Hybrid Backup Resource Optimization for VNF Placement Over Optical Transport Networks The concept of edge computing is vital in the 5G ecosystem, as a means of introducing application awareness in the network and enabling constructs such as slicing to be effectively implemented. In this scope, an efficient infrastructure dimensioning requires visibility of both network and datacenter resources. While this joint optimization is becoming increasingly common even at the optical layer, some aspects of the dimensioning remain siloed between the networkIT worlds. Survivability mechanisms are one such example, where protection for lightpaths andor virtual network functions (VNFs) is typically provisioned independently, potentially incurring in resource overprovisioning. This paper investigates the merits of exploiting a hybrid strategy where backup resources are selectively distributed between the IT and optical layers in metro ring scenarios, according to specific service requirements such as latency and bandwidth. Critically, this analysis incorporates, through an integer linear programming (ILP) model, the effect of optical path performance on the cost efficiency of protection mechanisms, which is shown to greatly influence the optimal resource distribution in each deployment scenario.

Survivability in optical networks: a solution for the wavelength continuity constraint case Survivability of internet services is a significant and crucial challenge in designing future optical networks. A robust infrastructure and transmission protocols are needed to handle such a situation so that the network users can maintain communication despite the existence of one or more failed components on the network. For this reason, in this work, we present a generalized approach to tolerate any set of failure scenarios, to the extent the user can still communicate with the remaining components, where a scenario corresponds to an arbitrary set of links in a nonoperational state. To assess the survivability problem, we propose a joint solution to the problems listed next. We show how to find: a set of primary routes, a set of alternate routes associated to each failure scenario, and the capacity required on the network to allow communication between all users, in spite of any failure scenario, while satisfying for each user a specific predefined quality of service threshold, defined in the Service Level Agreement (SLA). Numerical results show that the proposed approach not only enjoys the advantages of low complexity and ease of implementation but is also able to achieve significant resource savings compared to existing methods. The savings are higher than 30% on single link failures and more than a 100% on two simultaneous link failures scenarios and in more complex failure scenarios.