Disaster-Resilient Service Function Chain Embedding Based on Multi-Path Routing

By using virtualization technology, Network Function Virtualization (NFV) decouples the traditional Network Functions (NFs) from dedicated hardware, which allows the software to progress separately from the hardware. One of the major challenges for NFV deployment is to map Service Function Chains (SFCs), which are chains of sequenced Virtual Network Functions (VNFs), onto the physical network components. Meanwhile, network availability faces the threats of various natural disasters, one of which makes all network devices in the Disaster Zone (DZ) fail if it occurs. Thus, it is critical to establish an efficient disaster protection scheme for NFV deployment. In this paper, we introduce a novel disaster protection scheme for SFC embedding using multi-path routing. The major advantage of this scheme is to cut at least half of the reserved bandwidth on the backup path by balancing the SFC traffic load on multiple simultaneous DZ-disjoint working paths. The studied problem involves VNF entity placement, SFCs routing, content splitting and protection mechanisms. The objective is to minimize the network resource consumption, including bandwidth consumption for requests routing and computing resource for VNF execution. As we treat an optimization problem of multiple dimensions (i.e., NF placement, routing and protection), it is a challenging work to obtain the optimal solution. To this end, we propose a novel flow-based integer linear program (ILP) to model the SFC protection leveraging multi-path routing and the concept of layered graph. Numerical results demonstrate that our proposed multi-path based SFC protection strategy outperforms the traditional dedicated protection in terms of bandwidth and processing resources, saving up to 21.4% total network cost.