Efficiency gains due to network function sharing in CDN-as-a-Service slicing scenarios

Proceedings of: IEEE 7th International Conference on Network Softwarization (NetSoft), 28 June-2 July 2021, Tokyo, Japan.The consumption of video contents is currently dominating the traffic observed in ISP networks. The distribution of that content is usually performed leveraging on CDN caches storing and delivering multimedia. The advent of virtualization is bringing attention to the CDN as use case for virtualizing the cache function. In parallel, there is a trend on sharing network infrastructures as a way of reducing deployment costs by ISPs. Then, an interesting scenario emerges when considering the possibility of sharing virtualized cache functions among ISPs sharing a common physical infrastructure, mostly considering that usually those ISPs offer similar content catalogues to final end users. This paper investigates through simulations the potential efficiencies that can be achieved when sharing a virtual cache function if compared to the classical approach of independent virtual caches operated per ISP.This work has been partly funded by the project 5GROWTH (Grant Agreement no. 856709)

Service Deployment Model on Shared Virtual Network Functions With Flow Partition

Network operators can operate services in a flexible way with virtual network functions thanks to the network function virtualization technology. Flow partition allows aggregated traffic to be split into multiple parts, which increases the flexibility. This paper proposes a service deployment model with flow partition to minimize the service deployment cost with meeting service delay requirements. A virtual network function of a service is allowed to have several instances, each of which hosts a part of flows and can be shared among different services, to reduce the initial and proportional cost. We provide the mathematical formulation for the proposed model and transform it to a special case as a mixed integer second-order cone programming (MISOCP) problem. A heuristic algorithm, which is called a flow partition heuristic (FPH), is introduced to solve the original problem in practical time by decomposing it into several steps; each step handles a convex problem. We compare the performances of proposed model with flow partition and conventional model without flow partition. We consider the formulated MISOCP problem with adopting a strategy of even splitting to divide flows in a special case, which is called an even spitting heuristic (ESH). The performances of FPH and ESH are compared in a realistic scenario. We also consider the formulated MISOCP problem as an original problem and compare it to an FPH-based heuristic algorithm with the even-splitting strategy (FPH-ES), in both realistic and synthetic scenarios. The numerical results reveal that the proposed model saves the service deployment cost compared to the conventional one. It improves the maximum admissible traffic scale by 23% in average in our examined cases. We observe that FPH outperforms ESH and ESH outperforms FPH-ES in terms of the service deployment cost in their own focused problems, respectively

Reducing Service Deployment Cost Through VNF Sharing

Thanks to its computational and forwarding capabilities, the mobile network infrastructure can support several third-party (“vertical”) services, each composed of a graph of virtual (network) functions (VNFs). Importantly, one or more VNFs are often common to multiple services, thus the services deployment cost could be reduced by letting the services share the same VNF instance instead of devoting a separate instance to each service. By doing that, however, it is critical that the target KPI (key performance indicators) of all services are met. To this end, we study the VNF sharing problem and make decisions on 1) when sharing VNFs among multiple services is possible, 2) how to adapt the virtual machines running the shared VNFs to the combined load of the assigned services, and 3) how to prioritize the services traffic within shared VNFs. All decisions aim to minimize the cost for the mobile operator, subject to requirements on end-to-end service performance, e.g., total delay. Notably, we show that the aforementioned priorities should be managed dynamically and vary across VNFs. We then propose the FlexShare algorithm to provide near-optimal VNF-sharing and priority assignment decisions in polynomial time. We prove that FlexShare is within a constant factor from the optimum and, using real-world VNF graphs, we show that it consistently outperforms baseline solutions.This work was supported by the EU Commission through the 5GROWTH project (grant agreement no. 856709). The work of G. Scalosub has been supported by the Israel Science Foundation (grant No. 1036/14) and the Neptune Consortium, administered by the Israeli Ministry of Economy and Industry