Stands for World Wide Web Consortium, a vendor- neutral organization created in 1994 that develops common, interoperable standards and protocols for the World Wide Web (WWW).
See Also World Wide Web Consortium (W3C)
Also called a faceplate, a cabling fixture attached to a wall in a work area for connecting computers to the network.
Overview
Wall plates are generally used in work areas to enable desktop computers to be connected to the network. The wall plates connect to the building's structured wiring system, and the computers connect to the wall plate by a short unshielded twisted-pair (UTP) cable called a drop cable.
Wall plates come in mono-port, dual-port, and quad- port configurations, generally with RJ-45 jacks, which resemble household RJ-11 telephone wall jacks but are larger and have more wires. These RJ-45 jacks are typically used when networks are running Ethernet or Fast Ethernet. Other less common types of jacks include SC jacks for networks that use fiber-optic cabling, and BNC jacks for legacy 10Base2 networks.
The back end of the jacks in a wall plate typically connect to a horizontal cable that runs inside the wall or through a false ceiling or floor. This horizontal table terminates at a patch panel in the wiring closet on that floor, and vertical cabling running through elevator shafts or vertical rises connects wiring on different floors to switches in the main equipment room in the basement.
Implementation
Wall plates are an important feature of a permanent networking installation because they enable stations to be easily disconnected and reconnected to the network and protect network cables from damage caused by physical handling. The most common type are flush wall plates, which are flat like AC outlets, but angled wall plates are often a better choice because they offer better protection from excessive cable bending and protect drop cables from damage by contact with heavy or sharp- edged furniture.
Be sure to label or number wall plates so that you can easily identify the port on the patch panel to which they connect. If you cannot run cabling inside walls and must instead tack cabling directly onto the interior wall surface, use surface-mount boxes instead of wall plates. These are box-shaped adapters that screw onto the wall and have side or face jacks for connecting cables.
Wall plate. Examples of flush and angled wall plates.
Notes
You can also get special wall plates for serial interfaces that use DB connectors such as DB9 or DB25. These wall plates are used in mainframe computing environments in which dumb terminals are connected to mainframe hosts by using RS-232 serial lines.
See Also cabling , drop cable ,premise cabling ,RJ connectors ,structured wiring ,
Stands for wide area network, a geographically distributed network composed of multiple local area networks (LANs) joined into a single large network using services provided by telecommunication carriers.
See Also wide area network (WAN)
Services offered by telecommunication carriers to enable companies to build wide area networks (WANs).
Overview
WAN services are generally provided to enterprises by telcos, usually either by Regional Bell Operating Companies (RBOCs) or inter-exchange carriers (IXCs). The range of different types of WAN services that telcos can offer includes
Dedicated or leased lines: These services establish a permanent point-to-point connection between two locations. They are always "on" and ready to carry network traffic. Leased lines are typically expensive because telco switches must be dedicated to the customer even when they are not being used. Examples of leased line services include T-carrier services such as T1, fractional T1, and T3. Leased lines are most popular with large enterprises that need reliable, high-bandwidth WAN links between branch offices.
Circuit-switched services: These services establish a temporary path through the carrier's network, usually only lasting as long as the call. When the session is terminated, the carrier's switches are then freed up for other customers to use. Examples of circuit-switched services include Integrated Services Digital Network (ISDN) and dial-up modem connections using the Public Switched Telephone Network (PSTN). One problem with using circuit- switched services is that the quality of transmission depends on the switches and trunk lines used and therefore varies from call to call. For this reason, circuit-switched services are typically used for backup in case a leased line goes down. Because circuit-switched services also cost much less than leased lines, they are frequently used in low-traffic WAN networking environments.
Packet-switched services: These services use virtual circuits instead of end-to-end physical connections. Data is transmitted in packets across a public data network (PDN) owned by the carrier (which is really a misnomer, as the network is owned privately). Examples of packet-switching services include frame relay and X.25.
Cell-switched services: This is similar to packet- switching but employs small fixed-size cells instead of variable-size packets. Asynchronous Transfer Mode (ATM) is a popular cell-switching technology used in high-end enterprise WAN services. Connectivity at the customer premises is usually provided using an integrated access device (IAD) or router.
The WAN environment has been changing radically in recent years. Although enterprises have traditionally relied on T1 or frame relay for most branch-office connectivity solutions, several new solutions have emerged that can offer considerable cost savings and ease of use over standard WAN solutions. These new technologies include
Digital Subscriber Line (DSL): A family of different technologies for transmitting data over existing copper local loop wiring at T1 speeds or higher. DSL circumvents the cost of deploying expensive conditioned T1 lines and is a much cheaper solution than T1, but it has not yet achieved the same degree of reliability. Nevertheless, many enterprises are eying this new technology carefully in consideration of future WAN deployments.
Virtual private network (VPN): Using the public Internet for securely carrying private Internet Protocol (IP) traffic between different locations. Any kind of Internet connection can be used for a VPN, including dial-up, DSL, and T1. The advantage here is that data can be carried long distances without any added cost since a public network carries the traffic instead of a carrier's private network.
IP over ATM over SONET: This technology transports Internet Protocol (IP) traffic using ATM as the Layer 2 (data link layer) protocol and Synchronous Optical Network (SONET) as the underlying Layer 1 (physical layer) transport. The main problem with this solution is the "cell tax," the intrinsic overhead involved in translating IP packets into ATM cells, which can be as high as 13 percent of the throughput-or even higher.
Packet over SONET: Also known as IP over SONET or IP over PPP over SONET, this technology replaces Layer-2 ATM with Point-to-Point Protocol (PPP) encapsulation.
Metropolitan Ethernet: Here carriers run Gigabit Ethernet (GbE) connections right to the customer premises using fiber-optic cabling, which are then typically connected to a metropolitan area network (MAN) dual SONET ring.
Fixed wireless: Buildings too far from a telco central office (CO) to deploy fiber for high-speed WAN links can find an alternative in fixed wireless networking technologies such as Local Multipoint Distribution System (LMDS), Multichannel Multipoint Distribution System (MMDS), microwave systems, or even point-to-point infrared laser transmission. Satellite networking is another emerging option, but its use is limited due to the high latencies involved.
See Also Asynchronous Transfer Mode (ATM) , circuit-switched services ,Digital Subscriber Line (DSL) ,frame relay ,Gigabit Ethernet (GbE) ,Integrated Access Device (IAD) ,Integrated Services Digital Network (ISDN) ,inter-exchange carrier (IXC) ,Internet Protocol (IP) ,leased line ,Local Multipoint Distribution Service (LMDS) ,metropolitan Ethernet ,Multipoint Multichannel Distribution Service (MMDS) ,packet-switching services ,Point-to-Point Protocol (PPP) ,Public Switched Telephone Network (PSTN) ,Regional Bell Operating Company (RBOC) ,Synchronous Optical Network (SONET) ,T-carrier ,telco ,virtual private network (VPN) , X.25
Stands for Wireless Application Protocol, a technology for implementing mobile devices with the Web.
See Also Wireless Application Protocol (WAP)
Transmitting multiple bitstreams down a single strand of fiber-optic cabling using different colors (wavelengths) for each stream.
Overview
Wavelength division multiplexing (WDM) was developed in the late 1980s as a way of increasing the carrying capacity of fiber-optic cabling. Inter-exchange carriers (IXCs) such as AT&T, Sprint Corporation, and Worldcom began implementing WDM in the mid- 1990s when it became apparent that the rapid growth of the Internet would soon stress the carrying capacity of long-haul trunk lines. Telcos now turn to WDM as a standard solution when traffic congestion grows on backbone carrier networks.
WDM allows two or more separate bitstreams to be beamed down a strand of fiber using lasers of different frequencies, usually 10 nanometers or more apart in frequency. Each data stream itself can carry multiple data sessions by dividing the stream into different time slots using time-division multiplexing (TDM). WDM thus employs two forms of multiplexing: frequency-division multiplexing (FDM) to create different light paths and TDM to enable each light path to carry multiple data streams.
WDM supports common physical layer technologies used by telcos, including Synchronous Optical Network (SONET) and Asynchronous Transfer Mode (ATM). Although early WDM systems only supported 2 light channels, versions have been developed that support 4, 8, 16, and even 32 or more separate channels. WDM can operate over distances up to about 30 miles (50 kilometers), and this can be extended to hundreds of kilometers using optical repeaters.
Notes
A newer version of this technology called dense wavelength division multiplexing (DWDM) is essentially WDM on steroids and is basically WDM where the wavelength separation between adjacent channels is 2 nanometers or less, potentially resulting in hundreds of channels being carried over a single strand of fiber and throughput in excess of 1 terabit per second.
See Also Asynchronous Transfer Mode (ATM) ,dense wavelength division multiplexing (DWDM) ,fiber-optic cabling ,frequency-division multiplexing (FDM) ,inter-exchange carrier (IXC) ,Synchronous Optical Network (SONET) ,time-division multiplexing (TDM)
Stands for Web-Based Enterprise Management, a set of technologies for developing standards-based network management platforms.
See Also Web-Based Enterprise Management (WBEM)
Stands for Wideband Code Division Multiple Access and known as Universal Mobile Telecommunications System (UMTS) in Europe, a worldwide standard for a third-generation (3G) cellular communications system.
See Also Wideband Code Division Multiple Access (W-CDMA)
Stands for wavelength division multiplexing, transmitting multiple data streams down a single strand of fiber-optic cabling using different colors (wavelengths) for each stream.
See Also wavelength division multiplexing (WDM)
Short for World Wide Web, the popular Internet service that is rapidly changing the way we live and work.
See Also World Wide Web (WWW)
A collection of elements on a Web site that performs a task programmatically.
Overview
Web applications are applications that are designed to run on Web servers and are accessed through Web browsers. Web applications may be implemented as client/server, multi-tier, or peer-to-peer applications. A common example of a Web application is the ordering mechanism or "shopping cart" on an e-commerce site such as Amazon.com.
Web applications can be developed by using a variety of technologies, including the following:
Active Server Pages (ASP)
ActiveX components or Java applets
Internet Server API (ISAPI)
Perl scripting using Common Gateway Interface (CGI)
See Also Active Server Pages (ASP) , ActiveX ,Common Gateway Interface (CGI) ,Internet Server API (ISAPI) ,Java ,
A set of technologies for developing standards-based network management platforms.
Overview
Web-Based Enterprise Management (WBEM) was developed by the Distributed Management Task Force (DMTF), which originated in 1996 as a joint initiative of companies headed by Microsoft Corporation, Intel Corporation, Cisco Systems, Compaq Computer Corporation, and BMC Software. WBEM was designed to help bring order to the chaos of the enterprise network management marketplace with its proprietary solutions and platforms. WBEM provides a framework of application programming interfaces (APIs), an object model, and a syntax for developing network management solutions that are interoperable between vendors.
Web-Based Enterprise Management. The architecture of the WBEM framework.
WBEM is designed to work in heterogeneous enterprise networking environments to collect diagnostic and management data relating to hardware from multiple vendors, different operating systems, different network protocols, and distributed applications. WBEM enables information such as the amount of RAM in a computer, the capacity of a hard disk, the type of process, and the version of the operating system or firmware to be extracted from computers, routers, switches, and other network devices. This information can be used to detect potential problems before they occur, for remote management purposes, and for planning and other decision-making purposes.
WBEM simplifies management by providing a common model and data source that can be extended to function with existing protocols, networking components, and applications. An important part of the WBEM framework for WBEM is the Common Information Model (CIM), a set of schemas for cross- platform network management also developed by the DMTF. Once network management information is collected and stored in the CIM repository, it can be shared across an enterprise and displayed using WBEM management systems. Using CIM, a WBEM management application can access network information using Simple Network Management Protocol (SNMP), Desktop Management Interface (DMI), and other sources such as the Windows registry.
