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MSO High-level System Architecture
See the attached presentation for an explanation of the system architecture of MSO, and its interaction with other ONAP components: MSO High-level Design.
MSO Overview
ONAP orchestration arranges, sequences, and implements tasks based on rules and policies to coordinate the creation, modification, or removal of network, application or infrastructure services and resourceslogical and physical resources in the managed environment. The Master Service Orchestrator (MSO) manages orchestration at the top level and facilitates additional orchestration that takes place within underlying controllers. It also marshals data between the various controllers so that the process steps and components required for execution of a task or service are available when needed.
The MSO subsystem runs autonomously within OpenECOMP. Orchestration provides adaptability and flexibility. OpenECOMP's combination of orchestration and policies can be used to create flexible processes that are guided by business and technical policies and driven by process designers.
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Orchestration exists throughout the D2 architecture and should not be limited to the constraints implied by the term “workflow” as it typically implies some degree of human intervention. Orchestration in D2 will not involve human intervention/decision/ guidance in the vast majority of cases. The human involvement in orchestration is typically performed up front in the design process although there may be processes that will require intervention or alternate action such as exception or fallout processing.To support the large number of Orchestration requests, the orchestration engine will be exposed as a reusable service. With this approach, any component of the architecture can execute process recipes. Orchestration Services will be capable of consuming a process recipe and executing against it to completion. The Service model maintains consistency and reusability across all orchestration activities and ensures consistent methods, structure and version of the workflow execution environment.
Orchestration Services will expose a common set of APIs to drive consistency across the interaction of ECOMP components. To maintain consistency across the platform, orchestration processes will interact with other platform components or external systems via standard and well-defined APIs.
The Master Service Orchestrator’s (MSO’s) primary function is the automation of end-to-end service instance provisioning activities. The MSO is responsible for the instantiation /and release, and subsequent migration /and relocation of VNFs in support of overall ECOMP end-to-end service instantiation, operations and management. The MSO executes well-defined processes to complete its objectives and is typically triggered by the receipt of ‘service requests’ service requests generated by other ECOMP ONAP components or by Order by Order Lifecycle Management in Management in the BSS layer. The orchestration “recipe” procedure is obtained from the Service Design and Creation (ASDCSDC) component of the ECOMP Platform ONAP, where all Service Designs service designs are created and exposed/distributed for consumption.
Controllers (Infrastructure, MSO runs autonomously within ONAP.
The orchestration engine is a reusable service. Any component of the architecture can execute process workflows. Orchestration services can consume a process workflow and execute it. The service model maintains consistency and reusability across all orchestration activities and ensures consistent methods, structure and version of the workflow execution environment.
Orchestration processes interact with other platform components or external systems via standard and well-defined APIs.
Controllers (Network and Application) participate in service instantiation and are the primary players in ongoing service management, e.g.; for example, control loop actions, service migration /and scaling, service configuration, and service management activities. Each Controller controller instance supports some form of orchestration to manage operations within its scope.
Figure 10 illustrates the use of Orchestration in the two main areas: Service Orchestration embodied in the Master Service Orchestrator and Service Control embodied in the Infrastructure, Application and Network Controllers. It illustrates the two major domains of D2 that employ orchestration1 shows the two major domains that use orchestration: service orchestration, which is embodied in MSO and service control, which is embodied in the Application and Network Controllers. Although the objectives and scope of the domains vary, they both follow a consistent model for the definition and execution of orchestration activities.
Figure 1. Orchestration
Depending on the scope of a network issue,
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MSO may delegate, or a
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controller may assume, some of the activities identified
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in Figure 1. For new services, this may involve determination of service placement and identification of existing controllers that meet the Service Request parameters and have the required capacity. If existing controllers
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do not exist or do not have capacity,
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MSO will obtain a
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procedure for instantiation of a new
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controller under which the requested
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service can be placed.
ASDC is the module of ECOMP where orchestration In future releases Orchestration process flows are definedwill be defined in the Service Design and Creation subsystem (SDC). These process flows will start with a template that may include common functions such as homing determination, selection of Infrastructure, Network network and Application Controllersapplication controllers, consultation of policies and interrogation of A&AI Active and Available Inventory (AAI) to obtain necessary information needed to guide the process flows. The MSO does not provide any process-based functionality without a recipe workflow for the requested activity regardless of whether that request is a Customer Order or a Service adjustment/ configuration update to an existing service. MSO will interrogate A&AI (in the current release the process flows are designed directly in MSO using BPMN flows).
