 adjusted to allow that. Besides the proposed model in RFC 8575, some equipment vendors are also designing and imple- menting their own proprietary YANG models that describe both configuration and performance as- pects of PTP clocks. The YANG model for Cisco XR-based PTP clocks is one such example. Figure 12-23 illustrates a simplified mechanism of using NETCONF and YANG to manage PTP clocks from a central management node. Note that the figure illustrates a theoretical model, which, at the time of writing, is possible only by using proprietary YANG models and when all the devices in the topology support NETCONF and YANG. Automation and assurance station PTP YANG model (Config & Oper) Performance & anomalies Configurations NETCONF client NETCONF NETCONF NETCONF server server server Device Device Device software software software model model model Figure 12-23 Management of PTP Clocks Using NETCONF and YANG To configure and provide full performance monitoring, these proprietary YANG models go beyond the standardized model that has been proposed. The Cisco proprietary YANG models for Cisco XR-based PTP clocks is one such example. Their implementation of this YANG model has two main categories and multiple subcategories: YANG models for configuration: Different subcategories under this include generic configura- tion and equipment-specific configurations. For example, Cisco has Cisco-IOS-XR-ptp- cfg.yang and Cisco-IOS-XR-ptp-pd-cfg.yang. YANG models for monitoring of operational parameters: Cisco-IOS-XR-ptp-oper.yang, Cisco-IOS-XR-ptp-pd-oper.yang, and Cisco-IOS-XR-ptp-pd-oper-sub1.yang are models that capture the data elements needed to give an operational view of the status of the PTP clocks. These YANG models can be inherited and can be used by network management solutions (using either NETCONF or some other protocol) for configuring and managing PTP clocks in the network. At the time of writing, there are very few solutions that exist to manage SyncE and PTP clocks ex- clusively via NETCONF/YANG, at least for the