Survivable Virtual Network Mapping against Double-Link Failures Based on Virtual Network Capacity Sharing

Network Slicing is one of the key enabling technologies in 5G networks, as it allows the same network infrastructure to host numerous services, characterized by different Quality of Service (QoS) requirements. Network slicing provides greater flexibility when assigning resources to virtual networks (VNs, or, equivalently, "network slices"), allowing to meet very diverse service requirements. However, network slicing also brings numerous challenges in terms of management of network resources. Among these, service reliability is one of the most important, especially in light of the rising importance of ultra-reliable services in 5G. In this study, we investigate the Survivable Virtual Network Mapping (SVNM) problem focusing on double-link failures. SVNM against double-link failures can be guaranteed enforcing appropriate SVNM constraints, but this approach requires excessive redundant capacity.Capacity sharing represents a more capacity-efficient solution to ensure survivability against double-link failures. Hence, we propose a new SVNM strategy that allows capacity sharing across different virtual networks in case of double-link failure. To evaluate benefits of the proposed technique we categorize six different SVNM scenarios (with and without capacity sharing, jointly applied with SVNM or not) and formalize them through Integer Linear Programming (ILP) models. Results show that the proposed technique for SVNM with capacity sharing enables availability gains (up to about 29%) over traditional SVNM against single-link failures and significant capacity savings (up to about 50%) over SVNM against double-link failures. The advantages are more significant for increasing number of virtual networks.