PDF of this tutorialNetwork service providers in today's deregulated telecommunications market have a tremendous opportunity to build competitive advantage into their network architectures. Market factors and technological advances are joining forces to enable service providers to offer unsurpassed service and feature capabilities and dramatically reduce the cost and complexity of building and operating their networks.
Emerging network technologies will soon render today's complex mix of network elements obsolete and will help network operators run simpler and more flexible networks. The array of equipment required to string together time-division multiplex (TDM), asynchronous transfer mode (ATM), and frame-based packet-switching functions has become increasingly complicated and inefficient. Network service providers must run separate operations for multiple network overlays. This requires expertise in multiple technologies with equipment from multiple vendors to manage each transport-network type. In addition to the expense of supporting this infrastructure, the length of time required to provision services from such a platform reduces network-operator competitiveness.
The new paradigm for building or expanding the network infrastructure, on the other hand, converges the functions of time-division backbone switches into fewer network elements. The result is an infrastructure that is simpler, less expensive to manage, and capable of delivering more sophisticated and flexible functions. These newer architectures remove barriers to operational efficiency and flexible provisioning by creating a unified network that can be operated and managed cohesively.
Converged architectures combine the functions of multiple layers of the open systems interconnection (OSI) network model into fewer pieces of equipment. This dramatically simplifies network topology and reduces capital investments and the cost of operations. In addition, this design significantly enriches service features because of the intelligent capabilities within the consolidated device.
Convergence is already occurring in the transport segment of many public network backbones through the integration of TDM–based, 3/3 digital cross-connect systems (DCSs) with ATM switches. Thus, the ATM switches provide both ATM switching and the 3/3 DCS function of grooming multiple, partially filled, distributed single-layer test method 3 (DS–3) links by aggregating traffic from them onto fewer, more fully utilized DS–3 circuits.
Many network cores have migrated from circuit-switched TDM platforms to packet-switched ATM infrastructures. ATM is run over synchronous optical network (SONET) or newer wave-division multiplexing (WDM) and dense wave-division multiplexing (DWDM) Layer-1 infrastructures.
After its success in the backbone, ATM switches or DCS convergence is now being extended to the access network, where the functions of legacy 3/1/0 DCSs are being integrated into a new generation of multilayer, multiservice access switches. Again, this consolidation will yield huge savings in equipment and operations costs. In addition, service providers will achieve more efficient utilization of access bandwidth, while building a network with unprecedented flexibility, simplicity, scalability, and manageability.
