Riccardo Guerzoni

SDN-based 5G mobile networks: architecture, functions, procedures and backward compatibility

In this paper, we describe an SDN-based plastic architecture for 5G networks, designed to fulfill functional and performance requirements of new generation services and devices. The 5G logical architecture is presented in detail, and key procedures for dynamic control plane instantiation, device attachment, and service request and mobility management are specified. Key feature of the proposed architecture is flexibility, needed to support efficiently a heterogeneous set of services, including Machine Type Communication, Vehicle to X and Internet of Things traffic. These applications are imposing challenging targets, in terms of end-to-end latency, dependability, reliability and scalability. Additionally, backward compatibility with legacy systems is guaranteed by the proposed solution, and Control Plane and Data Plane are fully decoupled. The three levels of unified signaling unify Access, Non-access and Management strata, and a clean-slate forwarding layer, designed according to the software defined networking principle, replaces tunneling protocols for carrier grade mobility. Copyright

A novel approach to virtual networks embedding for SDN management and orchestration

The development of methodologies to manage and orchestrate virtualised resources and network functions is a fundamental enabler for optimally utilising physical ICT infrastructures. Algorithms for optimal location (embedding) of network functions, IT and CT resources, services and corresponding states, especially at the network edge, will enable new business models and provide a key competitive advantage to network administrators. This paper introduces a novel Mixed Integer Programming (MIP) formulation for a coordinated node and link mapping onto the underlying network infrastructure. Extensive simulation results show that the proposed algorithm outperforms prior art formulations: two digit gains were attained in terms of resources utilisation, embedding, revenues and, especially convergence time. The proposed methodology is applicable to a number of relevant use cases, as constraints and objective functions can be flexibly defined by network operators.

Virtual Links Mapping in Future SDN-Enabled Networks

Software defined networking (SDN) has emerged as an efficient network technology for lowering operating costs through simplified hardware, software and management. Specific research focus has been placed to achieve a successful carrier grade network with SDN, in terms of scalability, reliability, QoS and service management. In the literature, very little material is currently available on traffic engineering (TE) using this technology. This paper presents a novel mixed integer linear programming (MILP) formulation for a centralised controller to calculate optimal end-to-end virtual paths over the underlying network infrastructure, considering multiple requests simultaneously. Extensive simulation results, over a wide range of underlying network topologies and input parameters, demonstrate that the proposed algorithm outperforms traditional shortest path first (SPF) approaches. In some cases, up to 30 % more virtual connections were satisfactorily mapped onto the same substrate, independent of the number of physical nodes.

On end to end network slicing for 5G communication systems

The heterogeneity in use cases and the need to support diverse requirements from vertical markets are the main drivers for new design principles of 5G communication systems. In this paper, we review the notion of plastic architecture and propose an end to end network slicing concept to serve new 5G capabilities and features in a flexible and efficient manner. Besides the concept definition, we address in particular the key issue of how 5G devices may be enabled to discover, select and access the most appropriate E2E network slices. To solve the issue, we developed a novel Device Triggered Network Control mechanism and evaluated its performance and implementation cost with respect to alternative available schemes, where the slicing concept was applied only to the core network domain of the communication system. Simulation results showed two digits gains in terms of attachment delay and signalling overhead. Copyright

Recursive, hierarchical embedding of virtual infrastructure in multi-domain substrates

One of the main goals of future telecom networks is to achieve softwarization of network functions. A requirement to achieve this softwarization is the ability to construct on-demand networks across multi-domain network and/or cloud service providers (NCSP). Most current algorithms and MILP formulations that solve the multi-domain embedding problem work on a flat infrastructure using simplified physical resource models. In this paper we propose an abstraction of the physical network domains to make the multiple domains appear as a pseudo flat infrastructure enabling re-use of existing flat infrastructure embedding algorithms with a few modifications. We incorporate these modifications in our previously proposed embedding ILP formulation. Our results show that we can speed up the process of embedding in large multi-domain networks considerably while trading off some efficiency in resource utilization due to abstraction.

Network Resource Management and QoS in SDN-Enabled 5G Systems

Virtual Network Embedding (VNE) is considered a key technology to instantiate and operate Data and Control planes in next generation (5G) SDN-based Networks. Within this domain, Network Resource Management (NRM) is an essential feature to allow efficient resource utilisation, to enable network slicing and to guarantee fairness among the supported QoS classes. This paper presents and evaluates three alternative NRM policies: Full Sharing, Full Split and Russian Dolls. Policies define how different QoS classes share the available bandwidth on per link basis. The policies have been integrated in a MIP-based Virtual Link Mapping formulation (VLM+) supporting multi-constrained end to end QoS. Simulation results show different policies can suit different network operators requirements. Also, results highlight Russian Dolls significantly outperforms other policies in terms of Embedding Rate and Link Utilisation, still preserving fairness among QoS Classes. VLM+ Convergence Time has also been evaluated, showing all policies are compatible with timing requirements for a real 5G system implementation.

Orchestration of Crosshaul slices from federated administrative domains

With the advent of 5G networks, more dynamicity and flexibility will be needed for the deployment of services with very distinct requirements. Crosshaul areas (those integrating fronthaul and backhaul) are especially critical because of the variability of the demand and the cost of the (own) network deployment, which in many cases is jeopardized by the huge level of investment needed. A common market place to trade the required networking and computing facilities (in the form of a slice) in a multi-domain federated environment is envisaged as the solution for easing the adaptation to future demands. This paper proposes to develop the concept of multi-domain Crosshaul by enabling the dynamic request of Crosshaul slices through a multi-provider exchange.

Modeling Reliability Requirements in Coordinated Node and Link Mapping

High performance systems require high levels of reliability. Many functions involved in telecommunication and IT networks have reliability requirements that can only be achieved by introducing redundant resources. In the telecom sector, recently, there has been a significant effort on moving carrier grade systems and functions to virtualized network infrastructure. The management and coordination of those virtualized systems to achieve an optimal mapping (or embedding) to the physical resources that host them is known as virtual resource orchestration. In our prior work we introduced a novel model, based on Mixed Integer Programming (MIP) problem formulation, as one significant way of achieving this optimality in embedding. This paper extends the model to include reliability requirements, improving prior art techniques as well as implementing a novel approach, denoted as reliability assurance. The confidence of the target reliability of the embedded virtual graphs can be traded with the efficiency of the substrate utilization. Extensive simulation results show that our model provides embedding rates and infrastructure utilization comparable with prior art while fulfilling high reliability requirements.

On optimal hierarchical SDN

To address scalability concerns, hierarchical control plane organization has been proposed for SDN. However, an open question is how such a hierarchy should look like. In this paper, we model the impact of hierarchies on control plane performance and derive an expression for an optimal hierarchical organization for a given network scale. We then show that using a 4-layer SDN is sufficient for practical network scales, suggesting feasibility and relevance of this approach. Finally, we illustrate the elasticity of hierarchical SDN, which enables a more flexible cost evolution of the SDN control plane.

Towards zero latency Software Defined 5G Networks

This paper presents a novel SDN-based 5G network architecture, conceived to support next generation delay critical services. Following a 4G systems delay analysis, new design principles towards a “zero latency” network are discussed. Based on these guidelines, and under the assumption of a broad adoption of emerging SDN and NFV technologies, a novel “plastic” architecture for 5G systems is devised. Together with the architecture, new procedures for device attachment, connectivity and mobility management are presented. Latency improvements from the proposed architecture have been estimated up to 75% compared to 3GPP Release 12 compliant 4G systems.