Disjoint end-to-end walks for Service Function Chain provisioning and protection

Service Function Chains (SFCs) enable traffic to flow through Virtual Network Functions (VNFs) deployed on physical servers to deliver network services. While SDN (Software Defined Network)/NFV (Network Function Virtualization) provides flexible network management, ensuring service continuity remains challenging and requires robust protection mechanisms.

Network failures can be addressed through local or end-to-end protection approaches. Local protection relies on multiple detours, potentially protecting against failures of the same components, which leads to complex management and multiple detour activations for single failures. End-to-end protection ensures service continuity through two end-to-end disjoint SFC provisioning paths, significantly reducing both route maintenance overhead and resource allocations.

This paper addresses the challenge of finding two end-to-end disjoint paths for SFC provisioning and protection. We first model the problem using ILP and prove its $\mathrm{NP}$-completeness, even in over-resourced networks where single SFC provisioning is polynomial-time solvable. To address this complexity, we propose a novel three-step heuristic that enhances protection through transient route computation that is intended to “leave room” and facilitate disjoint provisioning identification. Recomputation of the transient route is established to enhance the resource allocation while improving the protection efficiency. Our extensive simulations demonstrate significant improvements over conventional approaches, showing notable enhancement in both protection efficiency and SFC path quality without incurring additional costs.