 with resource-specific policy and inventory functions for assignment of resources in adherence to engineering rules. 2. The Network Resource Autonomous Control Function separates the functions and applica- tions for managing core packet and optical transport (wide area network [WAN], metro area network [MAN], and access network) resources from those managing network ser- vice resources. Core transport resources are largely "hard" resources such as router and Software-Defined Networking link bandwidths, whereas the edge service resources also need to include "soft" resources like IP addresses, VLAN IDs, etc. 6.4.1.4 Adapters Adapters interact with the network devices (e.g., network elements) and VNFs through well-defined protocols. The adapter layer contains the complexity of vendor-specific and protocol-specific imple- mentation issues for both changing the state of the network device and reading the state of the network device. A vendor may have their own proprietary controller (represented as the green box inside the device type N in Figure 6.3) or EMS, which interfaces with their network device and therefore the appropriate vendor adapter to interface with their controller or EMS would be needed. 1. Changing the state of the network is handled by "write mode" adapters. It can be done using traditional configuration through template or scripted CLI changes, transactional NETCONF with YANG changes or flow changes through protocols like Border Gateway Protocol (BGP), BGP-Flow-Spec or OpenFlow. 2. Reading the state of the network is handled by "read mode" adapters. This allows for the collection of data through protocols like SNMP, NETCONF, OpenFlow, BGP-Link-State, OSPF link state, etc. The data collected through those means are used by the controller for application processing in autonomous control loops, which would result in changes in the network state through the "write" mode adapters. The DCAE function collects the data periodically by polling or auto-streaming, or on-demand based on trigger events. 6.4.1.