CoShare: An Efficient Approach for Redundancy Allocation in NFV
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An appealing feature of Network Function Virtualization (NFV) is that in an NFV-based network, a network function (NF) instance may be placed at any node. This, on the one hand, offers great flexibility in redundancy allocation to meet the availability requirements of flows; on the other hand, it makes the challenge unique and difficult. One particular highlight is that there is inherent correlation among nodes due to the structure of the network, implying that special care is needed for redundancy allocation in NFV-based networks. To this aim, a novel approach, called CoShare, is proposed. Originally, its design takes into consideration the effect of network structural dependency. In addition, to efficiently make use of resources, CoShare proposes the idea of shared reservation, where multiple flows may be allowed to share the same reserved backup capacity at an NF instance. Furthermore, CoShare factors in the heterogeneity in nodes, NF instances and availability requirements of flows in the design. The results from a number of experiments conducted using realistic network topologies show that CoShare is able to meet diverse availability requirements in a resource-efficient manner, requiring less resource overbuild than using the idea of dedicated reservation commonly adopted for redundancy allocation in NFV.
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