provisioned separate networks for voice, video, and data applications. In most cases, enterprises deployed voice, video, and data networks autonomously and operated them in isolation. Enterprises managed and implemented these networks with separate teams. The separate networks encompass the enterprise local and wide-area networks. In simple terms, voice traffic used PBXs and data used routers. PBXs connected to dedicated leased lines. Data used a combination of leased lines, Frame Relay, and ATM. Figure depicts a typical deployment of these disparate networks. Video relied on special and very expensive leased line connections. This use of disparate facilities for each application transport is extremely inefficient. The volume of data traffic is growing faster than the volume of voice traffic, driven by emerging and evolving technological innovations such as the World Wide Web (WWW), e-commerce, and applications such as videoconferencing or video streaming using IP multicast. While growth rates vary by country and carrier, it is certain that data transport will soon dominate telephony networks. Data has already surpassed voice on some U.S. service provider networks. Data is the driving force behind global network growth. The challenge for the enterprise is to optimize networking to carry data, voice, and, most recently, video traffic. It is widely accepted and acknowledged by the communications industry and industry analysts as a whole that IP will become the universal transport of the future. The rapid adoption and migration of vendors to the use of IP as a transport for data, voice, and video applications further endorses the transition to a converged networking paradigm. The vendors changing to IP includes those vendors who have historically used time-division multiplexing (TDM) infrastructures and relied on old practices. Figure shows an enterprise network converging over common IP transport. Using IP as the form of transport offers the enterprise significant statistical gains in bandwidth efficiency, lower overall bandwidth requirements, ease of management, and the ability to deploy new applications rapidly. There are fewer WAN facilities and fewer devices required to terminate those facilities. Enterprises add bandwidth incrementally as required and statistically share bandwidth between applications, adding efficiency and reducing complexity. Convergence provides an economic inducement to companies as well. When companies subscribe to disparate network models, they often pay for services even though they are not being used. In a converged environment, bandwidth is shared amongst voice, video, and data applications. For example, when voice is inactive, data can use the available bandwidth; when voice or video applications are active, required bandwidth for these operations is guaranteed.
Content 1.2 Describing Converged Network Requirements 1.2.1 Hierarchical Network Model Despite current information technology (IT) investment, many organizations find that vital networked resources, applications, and information assets remain largely unlinked. In fact, it is common for organizations to have hundreds of applications and databases that cannot communicate with each other. This is due in part to increasing and often unexpected demands from internal and external customers. Many enterprises have to deploy new technologies and applications quickly. This often leads to the deployment of disparate systems. The result of these new deployments is an inability to share information efficiently across the organization. For example, sales, customer service, or purchasing departments cannot access customer records easily without creating different overlay networks that join applications and information. Many organizations have found that unplanned expansion has left them with multiple systems and distributed resources that are uncoordinated and underused. The disparate systems are also difficult and costly to manage. The Cisco Intelligent Information Network (IIN) helps IT organizations to solve these problems and meet new challenges including service-oriented architectures, web services, and virtualization using network architectures. IIN articulates the evolving role of the network in facilitating the hardware and software integration that makes it possible for organizations to better align IT resources with business priorities. By building intelligence into an existing network infrastructure, IIN helps organizations realize benefits such as reduced infrastructure complexity and cost. The Cisco Service-Oriented Network Architecture (SONA) provides a pathway to achieving the IIN vision. To understand the situation, this lesson reviews the traditional network design model that many of today’s enterprises used to build their networks. The traditional model uses a three-layer hierarchical model. Initially, the model provided a modular framework that allowed flexibility and made implementation and troubleshooting easy. The hierarchical model divides networks or their modular blocks into the access, distribution, and core layers. Each layer has specific features: Network designers can apply the hierarchical model to any network type including LANs, WANs, wireless LANs (WLANs), metropolitan-area networks (MANs), and virtual private networks (VPNs) and to any modular block of the Cisco networking model. Figure presents an enterprise network using the traditional hierarchical model design.
Content 1.2 Describing Converged Network Requirements 1.2.2 Cisco Enterprise Architectures Cisco provides the enterprise-wide systems architecture that helps companies to protect, optimize, and grow the infrastructure that supports business processes. The architecture provides for integration of the entire network—campus, data center, WAN, branches, and teleworkers—offering staff secure access to tools, processes, and services . From an Information Technology staff point of view, the Cisco Enterprise Architecture facilitates planning, designing, implementing, operating, and troubleshooting (PDIOT) networks by focusing on network elements and on the relationships between those elements.The Cisco Enterprise Architectures consist of five elements: