Resilient VNF Placement for Service Chain Embedding in Diversified 5G Network Slices

A 5G network slice is comprised of several service chains (SCs) - a chain of virtualized network functions (VNFs) each performing a function (e.g., firewall) to serve diverse traffic requirements. These VNFs are hosted on servers/physicalmachines in one or more data-centers. In this context, a fault/attack on a 5G network could be as fine grained as a VNF failure or as coarse-grained as the failure of a hosting physicalmachine (PM). The latter may lead to multiple VNF failures that may affect several SCs in one or more network slices. To enable resilience towards such failure/attacks, one approach is to protect all the SCs by replicating the VNFs on different PMs. However, such a protection approach will significantly increase the computational and operational costs opposing the 5G network objective. In this paper, we propose an approach for resilient network slice embedding such that the VNFs of a service chain are instantiated on appropriate PMs to minimize the number of affected SCs upon a PM failure. We develop an optimization programming formulation that minimizes the maximum of the affected number of weighted service chains while satisfying the VNF placement and routing constraints in the co located 5G network slices along with resource (bandwidth, computing) and slice-specific requirements. We evaluate the proposed resilient mapping approach through numerical analysis and show that it achieves a resilience factor of up to 0.88 while requiring 78% less number of VNF replicas on an average, when compared to the protection-based approach.