The 1990s were an explosive decade in every aspect of networking, and we can only touch on a few highlights here. Ethernet continued to evolve as a LAN technology and began to eclipse competing technologies such as Token Ring and FDDI. In 1991, Kalpana Corporation began marketing a new form of bridge called a LAN switch, which dedicated the entire bandwidth of a LAN to a single port instead of sharing it among several ports. Later known as Ethernet switches or Layer 2 switches, these devices quickly found a niche in providing dedicated high-throughput links for connecting servers to network backbones. Layer 3 switches soon followed, eventually displacing traditional routers in most areas of enterprise networking except for WAN access. Layer 4 and higher switches are now popular
in server farms for load balancing and fault tolerance purposes.
The rapid evolution of the PC computing platform and the rise of bandwidth-hungry applications created a need for something faster than 10-Mbps Ethernet, especially on network backbones. The first full-duplex Ethernet products, offering speeds of 20 Mbps, became available in 1992. In 1995 work began on a standard for full-duplex Ethernet; it was finalized in 1997. A more important development was Grand Junction Networks' commercial Ethernet bus, introduced in 1992, which functioned at 100 Mbps. Spurred by this advance, the 802.3 group produced the 802.3u 100BaseT Fast Ethernet standard for transmission of data at 100 Mbps over both twisted-pair copper wiring and fiber-optic cabling.
Although the jump from 10-Mbps to 100-Mbps Ethernet took almost 15 years, a year after the 100BaseT Fast Ethernet standard was released, work began on a 1000-
Mbps version of Ethernet popularly known as Gigabit Ethernet (GbE). Fast Ethernet was beginning to be deployed at the desktop, and this was putting enormous strain on the FDDI backbones that were deployed on many commercial and university campuses. FDDI also operated at 100 Mbps (or 200 Mbps if fault tolerance was discarded in favor of carrying traffic on the redundant ring), so a single Fast Ethernet desktop connection could theoretically saturate the capacity of the entire network backbone. Asynchronous Transfer Mode (ATM), a broadband cell-switching technology used primarily in telecommunication/WAN environments, was briefly considered as a possible successor to FDDI for backboning Ethernet networks together, and LAN emulation (LANE) was developed to carry LAN traffic such as Ethernet over ATM. However, ATM is much more complex than Ethernet, and a number of companies saw extending Ethernet speeds to 1000 Mbps as a way to provide network backbones with much greater capacity using technology that most network administrators were already familiar with. As a result, the 802 group called 802.3z developed a GbE standard called 1000BaseX, which it released in 1998. Today GbE is the norm for LAN backbones, and Fast Ethernet is becoming ubiquitous at the desktop level. Work is even underway on extending Ethernet technologies to 10 gigabits per second (Gbps). A competitor of GbE for high-speed collapsed backbone interconnects, called Fibre Channel, was conceived by an ANSI committee in 1988 but is used mainly for storage area networks (SANs).
The 1990s saw huge changes in the landscape of telecommunications providers and their services. "Convergence" became a major buzzword, signifying the combining of voice, data, and broadcast information into a single medium for delivery to businesses and consumers through broadband technologies such as metropolitan Ethernet, Digital Subscriber Line (DSL), and cable modem systems. The cable modem was introduced in 1996, and by the end of the decade broadband residential Internet access through cable television systems had become a strong competitor with telephone-based systems such as Asymmetric Digital Subscriber Line (ADSL) and G.Lite, another variant of DSL.
Also in the 1990s, Voice over IP (VoIP) emerged as the latest "Holy Grail" of networking and communications and promised businesses huge savings by routing voice telephone traffic over existing IP networks. VoIP technology works, but the bugs are still being ironed out and deployments remain slow. Recent developments in VoIP standards, however, may help propel deployment of this technology in coming years.
The first public frame relay packet-switching services were offered in North America in 1992. Companies such as AT&T and Sprint installed a network of frame relay nodes across the United States in major cities, where corporate networks could connect to the service through their local telco. Frame relay began to eat significantly into the deployed base of more expensive dedicated leased lines such as the T1 or E1 lines that businesses used for their WAN solutions, resulting in lower prices for these leased lines and greater flexibility of services.
In Europe frame relay has been deployed much more slowly, primarily because of the widespread deployment of packet-switching networks such as X.25.
