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O-RAN Specification Compliant O2 Interfaces

Storyboard: https://storyboard.openstack.org/#!/story/2010278

To facilitate the integration of components in context of O-RAN architecture, O-RAN Alliance publishes a set of specifications to normalize the interfaces between them, as far as O-Cloud concerned, the O2 interfaces are specified between O-Cloud and O-RAN SMO. As part of effort to make StarlingX be compliant to O-RAN specifications, oran O2 service is developed and integrated into StarlingX (either standalone mode or distributed cloud mode) to expose O2 interfaces towards to SMO.

Problem description

Users want to integrate StarlingX as O-Cloud to O-RAN SMO via O2 interfaces published by O-RAN Specifications as below:

WG6: O-RAN O2ims Interface Specification v3.00 <https://oranalliance.atlassian .net/wiki/spaces/TSC/pages/2570617688/APPROVED+-+WG6+O-RAN+O2ims+Interface+ Specification+v3.00>

WG6: O-RAN O2dms Interface Specification: Kubernetes Native API Profile for Containerized NFs v2.00 <https://oranalliance.atlassian.net/wiki/spaces/TSC/ pages/2570715602/APRROVED+-+WG6+O-RAN+O2dms+Interface+Specification+Kubernetes+ Native+API+Profile+for+Containerized+NFs+v2.00>

Hence it is expected that following O2 services are deployed over StarlingX:

  • O2ims_InfrastructureInventory
  • O2ims_InfrastructureMonitoring
  • O2dms in Kubernetes native API profile

Use Cases

This feature addresses several use cases specified by: WG6: O-RAN Cloudification and Orchestration Use Cases and Requirements for O-RAN Virtualized RAN v5.00 <https://oranalliance.atlassian.net/wiki/spaces/ TSC/pages/2569831376/APPROVED+-+WG6+O-RAN+Cloudification+and+Orchestration+ Use+Cases+and+Requirements+for+O-RAN+Virtualized+RAN+v5.00>

Specifically, the following Use cases and Requirements should be realized:

  • O-Cloud Registration and Initialization Use Case
  • O-Cloud Inventory Update Use Case
  • Network Function Basic Use Cases
  • Fault Use Cases

The use cases above should be applicable to StarlingX in either standalone mode or distributed cloud mode.

Proposed change

An oran-o2 service <https://docs.o-ran-sc.org/projects/o-ran-sc-pti-o2/ en/latest/index.html> has been developed as part of INF project of o-ran software community.

This oran-o2 service has been designed and implemented to host the o2ims services including O2ims_InfrastructureInventory, O2ims_InfrastructureMonitoring, and other O2 services in future to represent StarlingX as an O-RAN Specifications compliant O-Cloud.

This oran-o2 service will be packaged as a new FluxCD based containerized application. Users decide whether to deploy this oran-o2 service and when. In case of StarlingX in distributed cloud mode, oran-o2 will be deployed over system controller only.

Fundamentally, the oran-o2 services act as a mapping layer to map between StarlingX resources and corresponding service objects of O-RAN specifications.

Specifically, the following O-RAN service objects are mapped to StarlingX resources:

O-RAN model

StarlingX in standalone mode

StarlingX in distributed cloud mode
================= ================================ ===========================

O-Cloud

a StarlingX instance

a System Controller and all subclouds it manages

ResourceType

StarlingX sysinv API resource kind

StarlingX sysinv API resource kind, refer /o2ims -infrastructureInventory/v1 /resourceTypes for examples

ResourcePool

a StarlingX instance

a instance of subcloud, refer to /o2ims-infrastructureInventory/v1 /resourcePools for examples

Resource

Specific instance of StarlingX sysinv API resource

Specific instance of sysinv API resource, refer to /o2ims-infrastructureInventory/v1 /resourcePools/ {resourcePoolID}/resources for examples

DeploymentManager

a single Kubernetes cluster hosted by a StarlingX instance

a single Kubernetes cluster hosted by a subcloud, refer to /o2ims-infrastructureInventory/v1 /deploymentManagers for examples

AlarmDefinition

Fault Management Alarm Message definition

Fault Management Alarm Message definition

AlarmEventRecord

an occurrence of Fault Management Alarm Message

an occurrence of Fault Management Alarm Message

AlarmSeverity

Fault Management Alarm Severity

Fault Management Alarm Severity

As implementation of o2ims services, the oran o2 service monitors sysinv resources via sysinv api, builds a cache of resources compliant to O-RAN O2 model as inventory and persists them into internal database.