MSO interrogates AAI to obtain information regarding existing Network and Application Controllers to support a Service Request. A&AI will provide service request. AAI provides the addresses of candidate Controllers controllers that are able to support the Service Requestservice request. The MSO may then interrogate the Controller controller to validate its continued available capacity. The MSO and the Controllers controllers report reference information back to A&AI AAI upon completion of a Service service request to be used in subsequent operations.8.1
Application, Network, and
Infrastructure ControllerInfrastructure Orchestration
As As previously stated, orchestration is performed throughout the D2 Architecture by various components, primarily the MSO and the Application , and Network and Infrastructure controllersControllers. Each Each will perform orchestration for:
- Service Delivery delivery or Changes changes to an existing Serviceservice
- Service Scalingscaling, Optimizationoptimization, or Migrationmigration
- Controller Instantiationinstantiation
- Capacity Management
- management
For infrastructure orchestration, ONAP interfaces with the cloud provider's infrastructure control interface. Regardless of the focus of the orchestration, all recipes will include the need workflows must include steps to update A&AI AAI with configuration information, identifiers and IP Addresses.
Infrastructure Controller Orchestration
Like the MSO, Controllers will obtain their orchestration process and payload (templates/ models) from Service Design & Creation (ASDC). For Service instantiation, the MSO maintains overall end-to-end responsibility for ensuring that a request is completed. As part of that responsibility, the MSO
will select the appropriate controllers (Infrastructure, Network, and Application) to carry out the request. Because a Service Request is often comprised of one or more Resources, the MSO will request the appropriate Controllers to obtain the recipe for the instantiation of a Resource within the scope of the requested Controller. After service placement is determined, the MSO may request the creation of a Virtual Machine (VM) at one or more locations depending on the breadth of the service being instantiated and whether an existing instance of the requested service can be used. If new VM resources are required, the MSO will place the request to the Infrastructure Controller for the specific AIC location. Upon receipt of the request, the Infrastructure Controller may obtain its Resource Recipe from ASDC. The Infrastructure Controller will then begin orchestrating the request. For Infrastructure Controllers, this typically involves execution of OpenStack requests for the creation of virtual machines and for the loading of the Virtual Function (VF) software into the new VM container. The Resource recipe will define VM sizing, including compute, storage and memory. If the Resource Level Recipe requires multiple VMs, the MSO will repeat the process, requesting each Infrastructure Controller to spin up one or more VMs and load the appropriate VFs, again driven by the Resource Recipe of the Infrastructure Controller. When the Infrastructure Controller completes the request, it will pass the virtual resource identifier and access (IP) information back to the MSO to provide to the Network and Application controllers. Along the entire process, the MSO may write identifier information to A&AI for inventory tracking.
Network Controller Orchestration
NetworkNetwork Controller Orchestration
Network Controllers are constructed and operate in much the same manner as Application and Infrastructure Controllers. New Service service requests will be associated with an overall recipe procedure for instantiation of that Serviceservice. The MSO will obtain obtains compatible Network Controller information from A&AI AAI and will in turn request requests LAN or WAN connectivity and configuration to be performedestablished and configured. This may be done by requesting the Network Controller to obtain its resource recipe procedure from ASDCSDC. It is the responsibility of the MSO to request (virtual) network connectivity between the components and to ensure that the selected Network Controller successfully completes the Network network configuration workflow. A Service service may have LAN, WAN and Access access requirements, each ofwhich will of which must be included in the recipe procedure and configured to meet the instance specific customer or service requirements at each level. Physical Access access might need to be provisioned in the legacy provisioning systems prior to requesting the MSO to instantiate the service.
Application
ControlController Orchestration
Application Controllers will also be requested by the MSO MSO sends requests to Application Controllers to obtain the Application Specific application-specific component of the Service Recipe service procedure from ASDC SDC and execute the orchestration workflow. The MSO continues to be responsible for ensuring MSO ensures that the Application Controller successfully completes its Resource resource configuration as defined by the recipeprocedure. As As with Infrastructure and Network Controllers, all workflows, whether focused on Instantiation, configuration or scaling, will be obtained or originate from ASDCSDC. In addition, workflows also will report their actions to A&AI AAI as well as to MSO.
Note that not all changes in network or service behavior are the result of orchestration. For example, application Virtual Functions can change network behavior by changing rules or policies associated with Controller activities. These policy changes can dynamically Policies and rules (in the Policy subsystem) inform the controller such that the Controller can enable service behavior changes.