Microsoft has built the WBEM architecture into its Windows 2000, Windows XP, and Windows .NET Server platforms in the form of Windows Management Instrumentation (WMI), Microsoft's implementation of WBEM for 32-bit Microsoft Windows platforms.
For More Information
Find out more about WBEM at www.dmtf.org/wbem.
See Also Common Information Model (CIM) , Desktop Management Interface (DMI) ,Distributed Management Task Force (DMTF) ,Simple Network Management Protocol (SNMP) ,
A client-side Hypertext Transfer Protocol (HTTP) application.
Overview
Web browsers enable users to access content published on Web servers that reside on the Internet or corporate intranets. Web browsers request and receive content hosted on Web servers using HTTP, the standard application layer protocol for the World Wide Web (WWW). Such content can be static, meaning it consists of text files formatted using Hypertext Markup Language (HTML), or the content can be dynamic, meaning it is generated on demand using server-side or client-side scripting technologies such as Microsoft Active Server Pages (ASP) and JavaScript.
Web browsers typically include features to make "browsing" (locating and accessing resources on) the Web simple, including
Toolbar buttons for navigating forward and backward through the tree of previously displayed pages, for stopping the download process, and for manually refreshing a page that loaded incompletely.
Lists of favorites or bookmarks that store Uniform Resource Locators (URLs) of frequently accessed sites as well as tools for organizing and accessing those URLs.
Options for specifying a default home page from which to begin browsing, a default search engine for searching the Web, and other default browsing options.
Security options for handling such concerns as whether to allow scripts, ActiveX components, or Java applets to run on the browser.
Facilities for displaying a page's underlying source code or HTML and even for editing and publishing Web content.
Integration with other Internet software such as mail, news, or chat applications. Some Web browsers are packaged as stand-alone applications, while others are part of an overall suite of Internet tools that are integrated at various levels.
History
The first graphical Web browser was developed in 1993 by a group of students headed by Marc Andreessen at the National Center for Supercomputing Applications (NCSA). This browser was known as Mosaic and was distributed free. In 1994, Andreessen left NCSA to help found Netscape Communications, which developed the Netscape Navigator browser. The popularity of this browser helped foster the explosive growth of the Internet in the mid-1990s.
Microsoft quickly entered the arena with its Internet Explorer browser, which has since become the most widely used browser in the marketplace. Starting with Microsoft Windows 95, Microsoft began integrating Internet Explorer into its Windows operating systems, with the result that users running Windows can access Internet resources as easily as files on their own hard drives.
Web browsers have now become a standard interface for a wide range of platforms and services, including messaging, network management, mainframe access, and many other enterprise applications. The Web browser can be thought of a kind of "universal client" that is simple to learn and use, yet powerful enough to handle the most complex programming environments.
See Also Active Server Pages (ASP) , ActiveX ,Hypertext Markup Language (HTML) ,Hypertext Transfer Protocol (HTTP) ,Internet Explorer ,Java ,JavaScript ,
Also called a Layer 7 switch or URL switch, an Ethernet switch that forwards frames according to Layer 4 or higher header information and used primarily for directing and load-balancing Web traffic.
See Also Layer 7 switch
Hosting of Web content by service providers.
Overview
Companies offering Web hosting services range from local Internet service providers (ISPs) who provide businesses with a few dozen megabytes of server space and access to Perl scripting engines to global companies with server farms that offer dedicated servers, e-mail accounts, domain name holding, Microsoft FrontPage support, open database connectivity (ODBC) support, domain name hosting and holding services, and other services. Some industry analysts estimate that about two-thirds of all corporate Web sites are hosted by Web hosting service providers.
Web hosting started to become big business around 1998 and service providers offering Web hosting services reached their heyday in early 2000. Since then Web hosting providers have been rapidly supplanted by "content hosting" providers that offer an even greater range of services, which can include back-end system integration, custom programming, security management, and site mirroring. However, the distinction between the terms Web hosting and content hosting is often blurred in this rapidly evolving market.
Web hosting providers generally offer three different kinds of hosting services:
Shared hosting: Your site is running on a Web server owned by the hosting provider, but the server hosts other people's sites as well.
Dedicated hosting: Your site is running on a Web server owned by the hosting provider and your company has exclusive use of that server.
Colocated hosting: You configure your Web server and then bring it in to the hosting provider's data center and they connect it to their high-speed Internet backbone.
When shopping for a Web hosting or content hosting service provider, it is a good idea to find out what degree of availability they guarantee. Many providers offer 99.99 percent availability with no downtime and give clients a refund if any downtime occurs, even if it is only a few minutes. They ensure such levels of availability by hosting sites on multiple redundant servers and scheduling maintenance so that one server is always online. It is also a good idea to make sure that the provider offers the full range of services that you require (or might soon require), such as database access and site mirroring. Find out the size of the pipe connecting the provider with the Internet backbone and at which point of presence (POP) the provider is connected to the Internet. For business hosting purposes, a minimum dual OC3 connection with guaranteed 155-megabits per second (Mbps) throughput is recommended. Decide whether you want dedicated or shared hosting-that is, whether you are willing to share a server and its network bandwidth with other companies or whether you require the stability, reliability, and throughput of your own dedicated Web server.
See Also Internet service provider (ISP) ,
A file of text information formatted using Hypertext Markup Language (HTML).
Overview
Web pages are sent by Web servers in response to requests from Web browsers and can contain formatted text, images, scripts, and various forms of active content. Web pages are generally of two types:
Static: Stored as files on the server in the same form that they are delivered to the client. These files usually have the extension .htm or .html.
Dynamic: Pages that include scripts, ActiveX components, Java applets, Dynamic HTML (DHTML), and other forms of active content to make static pages more interesting or useful. Dynamic pages often do not actually exist on the server until the client requests them, whereupon they are generated by the server using Active Server Pages (ASP) or some other server-side scripting technology.
See Also Active Server Pages (ASP) , ActiveX ,Dynamic HTML (DHTML) ,Hypertext Markup Language (HTML) ,Internet ,Java ,scripting ,
A server-side Hypertext Transfer Protocol (HTTP) application.
Overview
Web servers enable the publishing content on the Internet or on corporate intranets. Web servers host Web pages and other content that can be delivered using HTTP to Web browsers and other clients.
The first Web servers were originally developed for the UNIX platform and were used for publishing static Web content consisting of text files formatted using Hypertext Markup Language (HTML). To enhance static Web pages, dynamic features such as forms were later added using scripts written in interpretive languages such as Perl that ran within the UNIX Common Gateway Interface (CGI) execution environment. Other technologies developed later for delivering dynamic Web content include Java applets, ActiveX controls, Microsoft Active Server Pages (ASP) server-side scripting, and many others.
Marketplace
Some of the big players in the Web server arena include
Microsoft Internet Information Server (IIS): A component of the Windows 2000 and Windows .NET Server platforms, IIS is a popular development platform for Internet applications that supports HTTP, File Transfer Protocol (FTP), Simple Mail Transfer Protocol (SMTP), Network News Transfer Protocol (NNTP), Secure Sockets Layer (SSL), Secure/Multipurpose Internet Mail Extensions (S/MIME), and other Internet standard protocols. IIS also supports Microsoft FrontPage, a popular Web site development tool.
iPlanet Web Server: Formerly Netscape Enterprise Server, iPlanet is a robust Web platform that runs on a variety of platforms and is widely used in enterprise environments.
Apache: An open source application developed originally for the UNIX platform, Apache is popular with the Internet service provider (ISP) community that originated within the academic environment where the Internet originated.
Lotus Domino: The Web server component of IBM's Lotus Notes messaging and collaboration platform.
Industry surveys have indicated that Apache is the predominant player when it comes to hosting public Internet sites, but an industry survey in 2001 indicated that IIS was the most popular Web server platform in Fortune 1000 companies, with 48 percent of respondents using IIS, 24 percent using iPlanet, 18 percent using Apache, and the rest using Domino or other platforms. The iPlanet platform is also used by 7 of the top 10 Fortune 1000 companies.
See Also Active Server Pages (ASP) , ActiveX ,Apache ,Common Gateway Interface (CGI) ,Hypertext Transfer Protocol (HTTP) ,Internet ,Internet Information Services (IIS) ,Java ,
Providing access to legacy mainframe and midframe host systems to client systems using a standard Web browser interface.
Overview
Web-to-host technologies enable large companies to leverage their existing investment in IBM S/390 mainframe and AS/400 midframe host systems to gain advantage in the e-business and e-commerce arena. Host systems are widely used in enterprises for database hosting and transactional processing, and providing easy access to resources on host systems can give companies a competitive edge in the Internet economy. In the client/server computing era, special host client software displaced legacy "dumb terminals" by providing 3270 and 5250 terminal emulation on standard PCs. Web-to-host takes this process a step further by providing ActiveX or Java applets that allow terminal emulation sessions to run within a standard Web browser interface, making it as easy to access host resources as it is to browse the Web.
Web-to-host. Example of how Web-to-host integration can be implemented.
Implementation
Web-to-host platforms work in two basic ways:
Direct connection: These platforms provide a direct connection between resources on the host and client Web browsers. Session security is usually provided by the host itself. This security is needed as traditional 3270 and 5250 terminal emulation clients communicate with hosts in clear-text data streams, and this is unacceptable when using the public Internet as the transmission medium.
Web server: Here a Web server acts as a gateway between the host and browser client. The gateway typically provides security by encrypting the data stream, usually using Secure Sockets Layer (SSL) encryption.
In the second approach, the Web-to-host product, such as Microsoft Host Integration Server, communicates with the host system using Systems Network Architecture (SNA) and with the Web server using a programmatic technology such as Microsoft Corporation's Internet Server API (ISAPI) or various scripting technologies. The Web server then communicates with the browser client using standard Hypertext Transfer Protocol (HTTP), which is typically augmented with ActiveX controls or Java applets for greater display functionality.
Marketplace
Besides Microsoft's own Host Integration Server platform, a number of popular Web-to-host integration products are available in the marketplace. A popular solution is WebSphere Host OnDemand from IBM, which provides advanced display and printer emulation, integrated security, and enhanced database support. Some other popular products include WEB-ifier by Anota, e-Vantage Host Access Server by Attachmate Corporation, HostExplorer by Hummingbird International, HostFront by Farabi Technology Corporation, Novation by GT Software, WebConnect by OpenConnect Systems, Rumba by NetManage, WinSurf Mainframe Access by ICOM Infomatics, and Reflection by WRQ.
Notes
When shopping for a Web-to-host solution, look for the following features:
Enhanced input and display features such as resizable terminal windows, custom screen colors, keyboard mapping, and macros
3270 and 5250 printer emulation to enable jobs run on hosts to print to local printers instead of remote host-connected ones
Centralized deployment and management of host-client connections
SSL encryption for data stream security
See Also 3270 , 5250 ,ActiveX ,AS/400 ,Host Integration Server ,Hypertext Transfer Protocol (HTTP) ,Internet Server API (ISAPI) ,Java ,mainframe ,scripting ,Secure Sockets Layer (SSL) ,Systems Network Architecture (SNA) ,terminal emulator ,
Transmission Control Protocol (TCP) or User Datagram Protocol (UDP) port numbers that have been assigned to specific Transmission Control Protocol/Internet Protocol (TCP/IP) applications or services by the Internet Assigned Numbers Authority (IANA).
Overview
Well-known port numbers are assigned from the range 0 through 1023 from a total possible range of port numbers 0 through 65535. The following table lists many of the well-known port numbers.
