Architecture

The OB-BAA software architecture is based on the logical system architecture where standardized northbound interfaces are defined for management (M_{inf_xxx}) and control (M_{fc_xxx}). The standardized management interface is further broken down in the BAA layer administration (M_{inf_net-map}, M_{inf_eq-inv}) and the device management interfaces (M_{inf_Lxxx}). The representation of the AN is exposed through each of the interfaces using access control to restrict access to parts of the AN.

While most northbound interfaces used by OB-BAA are standardized, several interfaces (e.g., M_{fc_L2-3}) are used that haven’t been standardized or are in the process of standardization.

ANs interact with the BAA layer through the adapters of the SBI. These adapters can be specific a vendor's implementation or can be generic in the sense that vendors that have the same SBI can share a default adapter for the type of device.

High-level Software Architecture Components

A high-level software architecture is depicted below that implements the logical system architecture described in the previous section.

The roles and responsibilities of each of these components are as follows.

Southbound Adaptation Interface (SAI) & Southbound Interface (SBI)

This layer addresses the functional requirements documented under Section 7.2 & 7.3 in OB-BAA system description by providing a java based interface to the BAA Core.

The SAI and SBI hosts the interfacing/adaptation modules that allow for communication between the BAA layer and managed devices connected through the SBI including the protocol specifics required for device communication between the BAA layer and the managed device.

Broadly the SAI and SBI host two components:

1. SBI Connectors

2. Supporting Protocol Stacks

SBI Connectors

SBI Connectors act as the boundary object for interactions of other layers with SAI & SBI layer. SBI Connectors implements a java interface that exposed to the BAA Core. The BAA Core uses this interface to communicate with the device.

This interface allows the BAA Core to:

• Execute requests on the device (e.g., NETCONF edit-config)

• Receive notifications via callbacks from the device (e.g., NETCONF notification)

SBI connectors uses the Device Admin store for retrieving device connectivity details and also regularly updates the connectivity status. An instance of SBI Connector is required for each supported protocol for communication with Device.

The NETCONF Connection Manager is responsible for establishing, maintaining and tearing down NETCONF sessions with the managed devices. It also maintains the connection state of the device.

NETCONF Stack

The NETCONF Stack component implements the NETCONF Client and provides APIs to the NETCONF Connection Manager for interactions with managed devices.

SNMP Stack

The SNMP stack component implements the SNMP client and provides API to device adapters for interactions with managed device.

vOLTMF - vOLT Management Function

The vOLT Management Function (vOLTMF) is responsible for:

• Receiving notifications from the OLT regarding the detection state of the ONU.

• Notifying the vOMCI function whenever an ONU is detected or undetected.

• Receiving management and control requests from the Access SDN M&C.

• After detecting on-line ONUs, generating and sending requests for OLT configuration via the interface with OLT, and ONU requests that use the OLT’s OMCI channel via the interface with the vOMCI proxy.

• Receiving connectivity information between the OLT and vOMCI function and proxy from the Access SDN M&C and sending the connectivity information to the vOMCI function and/or vOMCI proxy.

• Receiving notifications including events and alarms from the OLT, vOMCI proxy and vOMCI function and sending notifications to the Access SDN M&C.

For more information about the vOLT Management Function

ONU Authenticator - ONU Authentication Function

The ability for the operator to identify an ONU and authenticate that the ONU belongs to a subscriber of one or more services from the operator has been traditionally performed as an function embedded within the physical OLT. In this regard the OLT acted as the policy enforcement point (PEP) and policy decision point (PDP). The ONU Authentication function allows the BAA layer to act as a PDP entity where the BAA layer itself is able to perform the identification and authentication of an ONU based on a set of policy rules or it can work in concert with the OLT and/or other SDN management entities to collectively identify and authenticate the ONU.

