Posts

Showing posts with the label DWDM.

Primer on Optical Fibre & Subsea Versus Terrestrial Network Architecture

Image
Each fibre strand consists of the core and the cladding. The core is like a one way road for the light to traveland cladding are the guardrails that prevent it from escaping. The refractive index measures how fast light traverses a given medium. It is defined as the ratio of the speed of light in a vacuum to the velocity of light via the medium. The core has a higher refractive index than the cladding. As long as the refractive index differential is large enough, photons that hit the cladding at a critical angle or less will bounce back into the core. Physicists call this bouncing of light internal reflection. So the core/cladding structure is designed to preserve the optical power or amplitude of the wavelengths. It minimizes optical attenuation, the great enemy of optical networking along with chromatic and polar dispersion.  The bottom middle chart shows that optical attenuation, which reflects opposing forces, reaches a minimum in the C band. The C band is defined as wavelength...

The Marea Subsea Cable: A Pioneer Of The Open Cable Model And New TransAtlantic Routing

Image
Technology: Standard 100G wave coherent optics. Shorter repeater spacings to maximize per fibre pair throughput.  Fibre Pairs: 8.  Founding Fathers: Facebook and Microsoft Consortium Members: Facebook, Microsoft, and Telxius.  RFS: May, 2018.  Route: Direct Ashburn Equinix to Spain.  Landings: Virginia Beach, VA. Bilbao, Spain.  Notable Features: First cable to directly link Ashburn Equinix to Europe. Also first cable to adopt the open cable system model where each consortium member selects their own submarine line termination gear and owns either fibre pairs or spectrum.  Potential Throughput: 224 Tbps.  Marea is the first cable to give the cold shoulder to New York City and the UK. It directly links Ashburn Equinix via a Virginia Beach landing to Continental Europe with a Spanish landing. The cable completely bypasses the UK and the Northeastern US. This reflected Ashburn Equinix' rising importance and the desire of network planners  to avo...