Port Number | Keyword | Description |
0/tcp, udp | Reserved | |
1/tcp, udp | tcpmux | TCP Port Service Multiplexer |
2/tcp, udp | compressnet | Management Utility |
3/tcp, udp | compressnet | Compression Process |
4/tcp, udp | Unassigned | |
5/tcp, udp | rje | Remote Job Entry |
6/tcp, udp | Unassigned | |
7/tcp, udp | echo | Echo |
8/tcp, udp | Unassigned | |
9/tcp, udp | discard | Discard; alias = sink null |
10/tcp, udp | Unassigned | |
11/tcp, udp | systat | Active Users; alias = users |
12/tcp, udp | Unassigned | |
13/tcp, udp | daytime | Daytime |
14/tcp, udp | Unassigned | |
15/tcp, udp | Unassigned (was netstat) | |
16/tcp, udp | Unassigned | |
17/tcp, udp | qotd | Quote of the Day; alias = quote |
18/tcp, udp | msp | Message Send Protocol |
19/tcp, udp | chargen | Character Generator; alias = ttytst source |
20/tcp, udp | ftp-data | File Transfer (default data) |
21/tcp, udp | ftp | File Transfer (control), connection dialog |
22/tcp, udp | Unassigned | |
23/tcp, udp | telnet | Telnet |
24/tcp, udp | Any private mail system | |
25/tcp, udp | smtp | Simple Mail Transfer; alias = mail |
26/tcp, udp | Unassigned | |
27/tcp, udp | nsw-fe | NSW User System FE |
28/tcp, udp | Unassigned | |
29/tcp, udp | msg-icp | MSG ICP |
30/tcp, udp | Unassigned | |
31/tcp, udp | msg-auth | MSG Authentication |
32/tcp, udp | Unassigned | |
33/tcp, udp | dsp | Display Support Protocol |
34/tcp, udp | Unassigned | |
35/tcp, udp | Any private printer server | |
36/tcp, udp | Unassigned | |
37/tcp, udp | time | Time; alias = timeserver |
38/tcp, udp | Unassigned | |
39/tcp, udp | rlp | Resource Location Protocol; alias = resource |
40/tcp, udp | Unassigned | |
41/tcp, udp | graphics | Graphics |
42/tcp, udp | nameserver | Host Name Server; alias = nameserver |
43/tcp, udp | nicname | Who Is; alias = nicname |
44/tcp, udp | mpm-flags | MPM FLAGS Protocol |
45/tcp, udp | mpm | Message Processing Module |
46/tcp, udp | mpm-snd | MPM (default send) |
47/tcp, udp | ni-ftp | NI FTP |
48/tcp, udp | Unassigned | |
49/tcp, udp | login | Login Host Protocol |
50/tcp, udp | re-mail-ck | Remote Mail Checking Protocol |
51/tcp, udp | la-maint | IMP Logical Address Maintenance |
52/tcp, udp | xns-time | XNS Time Protocol |
53/tcp, udp | domain | Domain Name Server |
54/tcp, udp | xns-ch | XNS Clearinghouse |
55/tcp, udp | isi-gl | ISI Graphics Language |
56/tcp, udp | xns-auth | XNS Authentication |
57/tcp, udp | Any private terminal access | |
58/tcp, udp | xns-mail | XNS Mail |
59/tcp, udp | Any private file service | |
60/tcp, udp | Unassigned | |
61/tcp, udp | ni-mail | NI MAIL |
62/tcp, udp | acas | ACA Services |
63/tcp, udp | via-ftp | VIA Systems - FTP |
64/tcp, udp | covia | Communications Integrator (CI) |
65/tcp, udp | tacacs-ds | TACACS-Database Service |
66/tcp, udp | sql*net | Oracle SQL*NET |
67/tcp, udp | bootpc | DHCP/BOOTP Protocol Server |
68/tcp, udp | bootpc | DHCP/BOOTP Protocol Server |
69/tcp, udp | tftp | Trivial File Transfer |
70/tcp, udp | gopher | Gopher |
71/tcp, udp | netrjs-1 | Remote Job Service |
72/tcp, udp | netrjs-2 | Remote Job Service |
73/tcp, udp | netrjs-3 | Remote Job Service |
74/tcp, udp | netrjs-4 | Remote Job Service |
75/udp | Any private dial-out service | |
76/tcp, udp | Unassigned | |
77/tcp, udp | Any private RJE service | |
78/tcp, udp | vettcp | Vettcp |
79/tcp, udp | finger | Finger |
80/tcp, udp | www | World Wide Web HTTP |
81/tcp, udp | hosts2-ns | HOSTS2 Name Server |
82/tcp, udp | xfer | XFER Utility |
83/tcp, udp | mit-ml-dev | MIT ML Device |
84/tcp, udp | ctf | Common Trace Facility |
85/tcp, udp | mit-ml-dev | MIT ML Device |
86/tcp, udp | mfcobol | Micro Focus Cobol |
87/tcp, udp | Any private terminal link; alias = ttylink | |
88/tcp, udp | kerberos | Kerberos |
89/tcp, udp | su-mit-tg | SU/MIT Telnet Gateway |
90/tcp, udp | DNSIX Security Attribute Token Map | |
91/tcp, udp | mit-dov | MIT Dover Spooler |
92/tcp, udp | npp | Network Printing Protocol |
93/tcp, udp | dcp | Device Control Protocol |
94/tcp, udp | objcall | Tivoli Object Dispatcher |
95/tcp, udp | supdup | SUPDUP |
96/tcp, udp | dixie | DIXIE Protocol Specification |
97/tcp, udp | swift-rvf | Swift Remote Virtual File Protocol |
98/tcp, udp | tacnews | TAC News |
99/tcp, udp | metagram | Metagram Relay |
100/tcp | newacct | (unauthorized use) |
101/tcp, udp | hostname | NIC Host Name Server; alias = hostname |
102/tcp, udp | iso-tsap | ISO-TSAP |
103/tcp, udp | gppitnp | Genesis Point-to-Point Trans Net; alias = webster |
104/tcp, udp | acr-nema | ACR-NEMA Digital Imag. & Comm. 300 |
105/tcp, udp | csnet-ns | Mailbox Name Nameserver |
106/tcp, udp | 3com-tsmux | 3COM-TSMUX |
107/tcp, udp | rtelnet | Remote Telnet Service |
108/tcp, udp | snagas | SNA Gateway Access Server |
109/tcp, udp | pop2 | Post Office Protocol version 2 (POP2); alias = postoffice |
110/tcp, udp | pop3 | Post Office Protocol version 3 (POP3); alias = postoffice |
111/tcp, udp | sunrpc | SUN Remote Procedure Call |
112/tcp, udp | mcidas | McIDAS Data Transmission Protocol |
113/tcp, udp | auth | Authentication Service; alias = authentication |
114/tcp, udp | audionews | Audio News Multicast |
115/tcp, udp | sftp | Simple File Transfer Protocol |
116/tcp, udp | ansanotify | ANSA REX Notify |
117/tcp, udp | uucp-path | UUCP Path Service |
118/tcp, udp | sqlserv | SQL Services |
119/tcp, udp | nntp | Network News Transfer Protocol (NNTP); alias = usenet |
120/tcp, udp | cfdptkt | CFDPTKT |
121/tcp, udp | erpc | Encore Expedited Remote Pro. Call |
122/tcp, udp | smakynet | SMAKYNET |
123/tcp, udp | ntp | Network Time Protocol; alias = ntpd ntp |
124/tcp, udp | ansatrader | ANSA REX Trader |
125/tcp, udp | locus-map | Locus PC-Interface Net Map Server |
126/tcp, udp | unitary | Unisys Unitary Login |
127/tcp, udp | locus-con | Locus PC-Interface Conn Server |
128/tcp, udp | gss-xlicen | GSS X License Verification |
129/tcp, udp | pwdgen | Password Generator Protocol |
130/tcp, udp | cisco-fna | Cisco FNATIVE |
131/tcp, udp | cisco-tna | Cisco TNATIVE |
132/tcp, udp | cisco-sys | Cisco SYSMAINT |
133/tcp, udp | statsrv | Statistics Service |
134/tcp, udp | ingres-net | INGRES-NET Service |
135/tcp, udp | loc-srv | Location Service |
136/tcp, udp | profile | PROFILE Naming System |
137/tcp, udp | netbios-ns | NetBIOS Name Service |
138/tcp, udp | netbios-dgm | NetBIOS Datagram Service |
139/tcp, udp | netbios-ssn | NetBIOS Session Service |
140/tcp, udp | emfis-data | EMFIS Data Service |
141/tcp, udp | emfis-cntl | EMFIS Control Service |
142/tcp, udp | bl-idm | Britton-Lee IDM |
143/tcp, udp | imap2 | Interim Mail Access Protocol v2 |
144/tcp, udp | news | NewS; alias = news |
145/tcp, udp | uaac | UAAC Protocol |
146/tcp, udp | iso-ip0 | ISO-IP0 |
147/tcp, udp | iso-ip | ISO-IP |
148/tcp, udp | cronus | CRONUS-SUPPORT |
149/tcp, udp | aed-512 | AED 512 Emulation Service |
150/tcp, udp | sql-net | SQL-NET |
151/tcp, udp | hems | HEMS |
152/tcp, udp | bftp | Background File Transfer Program |
153/tcp, udp | sgmp | SGMP; alias = sgmp |
154/tcp, udp | netsc-prod | Netscape |
155/tcp, udp | netsc-dev | Netscape |
156/tcp, udp | sqlsrv | SQL Service |
157/tcp, udp | knet-cmp | KNET/VM Command/Message Protocol |
158/tcp, udp | pcmail-srv | PCMail Server; alias = repository |
159/tcp, udp | nss-routing | NSS-Routing |
160/tcp, udp | sgmp-traps | SGMP-TRAPS |
161/tcp, udp | snmp | SNMP; alias = snmp |
162/tcp, udp | snmptrap | SNMPTRAP |
163/tcp, udp | cmip-man | CMIP/TCP Manager |
164/tcp, udp | cmip-agent | CMIP/TCP Agent |
165/tcp, udp | xns-courier | Xerox |
166/tcp, udp | s-net | Sirius Systems |
167/tcp, udp | namp | NAMP |
168/tcp, udp | rsvd | RSVD |
169/tcp, udp | send | SEND |
170/tcp, udp | print-srv | Network PostScript |
171/tcp, udp | multiplex | Network Innovations Multiplex |
172/tcp, udp | cl/1 | Network Innovations CL/1 |
173/tcp, udp | xyplex-mux | Xyplex |
174/tcp, udp | mailq | MAILQ |
175/tcp, udp | vmnet | VMNET |
176/tcp, udp | genrad-mux | GENRAD-MUX |
177/tcp, udp | xdmcp | X Display Manager Control Protocol |
178/tcp, udp | nextstep | NextStep Window Server |
179/tcp, udp | bgp | Border Gateway Protocol (BGP) |
180/tcp, udp | ris | Intergraph |
181/tcp, udp | unify | Unify |
182/tcp, udp | audit | Unisys Audit SITP |
183/tcp, udp | ocbinder | OCBinder |
184/tcp, udp | ocserver | OCServer |
185/tcp, udp | remote-kis | Remote-KIS |
186/tcp, udp | kis | KIS Protocol |
187/tcp, udp | aci | Application Communication Interface |
188/tcp, udp | mumps | Plus Five's MUMPS |
189/tcp, udp | qft | Queued File Transport |
190/tcp, udp | gacp | Gateway Access Control Protocol |
191/tcp, udp | prospero | Prospero |
192/tcp, udp | osu-nms | OSU Network Monitoring System |
193/tcp, udp | srmp | Spider Remote Monitoring Protocol |
194/tcp, udp | irc | Internet Relay Chat (IRC) Protocol |
195/tcp, udp | dn6-nlm-aud | DNSIX Network Level Module Audit |
196/tcp, udp | dn6-smm- red | DNSIX Session Mgt Module Audit Redir |
197/tcp, udp | dls | Directory Location Service |
198/tcp, udp | dls-mon | Directory Location Service Monitor |
199/tcp, udp | smux | SMUX |
200/tcp, udp | src | IBM System Resource Controller |
201/tcp, udp | at-rtmp | AppleTalk Routing Maintenance |
202/tcp, udp | at-nbp | AppleTalk Name Binding |
203/tcp, udp | at-3 | AppleTalk Unused |
204/tcp, udp | at-echo | AppleTalk Echo |
205/tcp, udp | at-5 | AppleTalk Unused |
206/tcp, udp | at-zis | AppleTalk Zone Information |
207/tcp, udp | at-7 | AppleTalk Unused |
208/tcp, udp | at-8 | AppleTalk Unused |
209/tcp, udp | tam | Trivial Authenticated Mail Protocol |
210/tcp, udp | z39.50 | ANSI Z39.50 |
211/tcp, udp | 914c/g | Texas Instruments 914C/G Terminal |
212/tcp, udp | anet | ATEXSSTR |
213/tcp, udp | ipx | Internetwork Packet Exchange (IPX) |
214/tcp, udp | vmpwscs | VM PWSCS |
215/tcp, udp | softpc | Insignia Solutions |
216/tcp, udp | atls | Access Technology License Server |
217/tcp, udp | dbase | dBASE UNIX |
218/tcp, udp | mpp | Netix Message Posting Protocol |
219/tcp, udp | uarps | Unisys ARPs |
220/tcp, udp | imap3 | Interactive Mail Access Protocol v3 |
221/tcp, udp | fln-spx | Berkeley rlogind with SPX auth |
222/tcp, udp | fsh-spx | Berkeley rshd with SPX auth |
223/tcp, udp | cdc | Certificate Distribution Center |
224-241 | Reserved | |
243/tcp, udp | sur-meas | Survey Measurement |
245/tcp, udp | link | LINK |
246/tcp, udp | dsp3270 | Display Systems Protocol |