On the other hand, oran o2 service exposes this inventory to SMO through a set of O2 APIs for querying resources as well as subscribing to get notification upon the inventory changes and alarm changes.

As implementation of o2dms, the kubernetes clsuters hosted by StarlingX will be exposed as O2dms in kubernetes native API profile, while the access information of these clusters are exposed as deploymentmanager object as part of o2ims inventory. So SMO could query the it to extract the access crendentials, and interact directly with the specific kubernetes cluster with kubernetes native APIs.

To make oran o2 service survive through the migration of oran-o2 pods among different StarlingX hosts, the inventory database is persisted by leveraging kubernetes PV volumes.

Alternatives

It has been considered to couple the o2ims service with sysinv service to optimize the efficiency of monitoring sysinv resource changes. However, given that O-RAN specifications is still in early stage of its rapid evolution progress, it is decided to decouple these two services and integrating them by utilizing existing sysinv API for now.

Data model impact

As part of the o2ims inventory, a new group of tables will be introduced to persist O-RAN modeling compliant objects representing StarlingX sysinv resources. This inventory is internally managed as part of deployment of oran o2 service. The diagram below shows the new table names and relationships.

The resourcetype table is populated with predefined resourcetypes as below: - pserver - pserver_cpu - pserver_mem - pserver_ethernet - pserver_if

The resource table contains specific o2ims resources which represents the corresponding sysinv resource accordingly to predefined resourcetypes. The resource are organized in a hierachical way to represent the relationship between each other, e.g. an instance of pserver_cpu refers to a instance of pserver with its parentid. an instance of pserver refers to an instance of resourcepool which represents the subcloud.

The resourcepool table contains representations of each subcloud.

The deploymentmanager table contains representations of kubernetes cluster for each subcloud

The ocloud table contains a single representation of StarlingX instance in either standalone mode or distributed cloud mode.

The subscription table contains information of subscribers which are interested in receiving notification upon the changes of o2ims inventory.

The configuration table contains provisioning information, e.g., smo endpoint for o-cloud registration

The alarmSubscription table contains information of subscribers which are integrated in receiving alarm notification.

The alarmEventRecord table contains information of alarms generated by StarlingX system.

REST API impact

Following the spec of O-RAN Alliance as of this writing, WG6: O-RAN O2ims Interface Specification v3.00 <https://oranalliance.atlassian .net/wiki/spaces/TSC/pages/2570617688/APPROVED+-+WG6+O-RAN+O2ims+Interface+ Specification+v3.00>, the following APIs will be added:

o2ims-infrastructureInventory/v1

GET o2ims-infrastructureInventory/v1

RESP:

/o2ims-infrastructureInventory/v1/resourceTypes

GET /o2ims-infrastructureInventory/v1/resourceTypes

RESP:

/o2ims-infrastructureInventory/v1/resourceTypes/{resourceTypeID }

GET /o2ims-infrastructureInventory/v1/resourceTypes/ dcce9bcc-fb38-4e49-bf84-4f1519f3b031

RESP:

/o2ims-infrastructureInventory/v1/resourcePools

GET /o2ims-infrastructureInventory/v1/resourcePools

RESP:

/o2ims-infrastructureInventory/v1/resourcePools/{resourcePoolID}

GET /o2ims-infrastructureInventory/v1/resourcePools/ 42700a14-21d6-405c-a362-e691b20656b1

RESP:

/o2ims-infrastructureInventory/v1/resourcePools/{resourcePoolID}/resources

?{filters}

GET o2ims-infrastructureInventory/v1/resourcePools/ 42700a14-21d6-405c-a362-e691b20656b1/resources?resourceTypeName=pserver

