Enabling Scalable and Sustainable Softwarized 5G Environments

The fifth generation of telecommunication systems (5G) is foreseen to play a fundamental role in our socio-economic growth by supporting various and radically new vertical applications (such as Industry 4.0, eHealth, Smart Cities/Electrical Grids, to name a few), as a one-fits-all technology that is enabled by emerging softwarization solutions \u2013 specifically, the Fog, Multi-access Edge Computing (MEC), Network Functions Virtualization (NFV) and Software-Defined Networking (SDN) paradigms. Notwithstanding the notable potential of the aforementioned technologies, a number of open issues still need to be addressed to ensure their complete rollout. This thesis is particularly developed towards addressing the scalability and sustainability issues in softwarized 5G environments through contributions in three research axes: a) Infrastructure Modeling and Analytics, b) Network Slicing and Mobility Management, and c) Network/Services Management and Control. The main contributions include a model-based analytics approach for real-time workload profiling and estimation of network key performance indicators (KPIs) in NFV infrastructures (NFVIs), as well as a SDN-based multi-clustering approach to scale geo-distributed virtual tenant networks (VTNs) and to support seamless user/service mobility; building on these, solutions to the problems of resource consolidation, service migration, and load balancing are also developed in the context of 5G. All in all, this generally entails the adoption of Stochastic Models, Mathematical Programming, Queueing Theory, Graph Theory and Team Theory principles, in the context of Green Networking, NFV and SDN

Joint Power Scaling of Processing Resources and Consolidation of Virtual Network Functions

With the advent of network 'softwarization', Network Functions Virtualization (NFV) is foreseen to provide flexibility and programmability levels that would essentially help in coping with tomorrow's demands. However, energy efficiency and the resulting complexity of network/service management pose serious sustainability and scalability issues that may hinder NFV's advantages. This paper considers these aspects in the context of datacenter networks. We propose an energy-Aware resource allocation scheme to manage virtual machines, dedicated to perform certain (virtualized) network functions, among a pool of energy-Tunable physical resources (processors/cores). We use online measurements to periodically estimate some statistical features of the offered workloads by considering a fairly general renewal model that captures traffic bustiness and hardware operational settings. Then, resources are dynamically managed by jointly performing power scaling and in-server consolidation according to the actual workload variations. The average power consumption generated by this strategy is evaluated and compared with that of a classical bin-packing consolidation, over processors running always with the highest-performance configuration. Results show that the proposed approach can reduce the average power consumption of the datacenter by up to 10%, suggesting a considerable amount of annual savings

Move with Me: Scalably keeping virtual objects close to users on the move

The upcoming Cloud-Fog interplay is expected to grant service providers more degrees of freedom in the implementation and management of their service portfolios. However, recent advances in Mobile Internet have developed a growing need to support user mobility - as users move, the Fog counterparts of services that require close proximity may call for migration(s) to meet the desired quality of service (QoS). With the state-of-the-art virtualization technologies, next-generation Cloud/Fog services are being implemented in modular software (i.e., as a graph/chain of portable virtual objects (VOs)) that can be migrated around the Telco infrastructure, and yet scalability is still an open issue, especially with the inter-datacenter bulk live migration of VOs. In this perspective, a VO clustering and migration policy that jointly considers user proximity and inter-VO affinity is proposed to scalably support user mobility, while allowing service differentiation among users. Results confirm that introducing migrations improve the QoS to always meet or exceed the requirements, as compared to static service placement, and considering VO clusters as aggregate entities will initiate around 40% less migrations, on average - an improvement that increases with inter-VO affinity and could potentially simplify service management when supporting user mobility

A scalable SDN slicing scheme for multi-domain fog/cloud services

By bringing Cloud-like services much closer to endusers and their devices, Fog computing is foreseen to expand the scope of overlay networks, encompassing different heterogeneity dimensions (i.e., size, geographical distribution, devices/virtual objects (VOs) involved, quality of service (QoS) requirements, etc.). Although highly flexible solutions like Software-Defined Networking (SDN) have been conceived to handle such heterogeneity in future networks, scalability is still an open issue, especially with respect to Fog computing requirements. In this paper, we propose an SDN-based network slicing scheme for supporting multi-domain Fog/Cloud services, which offers high scalability, among other aspects, over legacy ones. Results show that the number of unicast forwarding rules needed to be installed in an overlay drops by up to over one order of magnitude and 4 times compared to the "fully-meshed" and OpenStack cases, respectively, at the cost of possible path sub-optimality, albeit knowledge on the datacenter topology can be used for VO placement optimization