247-255 | Reserved | |
345/tcp, udp | pawserv | Perf Analysis Workbench |
346/tcp, udp | zserv | Zebra server |
347/tcp, udp | fatserv | Fatmen Server |
371/tcp, udp | clearcase | Clearcase |
372/tcp, udp | ulistserv | UNIX Listserv |
373/tcp, udp | legent-1 | Legent Corporation |
374/tcp, udp | legent-2 | Legent Corporation |
512/tcp | Microsoft Windows NT Server and Windows NT Workstation 4 can send LPD client print jobs from any available reserved port between 512 and 1023; see also the description for ports 721 to 731 | |
512/udp | biff | Used by the mail system to notify users of new mail received; currently receives messages only from processes on the same computer; alias = comsat |
513/tcp | login | Remote logon such as Telnet; automatic authentication performed based on privileged port numbers and distributed databases that identify "authentication domains" |
513/udp | who | Maintains databases showing who's logged on to the computers on a local net and the load average of the computer; alias = whod |
514/tcp | cmd | Like exec, but automatic authentication is performed as for logon server |
514/udp | syslog | |
515/tcp, udp | printer | Spooler; the print server LPD service listens on tcp port 515 for incoming connections; alias = spooler |
517/tcp, udp | talk | Like tenex link, but across computers; unfortunately, does not use link protocol (actually just a rendezvous port from which a TCP connection is established) |
518/tcp, udp | ntalk | |
519/tcp, udp | utime | Unixtime |
520/tcp | efs | Extended filename server |
520/udp | router | Local routing process (on site); uses variant of Xerox NS routing information protocol; alias = router routed |
525/tcp, udp | timed | Timeserver |
526/tcp, udp | tempo | Newdate |
530/tcp, udp | courier | RPC |
531/tcp | conference | Chat |
531/udp | rvd-control | MIT disk |
532/tcp, udp | netnews | Readnews |
533/tcp, udp | netwall | For emergency broadcasts |
540/tcp, udp | uucp | Uucpd |
543/tcp, udp | klogin | |
544/tcp, udp | kshell | Krcmd; alias = cmd |
550/tcp, udp | new-rwho | New-who |
555/tcp, udp | dsf | |
556/tcp, udp | remotefs | Rfs server; alias = rfs_server rfs |
560/tcp, udp | rmonitor | Rmonitord |
561/tcp, udp | monitor | |
562/tcp, udp | chshell | Chcmd |
564/tcp, udp | 9pfs | Plan 9 file service |
565/tcp, udp | whoami | Whoami |
570/tcp, udp | meter | Demon |
571/tcp, udp | meter | Udemon |
600/tcp, udp | ipcserver | Sun IPC server |
607/tcp, udp | nqs | Nqs |
666/tcp, udp | doom | Reserved for Id software |
704/tcp, udp | elcsd | Errlog copy/server daemon |
721-731/tcp | printer | In Windows NT 3.5, all TCP/IP print jobs sent from a computer running Windows NT were sourced from TCP ports 721 through 731; Windows NT 4 and Windows 2000 source LPD client print jobs from any available reserved port between 512 and 1023 |
740/tcp, udp | netcp | NETscout Control Protocol |
741/tcp, udp | netgw | NetGW |
742/tcp, udp | netrcs | Network-based Rev. Cont. Sys. |
744/tcp, udp | flexlm | Flexible License Manager |
747/tcp, udp | fujitsu-dev | Fujitsu Device Control |
748/tcp, udp | ris-cm | Russell Info Sci Calendar Manager |
749/tcp, udp | kerberos- adm | Kerberos administration |
750/tcp | rfile | Kerberos authentication; alias = kdc |
750/udp | loadav | |
751/tcp, udp | pump | Kerberos authentication |
752/tcp, udp | qrh | Kerberos password server |
753/tcp, udp | rrh | Kerberos userreg server |
754/tcp, udp | tell | Send; Kerberos slave propagation |
758/tcp, udp | nlogin | |
759/tcp, udp | con | |
760/tcp, udp | ns | |
761/tcp, udp | rxe | |
762/tcp, udp | quotad | |
763/tcp, udp | cycleserv | |
764/tcp, udp | omserv | |
765/tcp, udp | webster | |
767/tcp, udp | phonebook | Phone |
769/tcp, udp | vid | |
770/tcp, udp | cadlock | |
771/tcp, udp | rtip | |
772/tcp, udp | cycleserv2 | |
773/tcp | submit | |
773/udp | notify | |
774/tcp | rpasswd | |
774/udp | acmaint_dbd | |
775/tcp | entomb | |
775/udp | acmaint_ transd | |
776/tcp, udp | wpages | |
780/tcp, udp | wpgs | |
781/tcp, udp | hp-collector | HP performance data collector |
782/tcp, udp | hp-managed-node | HP performance data managed node |
783/tcp, udp | hp-alarm- mgr | HP performance data alarm manager |
800/tcp, udp | mdbs_ daemon | |
801/tcp, udp | device | |
888/tcp | erlogin | Logon and environment passing |
996/tcp, udp | xtreelic | XTREE License Server |
997/tcp, udp | maitrd | |
998/tcp | busboy | |
998/udp | puparp | |
999/tcp | garcon | |
999/udp | applix | Applix ac |
999/tcp, udp | puprouter | |
1000/tcp | cadlock | |
1000/udp | ock |
Notes
Registered ports are port numbers that are not controlled by IANA but that IANA registers to indicate to the Internet community which vendor applications use them. Registered ports range from 1024 through 65535 and can be used by any process or program requesting it if the operating system has not already allocated it for a specific use. Programs and processes that communicate using remote procedure calls (RPCs) often randomly select a registered port for each RPC communication session.
See Also Internet Assigned Numbers Authority (IANA) ,port ,port number ,Transmission Control Protocol (TCP) ,User Datagram Protocol (UDP)
Stands for Wired Equivalent Privacy, a data encryption scheme for securing 802.11b wireless local area networks (WLANs).
See Also Wired Equivalent Privacy (WEP)
A geographically distributed network composed of multiple local area networks (LANs) joined into a single large network using services provided by telecommunication carriers.
Overview
Wide area networks (WANs) are commonly deployed in enterprise networking environments having company offices locating in different cities, states, regions, countries, or continents. A WAN is needed wherever offices are too far apart to be connected by local area network (LAN) technologies such as Ethernet, Fast Ethernet, and Gigabit Ethernet.
A company can build a WAN in two basic ways:
Leasing WAN services such as T1 lines or frame relay from telecommunication carriers such as local exchange carriers (LECs) or inter-exchange carriers (IXCs). This is the typical approach used by most enterprises, and it usually incurs installation plus monthly usage costs paid to the carrier.
Purchase or lay their own long-haul fiber to connect remote locations. This solution is expensive to deploy but can save money in the long run by eliminating monthly leasing costs for carrier services.
Wide area network (WAN). Example of how a typical WAN is built.
Implementation
In a typical carrier-based WAN, company LANs are connected to the carrier's services using special customer services equipment (CPE) deployed at the demarc point, the point where the company's LAN ends the and the carrier's network begins. The boundary of each LAN might be a router, bridge, access server, or other form of data terminal equipment (DTE), which connects through data communication equipment (DCE) such as a modem or channel service unit/data service unit (CSU/DSU) to the termination point of the carrier's line. From the point of view of the company LANs, the carrier's network appears as a "cloud" whose structure is unimportant and whose job is simply to get data from one LAN to another. Configuration of DCE at the customer premises is typically the responsibility of the carrier, who must ensure that these devices are configured properly to be able to access carrier services.
Routers and access servers typically support several types of WAN service connections including
Circuit-switched services such as Integrated Services Digital Network (ISDN) and dial-up modem connections
Packet-switched services such as frame relay and X.25
Mainframe connections, typically using Synchronous Data Link Control (SDLC) protocol
Peer connections using Point-to-Point Protocol (PPP) and High-level Data Link Control (HDLC) protocol
When planning a WAN, companies should consider the following:
The average and peak amount of bandwidth usage anticipated
The types of traffic that will travel over WAN links
The availability of each type of WAN services from different carriers
See Also bridge , Channel Service Unit/Data Service Unit (CSU/DSU) ,data communications equipment (DCE) ,data terminal equipment (DTE) ,demarc ,frame relay ,High-level Data Link Control (HDLC) ,Integrated Services Digital Network (ISDN) ,inter-exchange carrier (IXC) ,local area network (LAN) ,local exchange carrier (LEC) ,modem ,Point-to-Point Protocol (PPP) ,router ,Synchronous Data Link Control (SDLC) ,T1 , X.25
Known as Universal Mobile Telecommunications System (UMTS) in Europe, a worldwide standard for a third-generation (3G) cellular communications system.
Overview
Wideband Code Division Multiple Access (W-CDMA) is a cellular communication technology based on existing second generation (2G) Code Division Multiple Access (CDMA) technology but offering much higher speeds. The term Wideband in W-CDMA is used because it uses wider frequency bands than regular CDMA, allowing higher throughput and enabling downward compatibility with existing Global System for Mobile Communication (GSM) systems widely used in Europe and many other parts of the world.
The UMTS standard was proposed by the European Telecommunications Standards Institute (ETSI) and has been incorporated into the International Mobile Telecommunications-2000 (IMT-2000) initiative, a 3G roadmap from the International Telecommunication Union (ITU). W-CDMA is currently being deployed in dense urban areas in Europe as an upgrade to GSM and in Japan by NTT DoCoMo and J-Phone.
Architecture
W-CDMA uses a newly licensed part of the 2-gigahertz (GHz) band of the electromagnetic spectrum, which causes some problems because this frequency band is already used in the United States for other purposes. As a result, W-CDMA may not take hold in the United States, where a competing standard called CDMA2000, based upon QUALCOMM's cdmaOne technology, is the emerging candidate for a 3G standard. W-CDMA is not fully compatible with air and network interfaces of CDMA2000 standards, as CDMA2000 uses synchronous base station transmissions with 20-millisecond frames and W-CDMA uses asynchronous base station transmissions with 10-millisecond frames. This probably means that cellular phone manufacturers will need to build phones that support both the W-CDMA and CDMA2000 standards in order to provide customers with true worldwide roaming service.