RESP:

o2ims-infrastructureInventory/v1/resourcePools/{resourcePoolID}/resources/

{resourceID}

GET o2ims-infrastructureInventory/v1/resourcePools/ 42700a14-21d6-405c-a362-e691b20656b1/resources/ 67e71e16-6264-4ac0-b57f-815cf6b7dc70

RESP:

/o2ims-infrastructureInventory/v1/subscriptions

POST /o2ims-infrastructureInventory/v1/subscriptions

RESP:

GET /o2ims-infrastructureInventory/v1/subscriptions

RESP:

/o2ims-infrastructureInventory/v1/subscriptions/{subscriptionID}

GET /o2ims-infrastructureInventory/v1/subscriptions/ 7900907e-b60a-4cfd-b6a5-dae760a865f0

RESP:

DELETE /o2ims-infrastructureInventory/v1/subscriptions/ 7900907e-b60a-4cfd-b6a5-dae760a865f0

RESP: None

/o2ims-infrastructureInventory/v1/deploymentManagers

GET /o2ims-infrastructureInventory/v1/deploymentManagers

RESP:

/o2ims-infrastructureInventory/v1/deploymentManagers/{deploymentManagerID}

GET /o2ims-infrastructureInventory/v1/deploymentManagers/ 9fc43d52-b73a-366a-b08f-e89cbbf82532

RESP:

/o2ims-infrastructureMonitoring/v1/alarms

GET /o2ims-InfrastructureMonitoring/v1/alarms

RESP:

/o2ims-infrastructureMonitoring/v1/alarms/{alarmEventRecordID}

GET /o2ims-InfrastructureMonitoring/v1/alarms/ 9fc43d52-b73a-366a-b08f-e89cbbf82532

RESP:

/o2ims-infrastructureMonitoring/v1/alarmSubscriptions

POST /o2ims-infrastructureMonitoring/v1/alarmSubscriptions

RESP:

GET /o2ims-infrastructureMonitoring/v1/alarmSubscriptions

RESP:

/o2ims-infrastructureMonitoring/v1/alarmSubscriptions/{alarmSubscriptionId}

GET /o2ims-infrastructureMonitoring/v1/alarmSubscriptions/ aef43d52-b73a-366a-b08f-e89cbbf82111

RESP:

DELETE /o2ims-infrastructureMonitoring/v1/alarmSubscriptions/ aef43d52-b73a-366a-b08f-e89cbbf82111

RESP: None

Security impact

oran-o2 services exposes API endpoints towards a single SMO which should be specified during provisioning time, so it is critical to reach mutually trusts with following approach:

  • The SMO API endpoint which is provisioned to oran-o2 for O-Cloud registration should be protected by https.
  • The oran-o2 API endpoint will be protected by https, the certificate management will be manually done for now, and will be integrated with cert-manager in future.
  • An initial token will be provided to SMO during O-Cloud registration.
  • SMO should use that token to request oran-o2 service via API endpoint.
  • The token should be renewed before it is expired and dispatch to SMO by oran-o2 service
  • The token received from SMO via its API requests will be validated against authentication provider. The authentication provider is the kubernetes APIserver which hosts the oran o2 service, and can be extended in future to support other authentication providers, e.g., the openstack keystone service of StarlingX.
  • The token management will be manually done for now and will be automated in future.
  • There is no user sensitive data involved.
  • There is no need for cryptography, but need hashing for checksum of resource information.
  • There is no need for sudor or any elevated privileges.
  • The oran-o2 requires openstack admin permission to interact with sysinv APIs.
  • The oran-o2 requires a kubernetes service account with binding of a clusterRole to able to interact with kubernetes APIserver.

