Protection Switching at the Physical Layer - Fast and Resilient

Automatic protection switching at the physical layer can greatly improve network resilience.  There are a number of small switches available, mainly based on PLC (Planar Lightwave Circuit) technology, which can handle simple "one for one" sparing of fibers or even 1:N protection.  However, the power of an optical matrix switch is the ability to enable rapid physical layer N for M protection switching.  In this concept, a pool of fibers can be shared between diverse routes and allocated automatically in response to a fiber path failure, as shown below.

 

The Polatis switch is ideal for this application because its low loss enables diverse routing through multiple nodes.  Integrated power monitors enable the system to automatically respond to loss of light without reference to a higher level control plane.  The Polatis technology does not require light on a fiber in order to hold a connection, so dark fiber routes can be pre-provisioned.  Combining this pre-provisioning capability with Polatis fast switching time enables the Polatis system to reconfigure a complete fiber network in approximately 20ms.