t new services compared to the traditional approach (where a spe- cific service requires dedicated infrastructure with low utilization to ensure high availability), and the opportunity to automate network operations. 2.4 THE MODERN IP NETWORK The modern IP network as illustrated in Figure 2.1, is formed using high-capacity fiber optic trans- mission, optical switching and multiplexing, and packet switching technology. Each of these is combined to create local, regional, national, and international networks. In the past, virtually all telecommunications companies tended to specialize in both service type and geographic reach. With newer technologies, it has become possible to use the same network to offer a range of voice, video, data, and mobile services leading to significant competition. 2.4.1 THE OPEN SYSTEMS FOR INTERCONNECTION MODEL The primary model for networking used today is the Open Systems for Interconnection (OSI) model, which breaks network functionality down into layers (see Figure 2.2). This allows technol- ogy enhancements and change to occur without disrupting the entire stack (combination of layers). It also allows interoperation between networks (or network segments) that use dissimilar network- ing technology as long as they connect using a common interface at one of the layers. This is the method that allowed the Internet and its lower layer data networks to evolve SO quickly. Each of the different local area networks, or LANs, could evolve as long as they all connected using the com- mon Internet Protocol. 2.4.2 REGULATION AND STANDARDS No matter how organized, telecommunications networks need to be built against a set of standards in order to provide value. Internationally, the United Nations has historically had an arm called the ITU that ensured the creation of standards-based telecommunications networks. With the cre- ation of newer technologies, additional technology groups or consortia were created to facilitate the advancement of specific approaches. For the Internet, this is the Inte