Other end user impact

This oran-o2 service exposes new set of APIs for SMO, but it does not affect existing python-client of other StarlingX services

Performance Impact

The oran-o2 service should be no impact on system performance for following reasons:

  • As mentioned in problem description, oran-o2 will monitor the changes of sysinv resources via sysinv API, hence there is a background task polling the sysinv resources via sysinv API periodically. The configurable polling interval is in seconds level and executed in a sequential way for querying sysinv resources. It is expected this periodic task will not impact system's performance.
  • There are no database queries to system.
  • There is no locking to access system resource exclusively.
  • The oran-o2 service is deployed as kubernetes workload hence the consumed resources are predicted by resource allocation at deployment phase.

Other deployer impact

None

Developer impact

This is a new and standalone system application, it will not impact developers working on other features.

Upgrade impact

The oran-o2 has dependencies on few sysinv API as well as the kubernetes version, it should be upgraded accordingly if these components upgrading breaks the dependencies.

The oran-o2 does not affect the system's upgrade since it is designed as a standalone system application deployed over system.

The oran-o2 is implemented in cloud native way, it supports migration between hosts by nature.

Implementation

Assignee(s)

Primary assignee:

Bin Yang

Other contributors:

Rong Zhang David Liu

Repos Impacted

starlingx/app-oran-o2

Work Items

  • Create oran-o2 application package based on ORAN-SC release deliverable
  • Create FluxCD App Package by integrating oran-o2 application to FluxCD
  • Update the docs.starlingx.io for the instructions of oran-o2 application deployment and configuration, and API reference of oran-o2 services.

Dependencies

This specification depends upon the open source upstream:

O-RAN Software Community/INF project/ORAN-O2 services implementation in G Release

Testing

Functional testing will be performed on StarlingX in AIO-SX, AIO-DX, Standard and DC configurations, which includes:

  • O2 application lifecycle management in StarlingX
  • O2 Use cases verification which demonstrates the Compliance of ORAN Spec Interfaces

Documentation Impact

This work will primarily impact deployer and developers.

The API reference documentation will be provided for integrating with ORAN SMO.

The deployment guide document will be provided for deployer of StarlingX.

StarlingX release notes describing this feature will also be provided.

References

  • WG6: O-RAN Cloudification and Orchestration Use Cases and Requirements for O-RAN Virtualized RAN v5.00 <https://oranalliance.atlassian.net/wiki/spaces/ TSC/pages/2569831376/APPROVED+-+WG6+O-RAN+Cloudification+and+Orchestration+ Use+Cases+and+Requirements+for+O-RAN+Virtualized+RAN+v5.00>
  • WG6: O-RAN O2ims Interface Specification v3.00 <https://oranalliance. atlassian.net/wiki/spaces/TSC/pages/2570617688/APPROVED+-+WG6+O-RAN+O2ims+ Interface+Specification+v3.00>
  • WG6: O-RAN O2dms Interface Specification: Kubernetes Native API Profile for Containerized NFs v2.00 <https://oranalliance.atlassian.net/wiki/spaces/TSC/ pages/2570715602/APRROVED+-+WG6+O-RAN+O2dms+Interface+Specification+ Kubernetes+Native+API+Profile+for+Containerized+NFs+v2.00>
  • O-RAN SC INF project, ORAN-O2 services implementation in G release <https:// gerrit.o-ran-sc.org/r/gitweb?p=pti/o2.git;a=tree;h=refs/heads/g-release>

Acronyms

  • 3GPP: Third Generation Partnership Project
  • 5G: Fifth-Generation Mobile Communications
  • CNF: Containerized Network Function
  • DMS: O-Cloud Deployment Management Services
  • SMO: Service Management and Orchestration
  • FOCOM: Federated O-Cloud Orchestration & Management
  • IM: Information Model
  • IMS: O-Cloud Infrastructure Management Services
  • LCM: Life Cycle Management
  • NF: Network Function
  • NFO: Network Function Orchestration
  • NFVI: Network Function Virtualization Infrastructure
  • O-CU: O-RAN Central Unit as defined by O-RAN ALLIANCE
  • O-CU-CP: O-CU Control Plane
  • O-CU-UP: O-CU User Plane
  • O-DU: O-RAN Distributed Unit (uses Lower-level Split)

History

None