considering operator constraints: protection and Qos
A critical issue when dealing with optical transport networks is their resiliency,since a failure of a single fiber link produces the breakdown of several traffic demands, carrying large amounts of data flows, In order to avoid this and to provide an acceptable QoS level to the end-users, network resiliency is typically achieved through a dedicated protection 1+1 scheme, where data is first duplicated and then transmitted onto two different link-disjoint paths. This requires the deployment of redundant devices and, consequently, increases the power consumed by the network, since both have to be active on the working and protection paths.
when accomplishing network design and operation of resilient networks, several strategies can be adopted to enable at the same time energy-efficient networking. Among these,we can take into consideration the load-proportional solutions described in section IV,e.g., the possibility of setting unused/protection resources in low-power sleep state, as well as the devices rate-adaptation to the traffic dynamics. Furthermore, as high protection degree could be unnecessary for some kinds of services, a more power power-friendly strategy, based on a differentiated Quality of protection(QoP) scheme, can be exploited so that a lower number of redundant resources are utilized,To this scope, some demands can be