N-GEN
Communications Web-based Seminars ©NGCS
Seminar - An Overview of Communications Technologies
Seminar - An Overview of Communications Technologies
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Seminar Overview Historical Perspective: Evolution of Telecommunications Technologies: In the 60s the telephone companies provided telephone and telegraph services. The telegraph service was a type of data communications service. The computer industry provided centralized computing and remote batch processing. The remote batch processing was the start of connecting remote company branches to the head office. The time-sharing companies also provided time-sharing computer services to their remote clients. The clients were connected via a data phone or dedicated line to the main computer. Most of the data transmission was in Asynchronous and Synchronous type. The customers leased the connecting facilities from the telephone company and the computer companies provided the total solution to the customer. Major computer companies, like IBM, DEC, HP, had proprietary protocols. The dominant protocols were IBM's Binary Synchronous (bi-Sync) Communications Procedure, Synchronous Digital Link Control (SDLC) Procedure and High-Level Data Link Control (HDLC) procedures to handle link interface equipment and communications circuits connecting two or more terminals that wish to communicate with the host computer. In the 70s, the demand for data phone and private Line services was growing very fast. The telephone companies saw an opportunity to develop facilities networks to meet the demand and lower their plant capital and operational costs. X.25 Protocol: In 1979, HDLC was adopted as an international standard by the International Standards Organization (ISO). The Comite Consultatif International Telegraphique et Telephonique CRTC), also known as International Telegraphy and Telephony Consultative Committee devised the X.25 standard packet switching architecture. The X.25 packets are similar to HDLC frames. The telephone companies, using their existing facilities network (Data Route), deployed the X.25 packet network (Data Pac) and moved some intelligence into the network. This helped medium and small-sized companies to get networking services from the telephone companies rather than having their own private networks. The telephone company facilities were very poor giving rise to too many errors in the data transmission, especially for high-speed (9600 bps +) data transmission. At the same time the telephone companies started implementing end-to-end digital (T-1) networks. At this stage, the data communications market was mushrooming and the demand from upper medium and large-sized companies was growing fast. Evolution of SONET: The private networks were growing at a rapid pace requiring very high speed links. The telephone companies saw this as a threat to their business and wanted a technology which could be used in their networks to entice the major corporations to use the telephone companies networks rather than developing their own private networks. The telephone companies came up with an optical fiber solution with Synchronous Optical Network (SONET) technology . Initially the SONET was implemented in the telephone company's Toll networks. The computer industry developed Fiber Distributed Data Interface, a high-speed networking technology, supporting 100 M bps user data over optical fiber rings. This was the computer industry's reply to the telephone company's SONET technology. A single optical fiber is capable of transmitting 10 G bps. The equipment manufacturers, like Nortel, increased the fiber data transmission capability by Wave Division Multiplexing (WDM) and Dense Wave Division Multiplexing (DWDM) technologies. Now a single optical strand is capable of carrying 160 G bps data. Radio technology was also widely used in the long distance network to carry voice traffic. At the same time the mobile radio systems and networks started growing to meet the voice communications needs of the mobile population. Most of the traffic was in analogue form with very little digital. Most of the digital was converted into analogue for transmission. The 1980s saw the birth of the communications equipment industry. The data set manufacturers started developing multiplexers (Asynchronous and Synchronous), Data Private Branch Exchanges (PBXs), Packet Assemblers and Disassemblers (PADs). Before that most of the communications equipment belonged to the major computer companies. Now, some of the intelligence from the networks moved to the communications equipment. New communications standards evolved. The deployment of optical fiber in the telephone networks improved the quality of transmission. The Bit Error Rate improved. At the same time the industry moved towards distributed intelligence. The corporations moved some functions away from the head office to the branch offices. The branch offices implemented their own computer systems and required high speed connections to the head office. As the Personal Computer evolved in the 1980s, the companies started implementing Local Area Networks. Evolution of Frame Relay and Cell Technologies: The traffic between the