SDN/NFV control and orchestration system
The SDN/NFV control and orchestration system aims at providing global orchestration of the multi-layer (packet/optical) network resources and distributed cloud infrastructure resources. Macroscopically, it is composed of multiple elements that are arranged in a hierarchical setting:
Let us describe the different elements starting from a bottom- up approach.
For the optical layer, we adopted a deployment model that replies on a partial disaggregation. The control of the Open Line System (OLS) is decoupled from the control of the optical transceivers. In this sense, the photonic mesh network nodes (i.e., ROADMs and OXCs) are controlled with an Open Line Sytem (OLS) controller, implemented using an active stateful PCE (AS-PCE). It allows the provisioning of fixed- and flexi-grid data connectivity services (commonly network media channels at a variable frequency-slot widths). The OLS controller can use a diversity on South Bound Interfaces (SBI) such as NETCONF, RESTCONF or REST to configure the underlying devices. Services from tne OLS can be requested by an Optical Transport SDN controller, which also takes into account the configuration of the optical transceivers. In particular, by means of SDN agents, the S-BVT can be programmed and (re)-configured to adaptively transmit over the suitable optical network path. In addition, advanced (self)-performance monitoring is available on-demand in the platform. This functional element (named Optical Transport SDN Controller) can be implemented either extending the Open Source ONOS controller or via CTTC own implantation that follows the ABNO architecture. For the former, let us mention that it is also possible to deploy ONOS in such a way that it may directly configure the underlying devices, if they follow an open and standard device data model.
Optical and Packet Transport Layer
A second level of orchestration addresses the multi-domain and multi-layer aspects that characterized the optical and packet domains integration. This element, referred to as the end-to-end transport SDN Controller (also referred to as transport SDN orchestrator), is responsible for the end-to-end provisioning of connectivity services and delegates part of its functions to the children controllers.
The transport SDN orchestrator acts as a unified transport network operating system (or controller of controllers) that allows the control at a higher abstracted level, of heterogeneous network technologies regardless of the specific control plane technology employed in each domain through the use of the common Transport API. The Transport API enables to abstract a set of control plane functions used by an SDN controller. This abstraction enables network virtualization, that is, to partition the physical infrastructure and dynamically create, modify or delete multiple co-existing virtual tenant networks (VTN), independent of the underlying transport technology and network protocols. The SDN Orchestrator is also responsible for representing to the tenants an abstracted topology of each VTN (i.e., network discovery) and for enabling the control of the virtual network resources allocated to each VTN as if they were real.
NFV Service Platform and Network Slice Manager.
The NFV service platform follows the ETSI NFV Architecture, sitting on top of the multiple DC controllers to deploy general cloud services across distributed DC infrastructures (micro, small, core) resources for multiple tenants. Specifically, it allows to drive the creation/ migration/ deletion of VM/container (computing service), the storage of disk images (image service), and the management of the VM/container’s network interfaces (networking service) on the required DCs for each tenant. The ETSI NFV Management and Orchestration (MANO) architectural framework identifies three functional blocks; virtualized Infrastructure Manager (VIM), NFV Orchestrator (NFVO) and VNF Manager (VNFM). The VIM is responsible for controlling and managing the NFVI virtualized compute, storage and networking resources (e.g, Openstack controller). The VNFM is responsible for the lifecycle management (i.e., creation, configuration, and removal) of VNF instances running on top of virtual machines or containers. Finally, the NFVO has two main responsibilities, the orchestration of NFVI resources across multiple VIMs (resource orchestration), and the lifecycle management of network services (network service orchestration). We use open source MANO (OSM) and SONATA as NFVO.
The Network Slice Manager can dynamically provide service function chaining and NFV services and is responsible for the dynamic lifecycle management (provisioning, modification and deletion) of network slices. Each network slice is composed of virtual resources (VTN, computing and storage, and VNF) that exist in parallel and isolated for different tenants (e.g., vertical industries, virtual operators).