SERVICE ABSTRACTION (e.g., VPN with 2 sites, Internet Access, QoS) NETWORK YANG MODELS COMMON NETWORK ABSTRACTION What needs to be built in the network? (e.g., L2-VPN, QoS, BGP) DEVICE MODEL DEVICE YANG MODELS What Vendor-specific configuration is needed? Network Elements FIGURE 10.13 Abstraction layers for data modeling. model also drives the agreement on vocabulary and jargon. In addition, a data model can automate some tasks-design tools can take a model as an input and generate the initial database structure and device configuration. Data models could serve as an important tool to estimate the potential complexity asso- ciated with a network design project. This estimation could eventually be useful to gain insight into the level of development effort and project risk. Enhancements to services as a result of new business requirements can assess the impact to the existing network design by identifying the scope very clearly. In addition, reuse of the data models enables network designers to shorten their development cycle considerably. Deployment and replacement of specific network devices becomes easy; this in turn reduces the time to market or time for resolution of issues. Today, the industry has more or less standardized on using YANG as a data modeling language for networking environments. The use of this modeling language has significantly improved the process of network design. Use of the new process has allowed us to improve both cost and time associated with service development while reducing the typical errors seen in prior processes. Just like an architect creates a blueprint before constructing an actual building, the network designers can now create YANG-based blueprints before worrying about the choice of vendor device, capa- bility of each device, etc. Once the service models and device model blueprints are ready, software tools are used to generate device-specific CLIs thus restricting human intervention only to the ser- vice design stage. 10.4.3 VF DEPLOYMENT AND MANAGEMENT As mentioned in Cha