Current views of restoration at the optical layer

Optical layer restoration has been the key driver behind the concept of optical networking. Indeed, the development of the SONET/SDH ring standards was based around the perception that 50 ms restoration in the case of a fiber event was essential. As bandwidth continues to be deployed, the core levels of the network are rapidly consuming multiple OC48 and OC192 channels. This implies that current SONET/SDH ring technology, excellent at managing and restoring an STS-1 fabric, will be stretched to its limit of usefulness. Continuing the argument, without carefully considering the changing nature of the bandwidth mix, leads one to conclude that the optical equivalent of a SONET BLSR employing WDM and OADM technologies will be the next stage of evolution