W-CDMA chipsets run at 4.096 megahertz (MHz), which provides a maximum transmission speed of 4 megabits per second (Mbps). Because of protocol overhead and other operational considerations, however, W-CDMA is likely to support a real capacity of only 1.1 Mbps and this only with stationary users. The channel bandwidth for W-CDMA is 5 MHz, much wider than the 1.25 MHz channels of CDMA2000.
For More Information
Visit the UMTS Forum at www.umts-forum.org
See Also 2G ,3G ,CDMA2000 ,Code Division Multiple Access (CDMA) ,International Mobile Telecommunications-2000 (IMT-2000)
A seal of approval from the Wireless Ethernet Compatibility Alliance (WECA) certifying that wireless networking devices such as access points and network cards are fully compliant with the 802.11b wireless networking standard.
Overview
The WiFi seal of approval guarantees 802.11b wireless devices from one vendor will interoperate with similar devices from any other wireless vendor. WECA is composed of major wireless networking vendors and software developers and its goal is to promote the 802.11 standards by ensuring interoperability between equipment from different vendors.
For More Information
Find out more about WiFi at www.wirelessethernet.org
See Also wireless networking
The original 16-bit version of Microsoft Windows that made personal computers easier to use and more productive.
Overview
This original version of Windows went through several earlier versions, but the first widely used version was Windows 3.0, which was released in 1990 and provided users with a graphical user interface (GUI) environment that was easier to learn and use than the command-line environment of Microsoft's earlier MS-DOS operating system. In 1992, Microsoft Corporation released Windows 3.1, which included additional enhancements and utilities and became widely popular with both consumers and business. Windows 3.1 is now considered a legacy operating system and has largely been replaced by Windows 98, Windows Millennium Edition (Me), and Windows XP in the consumer market and by Windows NT and Windows 2000 in the business arena.
Some of the unique features of Windows 3.1 that distinguished it from the earlier MS-DOS operating system include
A GUI that displays applications in separate windows that can be resized and arranged in any fashion
Virtual memory, a technique for swapping between RAM and disk space that increases the number of applications that can be run simultaneously
Customizable user interface elements, including the color scheme, fonts, arrangement of windows, and mouse settings
Data sharing by applications using Dynamic Data Exchange (DDE) and object linking and embedding (OLE)
TrueType fonts, which are displayed in What You See Is What You Get (WYSIWYG) fashion and can be scaled to any size
Device independence, which makes it easier for manufacturers to write device drivers for their hardware
Network-aware File Manager and Print Manager utilities, which enable access to shared network drives and printers
Windows 3.1. The graphical user interface of Windows 3.1.
Architecture
Windows 3.1 was a 16-bit cooperative multitasking graphical operating system that ran on top of MS-DOS and shared some architectural similarities with MS-DOS. Windows 3.1 used a layered architecture (see the figure) consisting of three main components:
A top-layer Windows application programming interface (API) that allows software developers to write 16-bit Windows programs without needing to understand the details of how the operating system routines work internally or how device drivers are implemented and communicate with underlying hardware.
A middle layer consisting of Windows core components and extensions. The core components make up the kernel of the operating system and consist of three subcomponents:
Krnl386.exe: Handles basic operating system tasks such as memory management, process and thread scheduling, and file input/output (I/O)
User.exe: Manages user I/O devices such as the keyboard and mouse, manages communication ports, and keeps track of Windows user interface elements such as windows, dialog boxes, icons, and menus
Gdi.exe: Manages drawing screen graphics and printing
The middle layer also includes extensions to the core operating system components that are supplied in the form of dynamic-link libraries (DLLs) that add extra functionality to the Windows environment, such as multimedia support and DDE. Windows DLLs make the Windows operating system environment extensible, allowing software manufacturers to add basic functionality to Windows by creating their own custom DLLs. Windows optimizes memory usage by dynamically loading only the DLLs that it needs at a given time.
A bottom layer, consisting of Windows drivers, that provides device drivers for different hardware devices managed by Windows, such as the keyboard, mouse, video display, and communication ports.
Windows 3.1. The architecture of Windows 3.1.
Windows 3.1 had two modes of operation:
Standard Mode: Does not use virtual memory and cannot multitask with MS-DOS applications. In Standard Mode, MS-DOS applications can run only full-screen.
386 Enhanced Mode: Requires an Intel 386 or higher processor, uses virtual memory, and supports multitasking of MS-DOS applications in separate windows. (See the diagram.) This mode includes the Virtual Machine Manager (VMM), which creates and manages separate virtual machines (VMs) running on a single CPU. Each VM functions as though it has access to and control over the entire system's resources. Windows 3.1 and all 16-bit Windows applications run in a single system VM, while each additional MS-DOS application runs in its own separate DOS VM. Virtual device drivers (VxDs) are 32-bit protected-mode DLLs that allow more than one process to share a system resource simultaneously in order to support multitasking. Windows applications are multitasked cooperatively-that is, they must be written to properly relinquish control to other applications to allow them to share system resources. Running Win.com at the MS-DOS prompt invokes the 386 Enhanced Mode system loader (Win386.exe).
Windows 3.1 stored its system and operating system configuration information in a series of text files accessed during the boot process. These included the following:
Config.sys and Autoexec.bat, which have the same function as in MS-DOS
Win.ini, which configures the Windows desktop and working environment
System.ini, which stores the Windows system configuration, including device drivers and mode settings
Other INI files such as Progman.ini, Protocol.ini, Control.ini, and Lanman.ini
See Also Microsoft Windows ,
Also called Windows for Workgroups, a version of Microsoft Windows 3.1 released in 1994 that included integrated networking components.
See Also Windows for Workgroups
Microsoft Corporation's popular desktop operating system and successor to the earlier Microsoft Windows 3.1 and Windows for Workgroups platforms.
Windows 95. The Windows 95 desktop.
Overview
Windows 95 was designed as a desktop operating system for home, office, and business use that preserves full backward compatibility with applications for legacy operating systems such as MS-DOS, Windows 3.1, and Windows for Workgroups. Windows 95 proved wildly popular with both consumers and businesses. It has since been succeeded by several later generations of consumer Windows, including Windows 98, Windows Millennium Edition (Me), and Windows XP.
Windows 95 includes the following enhanced and new features over earlier versions of Microsoft Windows:
A completely redesigned graphical user interface (GUI) with advanced features such as a configurable desktop, taskbar, Start button, and context menus
Compatibility with legacy hardware and with MS-DOS and 16-bit Windows applications
32-bit virtual device drivers (VxDs) for protected- mode management of devices and services
Preemptive multitasking kernel that multitasks Win32 and MS-DOS-based applications, replacing the cooperative multitasking approach used by Windows 3.1
Fully integrated 32-bit disk, network, and print subsystems
Integrated built-in networking software for Microsoft Networks, Novell NetWare, and Banyan Vines
Support for long filenames
Support for plug and play automatic hardware installation and configuration
Advanced Power Management (APM) support for mobile users
Integrated Windows Messaging for e-mail
Integrated dial-up networking for Internet connectivity and for Remote Access Service (RAS) connectivity
Windows 95. The Windows 95 architecture.
Integrated support for multimedia sound and video applications
Microsoft Internet Explorer, an integrated Web browser
Support for advanced features for network administrators, including hardware profiles, user profiles, and system policies
Architecture
The Windows 95 architecture evolved from Windows 3.1 and Windows for Workgroups, but in contrast to these 16-bit versions of Windows, which ran on top of MS-DOS, Windows 95 is a 32-bit operating system with a 32-bit kernel, VxDs, and an Installable File System (IFS) manager, and it does not require that MS-DOS be loaded on the computer. However, Windows 95 includes some 16-bit code and 16-bit components to ensure backward compatibility with MS-DOS, Windows 3.1, and Windows for Workgroups. Windows 95 also supports multithreaded operation and preemptive multitasking operation and manages system resources more effectively than earlier versions of Windows, allowing more and larger applications to be multitasked.
For added protection against application crashes, Windows 95 supports virtual machines (VMs). VMs in Windows 95 are similar to those implemented in Windows 3.1 except for two differences: in Windows 95, 32-bit Windows applications (Win32 apps) can run within their own protected memory address space within the system VM, and 16-bit Windows applications (Win16 apps) also run in the system VM but share their own address space (since they must be cooperatively multitasked). MS-DOS applications run in individual VMs of their own.
Another change in Windows 95 is that system configuration information that was formerly stored in boot files (Config.sys and Autoexec.bat) and INI files is stored in a database structure called the registry. The registry is the central repository for all hardware and software configuration information. Boot and INI files are still supported for backward compatibility with legacy hardware and software.
Notes
Windows 95 went through several incremental releases, each with additional features and enhancements. To determine which version of Windows 95 you are using, run the System utility in Control Panel and look at the version number on the General tab. The incremental versions are described in the table on the following page.
Version Number | Release |
4.00.950 | Original full retail version and upgrade from Windows 3.1. |
4.00.950A | Windows 95 with Service Pack 1, also called OEM Service Release 1 (OSR1). |
4.00.950B | OEM Service Release 2 (OSR2) or OEM Service Release 2.1 (OSR2.1). If "USB Supplement to OSR2" shows up as an installed program when you use the Add/Remove Programs utility in Control Panel, you have OSR2.1 installed. |
4.00.950C | OEM Service Release 2.5 (OSR2.5). |
If your 20-digit product ID number has OEM in it, you have an original equipment manufacturer (OEM) version of Windows 95 that was probably preinstalled on your computer.
See Also Microsoft Windows ,
An upgrade for Microsoft Windows 95 and earlier versions of Windows operating systems.
Overview
Windows 98 includes the following features and enhancements over Windows 95:
A Web-aware user interface that allows Web-like views of local resources and a single tool for browsing local, network, and Internet resources
Integrated Internet software including Microsoft Internet Explorer, Outlook Express, NetMeeting, Personal Web Server, FrontPad, and NetShow
Windows Update Manager for accessing the Internet to download enhancements and fixes to Windows 98
Improved networking support with a faster Transmission Control Protocol/Internet Protocol (TCP/IP) protocol stack, improved dial-up networking, and support for virtual private networking
Support for FAT32 drives and a FAT32 conversion utility
Maintenance Wizard for scheduling system maintenance utilities and other new utilities that simplify administration of computers running Windows 98, including the Microsoft System Information utility, System File Checker, Registry Checker, and Windows Scripting Host (for running administrative scripts from the desktop)
Support for DVD drives and for multiple monitors on a single computer
Support for universal serial bus (USB), FireWire (IEEE 1394), and infrared wireless connectivity based on Infrared Data Association (IrDA) standards
Support for DirectX 5 and OnNow instant-on technology
Built-in Remote Access Service (RAS) for remote dial-up clients
Hypertext Markup Language (HTML)-based online help
Improved versions of many Windows 95 tools and utilities
See Also Windows 95 ,Windows Me (Windows Millennium Edition)
A powerful 32-bit operating system family from Microsoft Corporation and the successor to the earlier Microsoft Windows NT platform.
Overview
The Windows 2000 operating system is designed as a secure, robust, and highly scalable platform for both desktop and server business applications. There are four members of the Windows 2000 family-the Professional, Server, Advanced Server, and Datacenter Server versions-and each has a place in the corporate enterprise.