locations increased. Customers needed faster response times. The telephone companies packet networks were too slow. The computer industry came up with Frame Relay standards. The onus of checking some transmission functions moved to the computer systems. The telephone companies were relegated to providing facilities with limited network intelligence. This met Computer and Communication companies data communications needs. The telephone companies developed Asynchronous Transfer Mode (ATM) technology for transmitting multi-media (voice, data and video) information. By now the video and audio digitization technologies matured. Most of the information became digital. ATM technology, with a fixed-sized packet, reduced the information transmission delays in the network. The ATM standards were still in the developmental phase. The Frame Relay technology prospered but it lacked the voice transmission standards and speed. The telephone companies set-up Frame Relay networks and implemented the ATM technology in their high speed links linking large corporations Local Area Networks. The telephone companies also started deploying the ATM technology in the Metropolitan Area Networks to meet growing demand for video services from hospitals and connecting LANs and FDDI networks. Evolution of the Internet Technologies: The early 90s saw the birth of the Internet. The Internet network had T-1 lines in the core network. Initially customers used it as chat-lines to talk to other people of similar interest. As E-mail, Web-Sites, Home Pages, E-Commerce, research for information and voice communications on the Internet grew, the Frame Relay, ATM and SONET transmission technologies moved into the Internet network. The Internet is a happy partnership between the Computer, Communications and Telephone Industries. The present Internet has giga bps high speed links in the core network. Evolution of Convergence Technologies: The networks with the high speed transmission technologies were inadequate to carry voice and video along with data. The characteristics of voice and video traffic are real-time and different than data. Multi media technologies were required to digitize, and transmit on a priority basis the voice and video traffic. The convergence technologies added voice communications capability to the LANs taking some market away from the telephone companies. The Internet technology put pressure on the communications industry to develop 100 M bps and 1000 M bps LANs, IP-based phones and IP-based PABXs to carry digitized voice and video traffic. The QoS technologies also developed to monitor the communications networks. H.323, Session Initiation Protocol (SIP) and Media Gateway Control Protocol MGCP) convergence protocols were developed by the computer industry for LANs to carry multi-media traffic. The telephone industry has developed Megaco, a version of MGCP protocol. The telephone companies are planning to develop Megaco along with SIP in their telephone network to carry multi-media traffic, Evolution of the Cable Technologies: The Cable industry evolved from a one-way analog video transmission for TV signals to a two-way digital signal transmission. The Cable network infrastructure deployed SONET rings. The network provides TV and Internet services and is capable of providing voice services. The cable companies have developed Network-based Call Signaling Packet Cable Protocol (NCS PacketCable) for multi-media applications. Evolution of the Wireless Technologies: The wireless networks have evolved from a Mobile Radio system for voice to a Cellular system for voice, data and photos. Internet services are available on the network. The wireless also has Wi-Fi (802.11 a, b, g) technologies for Local Area Networks. The Local Multi Point Distribution System (LMDS) and Multi-channel Microwave Distribution Service (MMDS) technologies provide customers with multi-media services. Overview of the Seminar: The telecommunications and IT industries are undergoing tremendous changes. These changes are driven by the new technologies and user demands for sophisticated services. This seminar provides a high-level overview of the current and evolving technologies. By understanding various options professionals will be in a position to capitalize on the opportunities that are presented by the technologies. Upon completion of this seminar you will learn about: - The factors changing the landscape of communications industry - The continuous battle between the computer, communications and
telephone - Frame Relay, 802.6, ATM technologies - Optical communications technologies (SONET, WDM, DWDM) - Internet architecture, TCP/IP, Web Services and applications - Convergence technologies (H.323, SIP, MGCP, Megaco, MPLS, NCS PacketCable) - Wireless technologies (1st, 2nd, 3rd, 4th Generation) - Cable network architecture - Telephone network architecture - North American and European data communications transmission standards - FDDI,100 M bps LANs, 1000 M bps LANs and 802.11 (a, b and g) - Strengths and weaknesses of communications technologies - Technologies and networks suited to your enterprise applications _________________ __________
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