Several scenarios are supported by the BAA layer:

• vOMCI (Separated model) and ONU authentication in the BAA layer
• vOMCI (Separated model) and ONU authentication in the OLT (for PLOAM credentials) and the BAA layer (for LOID & OMCI Mutual Authentication protocol)
• eOMCI (Combined model) and ONU authentication in the OLT (BAA layer not to be engaged ! )

For more information about the ONU Authentication Function

NAI & BAA Core

BAA-Core addresses the functional requirements identified under Section 7.1 & 7.4 in the OB-BAA system description. These components are responsible for implementing the functionality needed by the various BAA deployment modes (i.e., BAA Actuator, UAM)

Primary blocks in this component include the following:

1. Aggregator

2. Network Topology and Equipment Inventory (NTEI)

Aggregator

The Aggregator component is the interface point between the BAA Core and NBI Adapters. The interface is implemented using a java interface that is exposed over NAI layer.

The Aggregator implements the requirements defined in Section 7.4 of OB-BAA system description.

The functionality provided by the Aggregator component includes the ability to:

• Redirect requests coming from NBI to appropriate management component with-in the BAA Core

• Forward notifications and events coming from lower layers to one or more SDN Managers and Controllers connected via the NBI Adapter. In particular, more information on Alarm filtering is available here

For more information on the Aggregator Component

Network Topology and Equipment Inventory (NTEI)

The NTEI component is responsible for maintaining the Access Network Map (ANM) for managed devices and implementing the device administration & management functions necessary to operate the BAA layer.

In addition the NTEI components provides the persistent management agent (PMA) functionality that acts as the system's source of truth for the managed devices even when the devices are not currently connected to the network.

Device Manager

The Device Manager component controls the lifecycle and administration of managed devices. The component is responsible for the instantiation and maintenance of managed device within the BAA layer including any information necessary to establish and maintain communication with the managed device. OB-BAA has defined a YANG module that includes necessary information required for the discovery of the managed device and to maintain connectivity with the device.

The Aggregator component directs device administration requests from the NBI towards the Device Manager component where the Device Manager persists the information in the Device Admin Store.

PMA Registry

PMA Registry component represents managed devices as physical Access Node (pAN) instances using the BAA layer's data models defined for that type of device.

Following are the major functions of the PMA Registry:

• Maintain Device Config Store for incoming requests

• Provide offline and online persistency for managed devices. If a device goes offline, when the device connects back the pending instructions will be played back into the device.

• Maintains a mapping table with Device Adapter used by the managed device

• Interacts with SBI Connectors

Upon receiving a request for a managed device, the PMA Registry component retrieves details about the managed device from the Device Admin store and looks up the corresponding Device Adapter. The PMA Registry component then sends the request to the Device Adapter for processing.

On receiving notifications and events from the SBI Connector component, the PMA Registry component passes them to the right Device Adapter for further normalization to pAN YANG data model. The PMA Registry component then propagates the normalized notification or event to layers above it. When deployed as a BAA Actuator, the notification and events will be passed to the Aggregator component.

Further information on how Alarm notifications are reported is available here.

Interaction with SBI Connectors

For each managed device, the PMA Registry component maintains a SBI Connector reference for the Device Adapter that is used by the managed device and subscribes to Connection Manager's call back interface for receiving notifications and events from devices.

Device Adapter

The Device Adapter component performs translation of device specific data models into the data models identified to the BAA layer's SAI component.

• The Device Adapter component receives requests from PMA registry which it translates to device specific request and uses supported protocol specific Connection Manager to deploy the instruction into the managed device.

• The Device Adapter component also normalizes the device specific notifications and events to the data model supported by the BAA layer's SAI component for that type of device and then forwards the notification and event to the PAM Registry component.

For more information on the Device Adapter

NBI Adapter

The NBI Adapter component addresses the functional requirements documented under Section 7.5 in OB-BAA System description which adapts the YANG data model exposed by the NAI into a protocol specific interface (e.g. NETCONF) which interacts with SDN Manager and Controllers as well as the BAA Core.

NBI Adapter component uses the NAI java interface exposed by Aggregator component to:

• Relay requests originating from the North

• Registers to callback for notification and events from the Aggregator component; forwarding them to the respective SDN Manager and Controllers

Infrastructure

Infrastructure component contains the supporting utilities needed by the BAA layer. These include:

Logging

Utility used by components to create & maintain logs.