Windows 2000 Professional is a powerful desktop operating system that replaces Windows NT Workstation 4. It builds on both the ease-of-use of Windows 98 and the power and reliability of Windows NT. Windows 2000 Professional includes the following features:
Wizards for simplifying system configuration and common system maintenance tasks, and time-saving improvements for the user interface, including Microsoft Internet Explorer 5, an integrated Web browser
Features for mobile users, including Advanced Configuration and Power Interface (ACPI) support for laptop power management and offline files, and Synchronization Manager for remote use of network resources
Support for 4-gigabyte (GB) RAM, two-way symmetric multiprocessing (SMP), universal serial bus (USB) and IEEE 1394 interfaces, Microsoft DirectX 7, OpenGL 1.2, video port extensions, DVD and smart card technologies
IntelliMirror client for deployment and maintenance in conjunction with Windows 2000 Server
Local data protection using the Encrypting File System (EFS)
Support for Transmission Control Protocol/Internet Protocol (TCP/IP) virtual private networking using Point-to-Point Tunneling Protocol (PPTP), Layer 2 Tunneling Protocol (L2TP), and Internet Protocol Security (IPsec)
Add-on Windows Services for UNIX components for interoperability with UNIX networking environments, including a Network File System (NFS) client and server, Telnet client and server, scripting tools, and password synchronization features
Windows 2000 Server, Standard Edition , is a comprehensive application, file, print, and Internet services platform that replaces Windows NT Server 4 and provides increased reliability, scalability, management, and applications support. Its features include the following:
Active Directory directory service, a directory service based on the X.500 directory specifications that simplifies centralized, one-point management of distributed network resources.
Windows Management Tools, which are snap- ins for the Microsoft Management Console (MMC). MMC provides a unified interface for managing enterprise-level network resources.
Enhanced Internet services, including Hypertext Transfer Protocol (HTTP), File Transfer Protocol (FTP), Simple Mail Transfer Protocol (SMTP), and Network News Transfer Protocol (NNTP) server support through Internet Information Services (IIS).
Windows Terminal Services for running terminal emulation on thin clients, replacing Windows NT Server, Terminal Server Edition.
Four-way SMP support.
Enhanced COM+ component services.
Support for Kerberos and public key infrastructure (PKI) security services.
Windows 2000 Advanced Server is a powerful server operating system that replaces Windows NT Server 4, Enterprise Edition. Windows 2000 Advanced Server is designed for enterprise-level networking environments that require high availability and scalability. Its features include all the ones in Windows 2000 Server, Standard Edition, plus the following:
Support for up to 64-GB RAM (through Intel Corporation's Physical Address Extensions) and eight-way SMP
Network-based and component-based load balancing with failover clustering
Windows 2000 Datacenter Server is the high end of the Windows 2000 Server family. It supports all the features of Windows 2000 Advanced Server plus advanced clustering and 16-way SMP, with 32-way SMP available through original equipment manufacturers (OEMs).
Windows 2000. The Windows 2000 desktop.
Architecture
The architecture of Windows 2000 is similar to that of Windows NT with a few exceptions:
The kernel is modified to include support for Terminal Services.
Kernel Mode includes two new modules: Plug and Play Manager and Power Manager.
I/O Manager includes additional drivers for Asynchronous Transfer Mode (ATM), quality of service (QoS), and other functions.
Notes
If you are a Windows NT system administrator who is moving to the more powerful and scalable Windows 2000 operating system platform, you might be confused at first by the differences between the administrative tools on the two platforms. The following table can help you get up to speed quickly on Windows 2000 system administration by highlighting some of the differences between the basic administrative tools on the Windows NT and Windows 2000 platforms. Note that there is usually no one-to-one correspondence between tools on the two platforms; what can be done with one tool on Windows NT might require several on Windows 2000, and vice versa. The tools listed in the second column are therefore not exact equivalents of those in the first column. Unless otherwise indicated, all Windows 2000 tools referred to are in the Administrative Tools program group, which can be accessed either from the Start menu or from Control Panel.
Windows NT Administrative Tool | Windows 2000 Equivalent(s) |
Administrative Wizards | Configure Your Server (Various consoles also have integrated wizards.) |
Backup | Backup (in System Tools in Accessories) |
Disk Administrator | Computer Management |
Event Viewer | Event Viewer |
License Manager | Licensing |
Network Client Administrator | No equivalent |
Performance Monitor | Performance |
Remote Access Admin | Routing and Remote Access |
Server Manager | Computer Management |
System Policy Editor | Active Directory Users and Computers Group Policy |
User Manager for Domains | Active Directory Users and Computers Active Directory Domains and Trusts Local Security Policy |
Windows NT Diagnostics | Computer Management |
See Also Microsoft Windows ,
A version of Microsoft Windows designed for a broad range of handheld and mobile products, including handheld computers, Personal Digital Assistants (PDAs), Windows terminals, smart phones, digital pagers, and industrial controllers.
Overview
Windows CE is primarily intended for handheld PCs that provide portable messaging and Internet capability and for embedded systems in which the operating system is hard-coded by a vendor into a device's ROM. Windows CE is based on a subset of the standard Win32 application programming interface (API), which means that original equipment manufacturer (OEM) developers can use all of the standard Win32 development tools to create custom-based Windows CE solutions for their Windows CE-based products. Windows CE is a component-based operating system that you can use to create "mix-and-match" operating systems that provide only the functionality needed for an embedded system, thus minimizing the memory requirements of such a system. For example, a Windows CE-based industrial sensor might contain the Windows CE kernel and communication modules but not the graphical user interface (GUI). Modules include the following:
Operating system kernel (32-bit, multitasking, multithreaded, executes in ROM), graphical device interface (GDI), and USER components
Device drivers, including keyboard, touch panel, notification light-emitting diode (LED), display, audio, battery, Personal Computer Memory Card International Association (PCMCIA), serial devices, and file allocation table (FAT)/FAT32 volumes
Communication components, including support for both wired and wireless local area network (LAN) connectivity, Transmission Control Protocol/ Internet Protocol (TCP/IP) with Windows Sockets, Point-to-Point Protocol (PPP), Serial Line Internet Protocol (SLIP), Infrared Data Association (IrDA) standards, and Telephony Application Programming Interface (TAPI)
Windows CE Embedded Shell support, which allows developers to create custom shells for providing a user interface for their CE devices
Win32-like registry for storing configuration information
Windows CE is implemented on a specific hardware platform using a thin layer of code between the kernel and the hardware called the OEM adaptation layer (OAL), which isolates device-specific features of hardware from the operating system kernel, enabling developers to ignore specific hardware functionality.
The current version of Windows CE, version 3, is the basis of the popular PocketPC handheld computing platform.
See Also Microsoft Windows ,Personal Digital Assistant (PDA)
Text-based commands that can be issued at the command prompt of Microsoft Windows NT, Windows 2000, Windows XP, or Windows .NET Server for performing administrative and housekeeping tasks.
Overview
Most Windows services are managed using graphical user interface (GUI)-based administrative tools, but you can also perform many administrative tasks at the command prompt either by issuing Windows commands interactively in real time or by saving a series of commands in a text file and running them as a batch file. Windows commands are grouped into several categories:
Common Windows commands: Include commands for performing routing administration tasks. Some of the more frequently used commands are listed in the first table below.
Net commands: For starting, stopping, and configuring networking services.
TCP/IP commands: Commands associated with managing Transmission Control Protocol/Internet Protocol (TCP/IP) networking. These frequently used commands are listed in the second table in this article.
MS-DOS configuration commands: For configuring an MS-DOS environment to run MS-DOS applications. These commands include buffers, country, device, devichigh, dos, dosonly, driveparm, echoconfig, fcbs, files, install, lastdrive, ntcmdprompt, shell, stacks, and switches.
MS-DOS subsystem commands: For backward compatibility with MS-DOS applications. These commands include append, backup, debug, edit, edlin, exe2bin, expand, fastopen, graphics, loadfix, loadhigh, mem, nlsfunc, qbasic, setver, and share.
Batch commands: Used only within batch files for automating system tasks. These commands include call, echo, endlocal, for, goto, if, pause, rem, setlocal, and shift.
Filter commands: For sorting, viewing, and selecting portions of a command's output. These commands include find, more, and sort.
Redirection symbols: For redirecting the input or output of a command to something other than standard input or output. These symbols include >, <, >>, and |.
Conditional processing symbols: Allow you to issue multiple commands from the same command prompt and to act based on the results of the commands' execution. These symbols include &, &&, ||, ( ), and ^.
OS/2 configuration commands: For configuring the operating system environment for applications that run using the OS/2 subsystem of Windows NT. These commands include codepage, devinfo, libpath, and protshell.
The following table lists some of the most frequently used Windows and TCP/IP commands and provides a brief description of what they do.
Command | Description |
Assoc | Displays or modifies file extension associations |
At | Schedules commands and programs to run on a system at a specified time and date |
Attrib | Displays or changes file attributes |
Cacls | Displays or modifies the access control lists (ACLs) of files |
Chdir (Cd) | Displays the name of the current directory or changes the current directory |
Chkdsk | Displays a disk status report and corrects errors on the disk |
Cls | Clears the screen |
Cmd | Starts a new instance of the Windows command interpreter |
Compact | Displays and alters the compression of files or directories |
Convert | Converts file allocation table (FAT) volumes to NTFS file system (NTFS) |
Copy | Copies one or more files to another location |
Date | Displays the date or allows you to change the date |
Del (Erase) | Deletes specified files |
Dir | Displays a list of a directory's files and subdirectories |
Diskcopy | Copies a floppy disk |
Diskperf | Starts and stops system disk performance counters |
Doskey | Calls the doskey program, which recalls Windows commands, edits command lines, and creates macros |
Exit | Quits the command interpreter and returns to the program that started it |
Format | Formats a disk to accept Windows NT files |
Help | Provides online information about Windows NT commands |
Mkdir (Md) | Creates a directory or subdirectory |
Move | Moves one or more files to a specified directory |
Ntbooks | Accesses online Windows NT manuals |
Prompt | Changes the Windows NT command prompt |
Rename (Ren) | Changes the name of a file or files |
Rmdir (Rd) | Deletes (removes) a directory |
Start | Opens a separate window to run a program or a command |
Time | Displays the system time or sets the computer's internal clock |
Tree | Displays the directory structure of a path or disk |
Type | Displays the contents of a text file |
Ver | Displays the Windows NT version number |
Vol | Displays the disk volume label and serial number |
Winnt | Performs an installation or upgrade of Windows NT 4 |
Winnt32 | Performs an installation or upgrade of Windows NT 4 |
Xcopy | Copies files and directories, including subdirectories |
Command | Description |
Arp | Displays or modifies the IP-to-MAC address translation tables |
Finger | Displays user information on a system running the finger service |
Ftp | Transfers files to or from a File Transfer Protocol (FTP) server |
Hostname | Prints the name of the current computer (host) |
Ipconfig | Displays current TCP/IP network configuration values |
Lpq | Obtains status of a print queue of a Line Printer Daemon (LPD) server |
Lpr | Prints a file to an LPD server |
Nbtstat | Displays protocol statistics and current NetBIOS over TCP/IP (NBT) connections |
Netstat | Displays TCP/IP protocol statistics and connections |
Nslookup | Displays information from Domain Name System (DNS) name servers |
Ping | Verifies connections to a remote computer |
Rcp | Copies files to or from a system running rshd |
Rexec | Runs commands on remote computers running rexec |
Route | Displays or modifies network routing tables |
Rsh | Runs commands on remote computers running rsh |
Tftp | Transfers files to or from a system running tftp |
Tracert | Displays the route taken to a remote host on an internetwork |
See Also command ,command interpreter ,command line ,command prompt ,Net commands
An application development framework from Microsoft Corporation.
Overview
Windows Distributed interNet Applications Architecture (Windows DNA) is a programming architecture for rapidly and easily developing highly scalable networked applications that can be accessed from a wide variety of clients including traditional desktop "fat" clients, standard Web browsers, and Internet appliances. Windows DNA is based on Microsoft's "digital nervous system" paradigm for connecting applications, data sources, Web services, and users in new and dynamic ways. Windows DNA leverages the integrated services of Microsoft Windows platforms using an enhanced version of the Component Object Model (COM) framework called COM+.
