Convergence Switching and the Next-Generation Carrier

Provisioning of the dacs toll and access tandem

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Unformatted text preview: fairly static, voice-oriented environment. Provisioning of the DACS, toll and access tandem switches, and trunks is cumbersome but acceptable, as a result of fairly consistent voice traffic patterns. During the late 1980s and early 1990s, however, the rapid growth of distributed processing and the Internet changed everything. Dial Internet access devoured PSTN circuits with unexpected call duration times and resulted in diminished quality of service (QoS), as voice users experienced “fast busies.” The avalanche of Internet users forced carriers to invest in additional PSTN capacity, a costly exercise—given that large circuit switches cost between $1 and $3 million and DACSs between $100,000 and $250,000 for traffic that was providing little if any incremental revenue. In addition, the bursty characteristics and bandwidth demands (DS–1 to DS–3) of data transmission were not well suited to the circuit-switched nature of the PSTN and required few of its value-added voice features. Packet-switched networks could accommodate the rapid growth and handle the bursty characteristics of data applications more efficiently than the PSTN’s fixed 64– kbps architecture. Carriers quickly concentrated their efforts on data-centric architectures and constructed or expanded frame relay, ATM, and IP networks, most of which rely on ATM as the core technology, in the underlying backbone of the network. The specialization of voice and data or packet networks has resulted in carriers supporting a large number of overlay networks (see Figure 1). Figure 1. PSTN Architecture Web ProForum Tutorials Copyright © The International Engineering Consortium 3/14 British Telecommunications PLC, for example, has no fewer than 17 overlay networks, each of which requires separate network management and back-office systems and support, and each of which has varied technical standards and protocols. The explosive growth of data traffic also forced carriers to expand their data network infrastructures constantly. The growth has been so rapid that companies such as MCIWorldCom experience annual data backbone growth rates of roughly 800 percent, while vo...
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This note was uploaded on 10/15/2011 for the course ECON 1102 taught by Professor Jahis during the Spring '09 term at University of Minnesota Crookston.

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