Protocols XML (Extensible Markup Language) based protocols are rapidly replacing tradi- tional management protocols like SNMP and are now the defector standard for use in web-based network management. Protocols like SOAP, which are XML-based, can be viewed in management standards like WBEM for enterprise management defined by DMTF as well as MTOSI for telecom management defined by TMF. This chapter is intended to give the reader a basic understanding of XML protocol. SOAP the most popular XML protocol and NETCONF hailed as the next genera- tion network management protocol is discussed as specific examples. 18.1 Introduction Traditionally SNMP has been the preferred protocol for network management of packet networks like Ethernet, Token-ring, and SO forth. Efficient and low band- width transport mechanisms using UDP over an IP) as well as an optimized, but limited, data model were the two main reasons for its popularity. The simplistic data model architecture used by SNMP (a flat MIB definition) was well suited for low complexity legacy packet nodes. With the convergence of traditional circuit (voice) and packet networks (data) onto a common IP-based packetized core as in next generation networks like IMS, the complexity of the network elements involved, and the services supported have undergone a huge change. With convergence in networks space, a flat and simple model like SNMP does not scale up to meeting the next generation net- work management requirements. A typical example of convergence at a network element level is an L3-L7 switch in a converged network. This switch performs multiple other functionalities in addition to switching including, but not limited Fundamentals of EMS, NMS and OSS/BSS to, authentication, encryption, and application routing. As a result, the informa- tion base to be managed is much more complex. Attempts to serve this complex information base using SNMP has resulted in a force-fitting of this information into the limited 2-dimensional SNMP MIB model. This is clearly indicated in the