Microsoft first introduced its Windows DNA strategy in September 1997 as a framework that would both embrace the existing Win32 application programming interface (API) client/server model for application development and also extend this model to include Web services and Internet-based clients. Windows DNA is being superseded by Microsoft's newer .NET Framework.
Architecture
Windows DNA services is based on a tiered architecture as follows:
Presentation services: This is the level at which applications interact with users. Presentation services in Windows DNA include support for Hypertext Markup Language (HTML), Dynamic HTML (DHTML) scripting, and the Win32 API. The key enabler for Windows DNA at the presentation level is Internet Explorer, Microsoft's universal Web client application.
Application services: Handles the core logic of distributed applications. Services at this level include Web services running on Microsoft Internet Information Services (IIS), Microsoft Message Queuing (MSMQ) services, transaction services, and component services provided by the COM+ object model.
Data services: Provides access to data sources using ActiveX Data Objects (ADO) and OLE DB for implementing Microsoft's Universal Data Access (UDA) strategy.
System services: Include services for security, management, directory, networking, and communication provided by the Microsoft Windows 2000 operating system and other Microsoft products such as SQL Server 2000 and Exchange Server 2000.
Implementation
To use the Windows DNA paradigm for distributed application development, you can take the following approach:
Separate your application into three logical tiers-presentation, business logic, and data.
Select the Windows components and technologies for your presentation level that provide your client with a suitable interface.
Write COM components to implement your business logic using the application services of Windows 2000 or Windows NT.
Use ADO to access data and use OLE DB to expose data for your third tier.
See Also ActiveX Data Objects (ADO) ,application programming interface (API) ,COM+ ,Dynamic HTML (DHTML) ,Hypertext Markup Language (HTML) ,Internet Information Services (IIS) ,.NET Framework ,OLE DB ,scripting ,Universal Data Access (UDA)
Stands for Windows Distributed interNet Applications Architecture, an application development framework based on the Microsoft Windows 2000 operating system platform.
See Also Windows Distributed interNet Applications Architecture (Windows DNA)
The primary tool for accessing file systems in 32-bit Microsoft Windows platforms.
Overview
You can use Windows Explorer to perform tasks such as
Create, move, copy, open, edit, and delete files or folders
Search for files using complex queries
Map and disconnect network drives to shared folders on network servers
View and manipulate properties of files and other file system objects
Share folders and printers for use on the network
Configure NTFS file system (NTFS) permissions, auditing, and ownership (only in Windows NT, Windows 2000, Windows XP, and Windows .NET Server)
Windows Explorer displays a hierarchical window- based view of file system and network resources in two panes. The left pane shows a hierarchical view of all available file system resources, including the desktop, local drives, mapped network drives, printers, and My Network Places. In Windows 2000, the left pane can also show search tools or a history of recently accessed resources. The right pane shows the files and folders or other objects within the currently selected drive or folder in the left pane.
Windows Explorer. The graphical user interface (GUI) of Windows Explorer.
See Also file system ,My Computer ,My Network Places
A version of Microsoft Windows 3.1 released in 1994 that included integrated networking components.
Overview
Windows for Workgroups used the same graphical user interface (GUI) as Windows 3.1 but included the following enhancements and new features:
Integrated networking including support for the NetBIOS Enhanced User Interface (NetBEUI) and Internetwork Packet Exchange/Sequenced Packet Exchange (IPX/SPX) network protocols
Add-on support for Transmission Control Protocol/Internet Protocol (TCP/IP) including Dynamic Host Configuration Protocol (DHCP), Telnet, and File Transfer Protocol (FTP) through the Microsoft TCP/IP-32 for Windows for Workgroups add-on
Improved performance with 32-bit networking software that provides support for the Network Driver Interface Specification (NDIS) 3 standard, plus backward compatibility with the NDIS 2 standard of the 16-bit Windows 3.1 operating system
Password-protected logon
Low 4-kilobyte (KB) footprint in conventional memory for use with 32-bit network drivers, enabling large MS-DOS applications to be multitasked in a Windows environment
Compatibility with Microsoft Windows NT Advanced Server, Novell NetWare, and Banyan VINES
Autodetection of many network interface cards (NICs)
Integrated mail and fax software
Workgroup version of Microsoft Mail for e-mail connectivity, and the Schedule+ utility for keeping track of appointments and tasks
Additional network utilities such as Chat, Net Watcher, WinPopup, and WinMeter
The first version of Windows for Workgroups was version 3.10, but version 3.11 soon followed, adding high- performance 32-bit networking access. Windows for Workgroups quickly became the default desktop operating system for many companies until it was superseded by Windows 95.
Architecture
The architecture of Windows for Workgroups is essentially the same as that of Windows 3.1 except for the networking subsystem, which supports the newer NDIS 3 standard. Windows for Workgroups also includes enhancements to 32-bit disk access, which is implemented as two Windows virtual device drivers (VxDs): Virtual File Allocation Table (VFAT), which is a 32-bit, protected-mode replacement for the MS-DOS file allocation table (FAT) file system; and VCACHE, which replaces the MS-DOS SmartDrive disk-caching utility and improves disk input/output (I/O). The network redirector (VREDIR) is implemented as a file system driver as well. The Installable File System (IFS) manager maintains a table that identifies which type of file system device is associated with each disk volume and forwards all I/O calls to the appropriate device.
Windows for Workgroups 3.11. The architecture of Windows for Workgroups 3.11.
See Also Microsoft Windows ,
A service in Microsoft Windows NT, Windows 2000, and Windows .NET Server dynamically registering, managing, and resolving NetBIOS names.
Overview
Windows Internet Name Service (WINS) was a popular name resolution service on Windows NT networks because it provided a dynamic means of managing NetBIOS name resolution on networks. WINS provided a central location for registering and resolving the NetBIOS names of computers into their associated Internet Protocol (IP) addresses, simplifying the task of finding and accessing resources on a network.
WINS worked by requiring each NetBIOS host (computer) to register its NetBIOS name and IP address with a WINS server using a procedure called NetBIOS name registration. These NetBIOS name-to-IP address mappings were stored in a database called the WINS database and needed to be renewed periodically through NetBIOS name registration renewal messages. If the computer's IP address changed, the WINS database was automatically updated to reflect this, making WINS a totally automatic procedure for managing these mappings. And when a computer shut down, a name release occurred, removing the computer's mapping from the WINS database.
When a WINS client (that is, a computer running Windows) wanted to connect to a shared network resource, it first queried the designated WINS server by issuing a NetBIOS name query message, providing the WINS server with the NetBIOS name of the computer it wanted to connect to. The WINS server responded by checking its WINS database and returning the IP address of the desired computer to the client, enabling the client to locate and connect to the resource.
WINS replaced an earlier form of NetBIOS name resolution based on network broadcasts and had several advantages over this previous approach:
Traffic directed to WINS servers consumes less network bandwidth than broadcasts.
WINS enables the browsing of network resources across multiple domains and subnets.
The WINS database of NetBIOS name-to-IP address mappings is dynamically maintained, eliminating the need for maintaining lmhosts files on clients.
On the newer Windows 2000 and Windows .NET Server platforms, WINS has been replaced by the Domain Name System (DNS) as the primary method for name resolution and resource location. WINS is still optionally available, however, for supporting downlevel (Windows NT, Windows 98, Windows 95, and Windows for Workgroups) servers and clients on the network.
Notes
A single WINS server can support up to about 5000 clients. However, it is a good idea to always use at least two WINS servers in order to provide fault tolerance for NetBIOS name resolution. WINS servers maintain their own separate WINS databases, but they can be configured to replicate their NetBIOS name to IP address mappings by way of a process called WINS database replication.
See Also Domain Name System (DNS) ,lmhosts file ,NetBIOS ,NetBIOS name resolution
Microsoft Corporation's implementation of the Web- Based Enterprise Management (WBEM) architecture for enterprise-level network management.
Windows Management Instrumentation (WMI). The WMI architecture.
Overview
Windows Management Instrumentation (WMI) is a layer of services in 32-bit Microsoft Windows platforms that lets network management applications track, monitor, and control computers, networking devices, and applications. WMI is based on the WBEM framework developed by the Desktop Management Task Force (DMTF) and uses the Common Information Model (CIM) for describing manageable network objects. Support for WMI is built into Windows 98, Windows 2000, Windows XP, and Windows .NET Server and is available as an add-on for Windows NT 4.
Architecture
WMI has two main components:
Windows Management Service (WinMgmt.exe): This component brokers communication between WMI consumers and providers. A WMI consumer is a management application that can interact with or query managed network objects. The Windows Management Service itself consists of
CIM repository: An object repository that is used for storing information collected from WMI-manageable hardware and software. This repository is compliant with the CIM standard.
CIM Object Manager: This component collects information from WMI providers and stores it in the repository.
WMI providers: These function as intermediaries between the network object being managed and WMI. There are WMI providers for Simple Network Management Protocol (SNMP), Win32 objects, the Registry, and Service objects. For example, the Registry provider allows information to be collected from the registries of remote computers and stored in the repository. Similarly, if SNMP information needs to be collected from SNMP-manageable devices, the SNMP provider translates this information into a format suitable for WMI. WMI is also used by Microsoft Systems Management Server (SMS), and the SMS client includes WMI providers that interact with hardware on computers.
See Also Common Information Model (CIM) , network management ,Simple Network Management Protocol (SNMP) ,Systems Management Server (SMS) ,
An upgrade to the Microsoft Windows 98 operating system.
Overview
Windows Me (Windows Millennium Edition) offers many new features and enhancements to the popular Windows 98 operating system, including
Better ways to manage digital photos, movies, and music
Protection of critical system files and System Restore for rolling back your system back to a previous working state
Improved Help and Support areas
Support for existing and upcoming universal serial bus (USB) devices
Easier ways of networking your computers together
Enhancements in networking, messaging, and Internet connectivity
See Also Windows 98 ,Windows XP
An upgrade to the Microsoft Windows 98 operating system.
See Also Windows Me (Windows Millennium Edition)
The upcoming version of Microsoft Windows server operating systems that forms the basis of Microsoft Corporation's .NET Framework.
Overview
Microsoft's Windows .NET Server family will be the foundation of the next generation of Internet-enabled businesses. It includes all the features customers expect from a Windows operating system platform, including reliability, scalability, and security, plus additional features that enable businesses to experience the full functionality of the .NET Framework.
Currently, Microsoft plans to release four different editions of Windows .NET Server:
Windows .NET Standard Server: A reliable network operating system for building business solutions quickly and easily. Standard Server supports two-way symmetric multiprocessing (SMP) and up to 4 gigabytes (GB) of memory.
Windows .NET Enterprise Server: An enhanced server platform for building hosting applications, infrastructure, and Web services. Enterprise Server supports four-way SMP and up to 32 GB of memory and will also be available for Intel Corporation's 64-bit Itanium processor platform.
Windows .NET Datacenter Server: A platform for building mission-critical enterprise solutions. Datacenter Server supports 32-way SMP and up to 64 GB of memory on the Intel x86 platform and 128 GB of memory on the 64-bit Itanium platform.
Windows .NET Web Server: Optimized for the job of Web applications hosting, Web Server is easy to deploy and manage and can be used in conjunction with Microsoft's ASP.NET Web application technology and managed from a browser-based interface.
At the time of writing, Windows .NET Server is in beta 3. As a result, the information in this article is subject to change.
See Also .NET platform
Microsoft Corporation's original 32-bit business operating system family.
