Orange Telefonica Telefonica Huawei Nokia This document defines a YANG data model for representing an abstract view of the provider network topology that contains the points from which its services can be attached (e.g., basic connectivity, VPN, network slices). Also, the model can be used to retrieve the points where the services are actually being delivered to customers (including peer networks). This document augments the 'ietf-network' data model by adding the concept of Service Attachment Points (SAPs). The Service Attachment Points are the network reference points to which network services, such as Layer 3 Virtual Private Network (L3VPN) or Layer 2 Virtual Private Network (L2VPN), can be attached. Both User-Network Interface (UNI) and Network-to-Network Interface (NNI) are supported in the SAP data model.