Decentralized Scalable Dynamic Load Balancing among Virtual Network Slice Instantiations

In the virtualized environment of 5G networks, the control and management of dynamic network slices poses a set of challenges that are still largely unsolved. Though the architectural framework and the elements of abstraction and orchestration mechanisms have been defined, the dynamic orchestration of resources based on them entails the adoption of existing sophisticated control techniques, or the design of new ones for the specific environment. In the present paper, we address the problem of load balancing among multiple network service chains (which represent network slice instantiations of a Network Service Provider referring to a specific vertical application) originating from different Points of Presence (PoPs). For scalability reasons, we want to maintain the problem within an informationally decentralized setting, where each PoP has the knowledge of the aggregate workload generated by the slice users accessing through it, but not of that of the other PoPs (to avoid the exchange of information for control purposes). By taking also into account power consumption policies of the Infrastructure Provider, we find a set of candidate team-optimal solutions to this load-balancing problem, which are characterized by piecewise-linear functions, and compare their performance with that of other resource allocation strategies

A Multi-Clustering Approach to Scale Distributed Tenant Networks for Mobile Edge Computing

Fifth generation (5G) mobile networks will lead to a deep integration between networks and applications. Through novel paradigms like Network Functions Virtualization (NFV) and Edge Computing, new classes of heterogeneous application services will be enabled to run close to mobile end-user devices with zero-perceived latency and fully-cognitive dynamic reconfiguration capabilities. Such \u201cvertical\u201d applications exhibit diverse performance/scalability requirements, and will rely on highly distributed, extremely virtualized, multi-tenant and software-defined infrastructures. In such context, handling the required operations in a scalable and dynamic fashion will be of paramount importance. A specific aspect, addressed by Software Defined Networking (SDN), regards the provision of suitable communication channels, once resource allocation mechanisms have performed the most efficient deployment of Virtual Network Function (VNF) instances, and VNF chaining needs to be implemented to enable network services. In this respect, this paper introduces the Multi-Cluster Overlay (MCO) network paradigm: a tunnel-less SDN scheme for scalable realization of Virtual Tenant Networks (VTNs) across the 5G distributed infrastructure, able to support (bulk) migrations of software instances among geo-distributed computing resources in a seamless and effective fashion. Numerical simulation and experimental results show that the MCO achieves up to over one order of magnitude smaller number of forwarding rules than other state-of-the-art SDN mechanisms, while also assuring high performance during reconfiguration operations

A Model-based Approach Towards Real-time Analytics in NFV Infrastructures

none4Network Functions Virtualization (NFV) has recently gained much popularity in the research scene for the flexibility and programmability that it will bring with the software implementation of network functions on commercial off-the-shelf (COTS) hardware. To substantiate its roll out, a number of issues (e.g., COTS' inherent performance and energy efficiency, virtualization overhead, etc.) must be addressed, in a scalable and sustainable manner. Numerous works in the scientific literature manifest the strong correlation of network key performance indicators (KPIs) with the burstiness of the traffic. This paper proposes a novel model-based analytics approach for profiling virtualized network function (VNF) workloads, towards real-time estimation of network KPIs (specifically, power and latency), based on an MX/G/1/SET queueing model that captures both the workload burstiness and system setup times (caused by interrupt coalescing and power management actions). Experimental results show good estimation accuracies for both VNF workload profiling and network KPI estimation, with respect to the input traffic and actual measurements, respectively. This demonstrates that the proposed approach can be a powerful tool for scalable and sustainable network/service management and orchestration.noneRaffaele Bolla, Roberto Bruschi, Franco Davoli, Jane Frances PajoBolla, Raffaele; Bruschi, Roberto; Davoli, Franco; Pajo, JANE FRANCE

Load dynamics of a multiplayer online battle arena and simulative assessment of edge server placements

Free-to-play models, streaming of games and eSports are reasons for online gaming to grow in popularity recently. On the forefront are multiplayer online battle arenas, which gain high popularity by introducing a competitive format that is easy to access and requires cooperation and team play. These games highly rely on fast reaction of the players, which makes latency the key performance indicator of such applications. To obtain low latency, this paper proposes moving game servers close to players towards the edge of the network. The performance of such mechanism highly depends on the geographic distribution of players. By analyzing match histories and statistics, we develop models for the arrival process and location of game requests. This allows us to evaluate the performance of edge server resource migration policies in an event based simulation. Our results show that a high number of edge servers is preferable compared to few larger edge servers to reduce the latency of players. This supports approaches that allow deploying virtual server instances in the back-haul