Submarine Line Termination Equipment (SLTE) to  support both C-band and L-band, effectively doubling the available optical  spectrum and the addressable revenue along a submarine route. At the same time,  this combination offers greatly improved economies of scale. Expanding beyond  the C-band to the L-band also enables the introduction of new and differentiated  services based on Spectrum Sharing, which uses virtualization for the logical  partitioning of the optical spectrum in a submarine optical fiber pair between  different end-users. As such, each end-user sees only their dedicated ‘virtual’  fiber pair, which is a subset of the overall spectrum of the same, shared  physical fiber.

L-band, or long band, is a wavelength band immediately adjacent to the C-band that has been used for a decade to expand capacity of terrestrial networks. It is now being evaluated for use by submarine network providers.

How Ciena helps

Ciena, with  deep expertise in both terrestrial and submarine networks, enables submarine  cable operators to mix and match building blocks to create purpose-built  network solutions that can utilize both C-band and L-band. While adding that  flexibility, Ciena continues drive change in the closed and proprietary nature of  submarine networks. Submarine cable operators can now easily choose the best terminal  equipment technology for the right cost from any vendor.

Every day,  submarine cables carry more than US$10 trillion in transactions—the very  definition of critical infrastructure. Bandwidth consumption will grow at more  than 40 percent CAGR over the next few years in all regions. So utilizing a  solution like Ciena’s will enable submarine providers to get more out of their  existing infrastructure. Ciena’s GeoMesh Extreme helps you overcome the  challenges of submarine networks with four categories of available components—all  of which can be mixed and matched to address your specific business needs.

How GeoMesh Extreme is being used and  rolled out

Looking to expand  into L-band wavelengths, submarine cable operators are turning to GeoMesh  Extreme for its unique architecture that leverages both submarine and  terrestrial technologies. But GeoMesh Extreme also provides a wealth of  additional benefits to submarine networks, such as the analytics and machine  learning capabilities that come with a Software-Defined Network (SDN).

Other GeoMesh  Extreme features and services include:

  • SLA Portal, which dramatically improves customer  satisfaction and retention by providing transparent visualization of service  performance. Customers can self-diagnose network service health and verify SLA  performance assurance
  • PinPoint C-OTDR, which provides visibility into  the performance of multiple segments and systems of submerged plant. It also  enables remote access to C-OTDRs in various sites from a centralized NOC/data  center
  • Ciena’s Managed NOC services, which extend your  customers’ business with the networking skills and experience required to  manage their network infrastructure, provision bandwidth growth, and minimize  network downtime that impacts critical business processes
  • Network Health Predictor, which utilizes big  data analytics to enable you to proactively identify and address areas where  network issues and faults might occur
  • Topology Discovery, which ensures you can  utilize the network to maximum capacity by revealing actual network  connectivity, stitching circuits, and identifying stranded bandwidth
  • Alarm Correlation, which groups events to reduce  the number of issues you need to investigate. Because it identifies related  alarms and targets them simultaneously, you don’t spend as much time  troubleshooting