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 data-center resources. While this joint optimization is becoming increasingly common even at the optical layer, some aspects of the dimensioning remain siloed between the network/IT worlds. Survivability mechanisms are one such example, where protection for lightpaths and/or 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.