The Telecommunications Act of 1996 was designed to spur competition in all aspects of the U.S. telecommunications market by allowing the RBOCs access to long-distance services and IXCs access to the local loop. The result has been an explosion in technologies and services offered by new companies called competitive local exchange carriers (CLECs), with mergers and acquisitions changing the nature of the service provider landscape almost daily.
The 1990s saw a veritable explosion in the growth of the Internet and the development of Internet technologies. As mentioned earlier, ARPANET was replaced in 1990 by NSFNET, which by then was commonly called the Internet. At the beginning of the 1990s, the Internet's backbone consisted of 1.544-Mbps T1 lines connecting various institutions, but in 1991 the process
of upgrading these lines to 44.735-Mbps T3 circuits began. By the time the Internet Society (ISOC) was chartered in 1992, the Internet had grown to an amazing 1 million hosts on almost 10,000 connected networks. In 1993 the NSF created Internet Network Information Center (InterNIC) as a governing body for DNS. In 1995 the NSF stopped sponsoring the Internet backbone and NSFNET went back to being a research and educational network. Internet traffic in the United States was routed through a series of interconnected commercial network providers.
The first commercial Internet service providers (ISPs) emerged in the early 1990s when the NSF removed its restrictions against commercial traffic on the NSFNET. Among these early ISPs were Performance Systems International (PSI), UUNET, MCI, and Sprintlink. (The first public dial-up ISP was actually The World, with the URL www.world.std.com.) In the mid-1990s, commercial online networks such as AOL, CompuServe, and Prodigy provided gateways to the Internet to subscribers. Later in the decade, Internet deployment grew exponentially, with personal Internet accounts proliferating by the tens of millions around the world, new technologies and services developing, and new paradigms evolving for the economy and business. It would take a whole book to talk about all the ways the Internet has changed our lives.
Many Internet technologies and protocols have come and gone quickly. Archie, an FTP search engine developed in 1990, is hardly used today. The WAIS protocol for indexing, storing, and retrieving full-text documents, which was developed in 1991, has been eclipsed by Web search technologies. Gopher, which was created in 1991, grew to a worldwide collection of interconnected file systems, but most Gopher servers have now been turned off. Veronica, the Gopher search tool developed in 1992, is obviously obsolete as well. Jughead later supplemented Veronica but has also become obsolete. (There never was a Betty.)
The most obvious success story among Internet protocols has been HTTP, which, with HTML and the system of URLs for addressing, has formed the basis of the Web. Tim Berners-Lee and his colleagues created the first Web server (whose fully qualified DNS name was info.cern.ch) and Web browser software using the NeXT computing platform that was developed by Apple pioneer Steve Jobs. This software was ported to other platforms, and by the end of the decade more than 6 million registered Web servers were running, with the numbers growing rapidly.
Lynx, a text-based Web browser, was developed in 1992. Mosaic, the first graphical Web browser, was developed in 1993 for the UNIX X Windows platform by Marc Andreessen while he was a student at the National Center for Supercomputing Applications (NCSA). At that time, there were only about 50 known Web servers, and HTTP traffic amounted to only about 0.1 percent of the Internet's traffic. Andreessen left school to start Netscape Communications, which released its first version of Netscape Navigator in 1994. Microsoft Internet Explorer 2 for Windows 95 was released in 1995 and rapidly became Netscape Navigator's main competition. In 1995, Bill Gates announced Microsoft's wide-ranging commitment to support and enhance all aspects of Internet technologies through innovations in the Windows platform, including the popular Internet Explorer Web browser and the Internet Information Server (IIS) Web server platform of
Windows NT. Another initiative in this direction was Microsoft's announcement in 1996 of its ActiveX technologies, a set of tools for active content such as animation and multimedia for the Internet and the PC.
In cellular communications technologies, the 1990s were clearly the "digital decade." The work of the TIA resulted in 1991 in the first standard for digital cellular communication, the TDMA Interim Standard 54 (IS-54). Digital cellular was badly needed because the analog cellular subscriber market in the United States had grown to 10 million subscribers in 1992 and 25 million subscribers in 1995. The first tests of this technology, based on Time Division Multiple Access (TDMA) technology, took place in Dallas, Texas, and in Sweden, and were a success. This standard was revised in 1994 as TDMA IS-136, which is commonly referred to as Digital Advanced Mobile Phone Service (D-AMPS).
