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CCVPN Topology discovery aims at enabling physical network resources onboarding in ONAP. Topology discovery is performed for all the 3rd party SOTN controller's which are added to ONAP thereby enabling multi domain support.

Topology discovery is based on IETF's based ACTN models (draft-ietf-teas-yang-te-topo) using RESTCONF protocol (RFC 8040) aims at discovering the abstract topology information.

Topology Discovery Flow

1. Register the 3rd party SOTN Controller to ESR.
2. ESR trigger a 3rd Controller registered event to Dmaap.
3. SDNC subscribe the event and this event notified .
4. SDNC synchronize the topology from 3rd SOTN controller.
5. SDNC analyse the data from 3rd SDN controller.  Get the nodes, links, terminal points of the topology.
6. SDNC call A&AI to create the nodes, links terminal points to save the topology.
      Note: For multi 3rd SDN controllers, there will be several topologies notified.  The links across the domain topology should be discovered or created by ONAP. 

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