SDNC R11 Kohn Architecture Review

Project Overview

SDNC is a network controller based on CCSDK, which provides most of the base functionality used to implement the network controller. The SDNC project assembles those components, adding real-time configurable service logic (aka directed graphs) to implement network controller instances or "personas".

New component capabilities for Kohn, i.e. the functional enhancements.

The following table lists the new functional requirements CCSDK/SDNC is committing to support for the Jakarta Release:

Minimum Viable Product

The following epics represent the minimum viable product of the CCSDK/SDNC Jakarta Release:

The following epics are also in scope for Jakarta, but are not considered of the minimum viable product.  In the event of unanticipated resource constraints, these could be reduced in scope or deferred without impacting any functionality deemed by the TSC as critical for Istanbul.

These requirements require enhancements to existing CCSDK/SDNC functionality, as opposed to new interfaces. 

New or modified interfaces

The SDNC northbound interfaces are based on the RESTCONF standard.  Currently, OpenDaylight - and therefore SDNC - support 2 versions of the RESTCONF standard:

• The Bierman-02 internet draft (see https://tools.ietf.org/html/draft-bierman-netconf-restconf-02)
• The formal, approved RFC - RFC 8040 (see https://datatracker.ietf.org/doc/html/rfc8040)

OpenDaylight has announced that support for the Biermann-02 draft is deprecated in their OpenDaylight Sulfur release and will be removed in the following release (Chlorine).

RFC 8040 is NOT backwards compatible with Biermann.  SDNC plans to announce that the Bierman internet draft support is deprecated in Kohn and to advise clients to move to RFC 8040.  However, we anticipate that not all clients will be able to move to RFC 8040 in a timely manner.  Therefore, we are planning to develop our own support for Bierman in London release.  The details of our migration strategy are described in RESTCONF migration strategy

If they are modified, are they backwards compatible?

Yes.  Care is taken to ensure backwards compatibility:

• Any new fields added are declared as optional, with reasonable defaults assigned, so that version N of CCSDK/SDNC can be used with version N-1 of its interface peers.

Interface naming (point to an example)

CCSDK provides the following APIs which are exposed by SDNC:

• A1-ADAPTOR-API : RESTCONF interface which implements O-RAN's A1 interface
• ASDC-API : RESTCONF interface used to process certain non-TOSCA artifacts distributed by SDC (license model updates).
• dataChange : RESTCONF interface pub/sub interface that allows controller to be notified on data change events (note: not currently used in ONAP use cases)
• LCM : RESTCONF interface used to handle LifeCycle Management events
• SLI-API : RESTCONF interface to service logic interpreter.  Used primarily for health check.
• selfservice-api : gRPC interface used with CDS
• oofpcipoc-api : RESTCONF interface used for OOF/PCI integration

SDNC itself also provides the following interfaces, not found in CCSDK:

• GENERIC-RESOURCE-API : supports assignment of network resources, via automation and preloaded data]

Reference to the interfaces.

All APIs have Swagger documentation, which is referenced in readthedocs

What are the system limits?

Due to limitations inherent in OpenDaylight clustering - which is based on akka - SDNC should always be run with an odd number of replicas. This is needed to guarantee there can be no "ties" in the akka leader election procedure.

Involved use cases, architectural capabilities or functional requirements.

SDNC is used in the following use cases:

• vFW
• vDNS
• vCPE
• VoLTE
• CCVPN
• 5G
• BBS

Listing of new or impacted models used by the project (for information only).

None