Meanwhile, two competing digital cellular standards also appeared. The first was the CDMA IS-95 standard for CDMA cellular systems based on spread spectrum technologies, which was first proposed by QUALCOMM in the late 1980s and was standardized by the TIA as IS-95 in 1993. Standards preceded implementation, however; it was not until 1996 that the first commercial CDMA cellular systems were rolled out.
The second system was the Global System for Mobile Communication (GSM) standard developed in Europe. (GSM originally stood for Groupe Spéciale Mobile.) GSM was first envisioned in the 1980s as part of the movement to unify the European economy, and the European Telecommunications Standards Institute (ETSI) determined the final air interface in 1987. Phase 1 of GSM deployment began in Europe in 1991. Since then, GSM has become the predominant system for cellular communication in over 60 countries in Europe, Asia, Australia, Africa, and South America, with over 135 mobile networks implemented. However, GSM implementation in the United States did not begin until 1995.
In the United States, the FCC began auctioning off portions of the 1900-MHz frequency band in 1994. Thus began the development of the higher-frequency Personal Communications System (PCS) cellular phone technologies, which were first commercially deployed in the United States in 1996.
Establishment of worldwide networking and communication standards continued apace in the 1990s. For example, in 1996 the Unicode character set, a character set that can represent any language of the world in 16-bit characters, was created, and it has since been adopted by all major operating system vendors.
In client/server networking, Novell in 1994 introduced Novell NetWare 4, which included the new Novell Directory Services (NDS), then called NetWare Directory Services. NDS offered a powerful tool for managing hierarchically organized systems of network file and print resources and for managing security elements such as users and groups. NetWare is now in version 6 and NDS is now called Novell eDirectory.
In other developments, the U.S. Air Force launched the twenty-fourth satellite of the Global Positioning System (GPS) constellation in 1994, making possible precise terrestrial positioning using handheld satellite communication systems. RealNetworks released its first software in 1995, the same year that Sun Microsystems announced the Java programming language, which has grown in a few short years to rival C/C++ in popularity for developing distributed applications. Amazon.com was launched in 1995 and has become a colossus of cyberspace retailing in a few short years. Microsoft WebTV, introduced in 1997, is beginning to make inroads into the residential Internet market.
Finally, the 1990s were, in a very real sense, the decade of Windows. No other technology has had as vast an impact on ordinary computer users as Windows, which brought to homes and workplaces the power of PC computing and the opportunity for client/server computer networking. Version 3 of Windows, which was released in 1990, brought dramatic increases in performance and ease of use over earlier versions, and Windows 3.1, released in 1992, quickly became the standard desktop operating system for both corporate and home users. Windows for Workgroups 3.1 quickly followed that same year. It integrated networking and workgroup functionality directly into the Windows operating system, allowing Windows users to use the corporate computer network for sending e-mail, scheduling meetings, sharing files and printers, and performing other collaborative tasks. In fact, it was Windows for Workgroups that brought the power of computer networks from the back room to users' desktops, allowing them to perform tasks previously possible only for network administrators.
In 1992, Microsoft released the first beta version of its new 32-bit network operating system, Windows NT. In 1993 came MS-DOS 6, as Microsoft continued to support users of text-based computing environments. That was also the year that Windows NT and Windows for Workgroups 3.11 (the final version of 16-bit Windows) were released. In 1995 came the long-awaited release of Windows 95, a fully integrated 32-bit desktop operating system designed to replace MS-DOS, Windows 3.1, and Windows for Workgroups 3.11 as the mainstream desktop operating system for personal computing. Following in 1996 was Windows NT 4, which included enhanced networking services and a new Windows 95-style user interface. Windows 95 was superseded by Windows 98 and later by Windows Millennium Edition (Me).
At the turn of the millennium came the long-anticipated successor to Windows NT, the Windows 2000 family
of operating systems, which includes Windows 2000 Professional, Windows 2000 Server, Windows 2000 Advanced Server, and Windows 2000 Datacenter Server. The Windows family has how grown to encompass the full range of networking technologies, from embedded devices and Personal Digital Assistants (PDAs) to desktop and laptop computers to heavy-duty servers running the most advanced, powerful, scalable, business-
critical, enterprise-class applications.
No comments:
Post a Comment