Optical Networks Virtualization and Slicing in the 5G era
Ricard Vilalta, Arturo Mayoral López-de-Lerma, Raül Muñoz, Ricardo Martínez, Ramon Casellas · Optical Fiber Communication Conference · 2018
We provide an overview of operationalization and deployment of the different data and control plane technologies used for both Optical Network Virtualization and Network Slicing, which are two key enablers of future 5G networks.OCIS codes: (060.4250)Networks; (060.4510)Optical communications IntroductionFuture 5G networks will support a wide range of services and use cases arising from different vertical industries (e.g., IoT, eHealth, Industry4.0,etc.).Each of these services / business cases impose their own set of requirements to the network infrastructure, in terms of security, latency, elasticity, resiliency, and bandwidth.To deal with these challenges, the NGMN proposed the concept of network slicing (NS).Briefly, a network slice instance is formed by a set of network functions, and the resources enabling the deployment of these functions, forming a complete instantiated logical network to meet certain network characteristics for a specific service.Optical Network Virtualization is a key enabler for network slicing, as it provides the necessary technologies to provide the specified set of network requirements, while providing the necessary isolation between network slices.In this paper, we will review the suggested technologies from both data and control plane perspectives.Moreover, the authors have proposed and presented candidate architectures aiming at combining NS with transport networks.In this regard, [1] focused on an experimental demonstration of a multi-tenant network slicing architecture that besides dynamically deploying 5G slices (encompassing virtual network and cloud resources, and virtualized network functions), it deploys dedicated SDN/NFV control plane instances for each slice enabling full control of the allocated resources.In [2], cascading of network and cloud resources was proposed as the recursive hierarchical abstraction and virtualization of resources.We have analyzed the current trends for NS [3][4], where a slice manager is introduced in order to interact with a resource orchestrator.This paper presents a novel architecture to both support multi-tenancy and NS on top of interconnected multiple NFVI-PoPs.Each tenant will be able to run a dedicated Service Platform (NFV-O + VNFM), which might be deployed on top of the shared infrastructure Despite the expected benefits provided by adopting SDN/NFV technologies, a number of issues to cope need to be bypassed.In this sense, some of the most significant difficulties are: the need for interoperability between VNFs and orchestrators (which is being reduced through the open source software community), the combination of SDN and NFV technologies (e.g., lack of flexible support for end-to-end multi-site installations), and the consolidation of the initiatives to avoid the "additional development needed" to integrate the application/service on the platform.In order to mitigate these difficulties, we propose a model introducing DevOps for Networking. (Optical) Network VirtualizationOptical network virtualization (ONV) refers to the partitioning and aggregation of the physical optical infrastructure to create multiple co-existing and independent virtual networks (VN) on top of it.ONV can be introduced at data plane with enabling technologies which support virtualization (packet or circuit based), or with resource virtualization at the control plane level [5].The usage of such virtualization technologies in NS might accomplish benefits in terms of security, latency, elasticity, resiliency, and bandwidth.At the data plane, network virtualization can be performed differently according to the considered layer (Fig. 1.a).At the Layer 0, dedicated physical interfaces, wavelengths, cores and modes might be allocated to a VN.At layer 1, OTN tunnels can be considered.At the Layer 2, MPLS and FlexEthernet connections can be adopted.Later, the use of VLANs allows creating up to 4094 virtual networks over the same physical Ethernet interfaces.At the Layer 3, the composition of overlay networks through tunneling mechanisms (e.g., NVGRE, NSH) provides the necessary VN.From the control plane perspective, several initiatives are currently addressing the ONV framework.In OIF, a Virtual Transport Network Service (VTNS) is the creation and offering of a VN by a provider to a user [6].VNs may be dynamically created, deleted, or modified and users can perform connection management, monitoring and protection within their allocated VNs.Different types of VTNS could be associated to operators offering, for example, Bandwidth on Demand (BoD) services, Network as a Service (NaaS) or Network Slicing for 5G Networking.In IETF, the Abstraction and Control of Traffic Engineered Networks (ACTN) architecture [7] defines the requirements, use cases, and an SDN-based architecture, relying on the concepts of network and service abstraction.