User Management

Functions for create & administer users.

NETCONF Server Framework

Provides tools for NETCONF Client & Server implementation. This includes utilities like YANG module handling, security etc.

Debugging

Provides debugging utilities for application troubleshooting.

BAA Services

The BAA layer has several services that provide needed functionality to manage and control Access Nodes (AN). In this release the following services are provided:

• PM Service

• Data Lake

• vOMCI Function

• vOMCI Proxy

• Control Relay Service

PM Service

OB-BAA supports IPFIX (RFC 7011) based PM Collection from AN. PM data collection function in BAA is realized as a dedicated micro-service.

It has two architectural components:

• PM Collector module

• DataHandler module

PM Collector

The PM Collector is responsible for collecting performance monitoring data (IPFIX messages) from managed pANs, The PM Collector will decode and provide formatted data to data handlers for further processing and storage of data. The IPFIX PM Data Collector (IPFIX Collector) is based on IETF's RFC 7011 IPFIX protocol specification and mechanisms as IPFIX is the method defined by the BBF's TR-383 specification.

IPFIX collector decodes IPFIX messages into the requisite Information Elements (IE) and their associated values. This is then forwarded to Data Handler(s) (IpfixDataHandler) that subscribes to IPFIX Collector.

For more information on the PM Collector

PM DataHandler(s)

PM DataHandlers are karaf modules plugged into the PM micro-service and subscribes to the PM Collector for the counter stream. Several PM DataHandlers can be implemented depending on the post processing needs. The OB-BAA reference implementation comes with two reference Data Handlers.

Persistence Manager Data Handler

Persistence Manager is a reference PM Datahandler which subscribes to IPFIX collection stream and updates them into a common data lake. OB-BAA uses InfluxDB as its common data lake. The Persistence Manager does reformatting of the incoming counter stream into tags & counters before updating them into the persistence store. Once in the persistence store, counter information can be queried from the data store by management and control elements using the interface provided by InfluxDB.

Logger Data Handler

The Logger is another reference PM DataHandler which subscribes to IPFIX collection stream and logs it into the BAA application log.

Data Lake

OB-BAA bundles InfluxDB as its common data lake for storing PM Counters. InfluxDB is a time series database, hence ideal for maintaining PM counters which is tracked based on time. InfluxDB provides a HTTP based API interface for querying data which can be used by SDN M&C and other management entities. It also provides a graphical user interface for data visualization purpose.

vOMCI Function

The vOMCI function is responsible for:

• Receiving service configurations from the vOLT Management function

• Translating the received configurations into ITU G.988 OMCI management entities (ME) and formatting them into OMCI messages

• Encapsulating and sending above formatted OMCI messages through the OLT to the attached ONU

• Translating the received ONU's operational data from the OLT and sending it to the vOLT Management function

For more information on the vOMCI Function

vOMCI Proxy

The vOMCI Proxy works as an aggregation and interception point that avoids the need for an OLT to directly connect to individual vOMCI Functions and can act as a control/interception point between the OLT and vOMCI function that is useful for troubleshooting and other management purposes (e.g., security). As the aggregration/interception point, the vOMCI Proxy is responsible for maintaining the associations between OLTs and the corresponding vOMCI functions.

For more information on the vOMCI Proxy

Control Relay Service

The Control Relay Service along with the AN Control and Control Protocol Adapters provides the capability to relay packets from an AN to an application endpoint in the SDN Management and Control functional layer.

The determination of which packets are relayed between the access node and SDN M&C application endpoint is configurable through the M_fc-conf reference point.

For more information on the Control Relay Service

Service Discovery

The Service discovery is used to retrieve VNF details from Container management tool. In this release Kubernetes is the supported container orchestrator. This service allows OBBAA user to query the list of VNFs, their status & details. The Module uses the orchestrator API (for Kubernetes its REST API) to retrieve the requested details.

For more information on Discovering micro-services

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