dentifier based implementation in SNMP, the document based approach in NETCONF makes it much easier to manage network devices. Data exchange based on APIs: NETCONF allows devices to expose API that can be used for exchanging configuration data. Inherently XML based: - NETCONF is an XML-based protocol, SO all the advantages of using XML for structured data exchange is applicable to NETCONF. Secure connection: NETCONF uses a secure and connection oriented ses- sion for communication between agent and server. Ease of adding new features: The functionality of NETCONF can closely mirror the device functionality. This results in quick adoption of new features at much lower implementation costs. Multiple database support: The NETCONF system can query one or more databases for network management data. Most industry leaders in operation support space have embraced XML-based pro- tocols. NETCONF is one of the most popular XML-based protocols and hence has been used in this chapter to discuss management operations. 32.2 NETCONF NetConf, short for network configuration, is based on the client-server model and uses a remote procedure called (RPC) paradigm to facilitate communication. The messages are encoded in XML and are sent over a secure, connection-oriented ses- sion. The contents of both the request and the response messages are described using XML. The client is a script or application typically running as part of a net- work manager and the server is the agent in the network device. The layers in NETCONF are (see Figure 32.1): 1. Content layer: This is the topmost layer and corresponds to configuration data being handled using NETCONF. 2. Operation layer: Has a set of methods for communication between agent and manager. Application Layer Content Operations Transport Figure 32.1 Layers in NETCONF. 3. RPC layer: Used for encoding the remote procedure call. 4. Transport layer: This layer corresponds to the transport path for communica- tion between the server and client. NETCONF supports transport over SSH, SSL, BEEP, an