Overview
Microsoft Windows NT is the basis of Microsoft's BackOffice suite of server applications and provides a secure, scalable, and reliable platform for running enterprise line-of-business (LOB) applications. Windows NT was first released in 1993 in two editions, Windows NT Advanced Server (formerly called LAN Manager for Windows NT) and a client edition, Windows NT 3.1. In 1994 the platform was enhanced and released as Windows NT Server 3.5 and Windows NT Workstation 3.5, which were both soon upgraded to Windows NT 3.51. Windows NT 3.51 included innovative networking and security features such as
NTFS file system for advanced local and remote file system security
Windows NT domains, which are implemented using domain controllers for secure logons in a networking environment
Trust relationships for building enterprise-level multidomain networks
Centralized storage of user profiles to support roaming users on the network
Remote Access Service (RAS) for supporting remote users
Support for both the server and client sides of Dynamic Host Configuration Protocol (DHCP) and Windows Internet Name Service (WINS)
Support for the software implementation of redundant array of independent disks (RAID) levels 0, 1, and 5
Integrated support for the Transmission Control Protocol/Internet Protocol (TCP/IP) protocol suite and associated utilities
Support for Portable Operating System Interface for UNIX (POSIX) and Operating System/2 (OS/2) text-based applications
Services for Apple Macintosh
Support for Novell NetWare migration
In 1996 the Windows NT platform was upgraded to version 4, its final version, and included new features and enhancements such as
An easy-to-use Windows 95-style desktop interface
Administrative wizards
Integrated Internet services and tools, including Internet Information Server (IIS)
Administrative tools such as System Policy Editor, Network Monitor, and Task Manager
Support for both the server and client sides of the Domain Name System (DNS) protocol
Support for the Distributed Component Object Model (DCOM)
Improvements to the core operating system services and components
Windows NT. The Windows NT 4 user interface.
The Windows NT 4 family included four editions:
Windows NT Server 4: A fast 32-bit multitasking server operating system for networking environments. It can run as a file and print server, an application server, or an authentication and access control server (domain controller), and it can support as many concurrent connections as licenses purchased and up to 256 concurrent RAS sessions.
Windows NT Workstation 4: A fast 32-bit multitasking desktop operating system that supported 10 incoming concurrent sessions and one RAS session.
Windows NT Server 4, Enterprise Edition: Included Microsoft Cluster Server (MSCS) for two-node clustering, Windows NT Load Balancing Service (WLBS) for load balancing up to 32 servers, eight-way symmetric multiprocessing (and support for up to 32 processors from selected vendors), 4-GB Memory Tuning (4GT), and additional tools and enhancements.
Windows NT. Windows NT 4 architecture.
Windows NT Server 4, Terminal Server Edition: Included Terminal Services to present the familiar 32-bit Windows user interface on Windows terminal devices and on earlier versions of Windows desktop operating systems, including those running on legacy hardware.
Microsoft's Windows NT platform is still widely used in business and industry, but it has been superseded by Microsoft's newer and more powerful Windows 2000 platform.
Architecture
Windows NT processes run in one of two modes: user mode and kernel mode. User mode provides an execution environment for user applications as well as the various Windows NT subsystems that support them, which included:
Win32 subsystem: Supports Win32 applications. (All other subsystems depend on this subsystem.)
Security subsystem: Responsible for authentication, access control, and implementing security and audit policies.
OS/2 subsystem: Responsible for running text-based OS/2 1.x applications.
POSIX subsystem: Responsible for running POSIX-compliant UNIX applications.
Windows NT processes that run in user mode are limited to an assigned portion of the system's overall address space but can use virtual memory as needed. User mode processes run at a lower priority than kernel mode processes and have no direct access to system hardware functions. User mode processes must issue all hardware access requests to the Windows NT executive for fulfillment.
The other mode of Windows NT operation is kernel mode, used for running underlying operating system processes, which run at a higher priority than those in user mode. Kernel mode processes include
Windows NT executive services: Implemented in various modules specific to operating system functions. All managers and device drivers are implemented at this level.
Microkernel: Handles core operating system functions such as thread scheduling and interrupt handling.
Hardware abstraction layer (HAL): Makes Windows NT more portable between platforms by isolating hardware-specific differences.
See Also Microsoft Windows ,
The authentication scheme used by Microsoft Windows NT-based networks.
Overview
Windows NT Challenge/Response Authentication, also commonly known as NTLM (which stands for Windows NT LAN Manager) authentication, enables user on Windows NT networks to be securely authenticated without the transmission of actual passwords across the network.
When a client attempts to log on to a Windows NT network, the domain controller challenges the client to perform a complex mathematical calculation on the user's password. The domain controller also performs the same calculation on the user's password, obtaining the password from its Security Account Manager (SAM) database. If the two calculations agree, the client is authenticated and allowed to log on to the network and access resources.
Notes
Windows 2000 uses a different authentication scheme based on the Kerberos security protocol, but NTLM authentication is still supported for backward compatibility with Windows NT domain controllers. On Windows 2000, however, NTLM is known instead as Integrated Windows Authentication.
See Also authentication protocol ,network security ,security protocols
The directory services used by Microsoft Windows NT to locate, manage, and organize network resources.
Overview
Windows NT Directory Services (NTDS) utilizes domains, trusts, and directory synchronization to provide users of enterprise-level Windows NT networks with the following capabilities:
Single-logon capability: Users can log on anywhere in the enterprise using only one account.
Centralized administration: Administrators can manage the entire network from a single location.
Universal resource access: Users can access resources anywhere in the enterprise if they have the appropriate permissions.
To build effective enterprise-level directory services using Windows NT domains, you should consider the following factors:
The number of domains needed (the domain model used)
The number of domain controllers needed to support the number of users
The placement of backup domain controllers (BDCs) to assure efficient directory synchronization of directory services
The placement of BDCs to assure effective logon and resource authentication over slow wide area network (WAN) links
See Also domain controller , domain (DNS) ,trust ,
Also called Windows NT Challenge/Response Authentication, the authentication scheme used by Microsoft Windows NT-based networks.
See Also Windows NT Challenge/Response Authentication
A language-independent scripting environment supported by recent versions of Microsoft Windows.
Overview
Scripting is a powerful tool that administrators can use to automate the execution of complex tasks such as performing system administration, installing software components, and managing files and network resources. The original MS-DOS and Windows 3.1 platforms from Microsoft Corporation supported only limited scripting ability using the DOS batch file language. Microsoft developed the Windows Script Host (WSH) to provide the Windows platform with a more powerful scripting environment based on the Component Object Model (COM).
WSH supports any scripting language that can be implemented using COM. Although Visual Basic, Scripting Edition (VBScript) is the most popular language for writing WSH scripts, other languages that can be used include JScript, Perl, TCL, REXX, Python, and even the legacy DOS batch file language. WSH provides two separate execution environments within which scripts can run:
Wscript.exe: Runs scripts from the Windows desktop environment-for example, by double-clicking on a desktop shortcut for the script.
Cscript.exe: Runs scripts from the command-line console.
The manner in which scripts are run is configured using .wsh files, which act somewhat like the legacy INI files from the Windows 3.1 environment and enable administrators to configure settings such as how long a script should be allowed to run before being terminated. To execute the script associated with a particular .wsh file, simply double-click on the file in the Windows desktop environment or use Cscript.exe at the command-line. You can even create several different .wsh files for a single script and use these in different situations.
The original version of WSH was included in the Windows NT 4 Option Pack and was supported by Windows 98 through an optional download. WSH version 2 is included with Windows 2000 and later.
See Also batch file ,Component Object Model (COM) ,scripting
Also called Winsock, an application programming interface (API) for interprocess communication (IPC) on Microsoft Windows platforms.
Overview
Windows Sockets provides an IPC mechanism for implementing both reliable, connection-oriented two- way communication and unreliable connectionless communication between processes running on two different computers. Windows Sockets is Microsoft Corporation's implementation of the Berkeley Sockets interface developed on UNIX platforms for Transmission Control Protocol/Internet Protocol (TCP/IP) networks.
Windows Sockets is implemented as a dynamic-link library (DLL) for Windows operating systems. The current implementation of Windows Sockets on Windows platforms is version 2, which supports multicasting, multiple network protocols (including TCP/IP, NWLink, and AppleTalk), and offers better performance than the previous version 1.1. Examples of applications that use Windows Sockets include File Transfer Protocol (FTP), Telnet, Microsoft Internet Explorer, and many others.
See Also application programming interface (API) ,dynamic-link library (DLL) ,interprocess communication (IPC) ,Transmission Control Protocol/Internet Protocol (TCP/IP)
A Web site for updating Microsoft Windows platforms with new features and enhancements.
Overview
Windows Update can be thought of as an online extension of Windows that helps you keep your version of Windows up-to-date with the latest features and security enhancements. To use Windows Update, select its shortcut from the Start menu (Windows Update requires Internet connectivity to work). This action opens Microsoft Internet Explorer and takes you to the site www.windowsupdate.microsoft.com. Once you have connected to the site, ActiveX controls scan your system for outdated system files and determine which new versions of these files should be installed. These system files can include drivers, patches, help files, or new Windows components you can download to keep your computer up-to-date. Note that you must be an administrator or a member of the Administrators group to access the Product Updates section of the Windows Update Web site.
Notes
You also have the option of restoring previous versions of system files that have been changed by Windows Update.
The current desktop version of the Microsoft Windows platform.
Overview
Windows XP is the most recent Windows desktop operating system platform and is intended to be the successor to Windows 2000 Professional. Windows XP comes in two editions:
Windows XP Home Edition for consumers
Windows XP Professional for business and professional users
Windows XP is built upon an enhanced version of the Windows 2000 code base and integrates the strengths of the Windows 2000 platform (standards-based security, reliability, and manageability) with the flexibility and ease of use of the Windows 98 and Windows Millennium Edition (Me) line of products, which provide full Plug and Play (PnP) support and have an easy-to-use interface). Windows XP offers dramatically improved application response times and faster boot and resume times compared to previous versions, and it is tuned to provide users with a powerful and compelling "experience" of the Windows paradigm.
Windows XP is also the associated desktop client operating system for the upcoming Windows .NET Family of server operating systems. There is also a version of Windows XP called Windows XP Embedded that is designed for handheld and mobile devices having limited processing, memory, storage, and display capacities.
See Also Windows 2000 ,Windows .NET Server
Stands for Windows Internet Name Service, a service in Microsoft Windows NT, Windows 2000, and Windows .NET Server for dynamically registering, managing, and resolving NetBIOS names.
See Also Windows Internet Name Service (WINS)
Properly called Windows Sockets, an application programming interface (API) for interprocess communication (IPC) on Microsoft Windows platforms.
See Also Windows Sockets
A computer that enables non-WINS clients to perform NetBIOS name resolution using the Windows Internet Name Service (WINS).
Overview
A WINS client is an operating system that can register its NetBIOS name with a WINS server. All Microsoft operating systems that are network-capable are (or can be configured to be) WINS clients. An example of a non-WINS client would be a Macintosh computer or a UNIX host.
A WINS proxy agent is a proxy for (acts on behalf of) non-WINS clients to allow them to communicate with WINS servers. WINS proxy agents work by listening for NetBIOS name registration broadcasts from non- WINS clients and then forwarding these broadcasts directly to a WINS server. The WINS server then checks its WINS database to see whether the NetBIOS name received is already being used on the network. If the name is in use, the WINS server returns a negative registration response to the proxy agent, and the proxy server then forwards this response back to the non- WINS client indicating that the name is already in use on the network. If the name is still available, the WINS server registers the NetBIOS name of the non-WINS client and informs the proxy agent to tell the client that registration was successful.
Non-WINS clients typically use broadcasts to perform NetBIOS name registration and resolution and are sometimes called B-node clients. A similar process to the above occurs when a B-node client tries to perform NetBIOS name discovery.
For example, if a non-WINS or B-node client wants to register its name on the network, it broadcasts a NetBIOS name registration request. The proxy agent detects this broadcast request and forwards it directly to the WINS server, which checks its WINS database to see whether the NetBIOS name is already being used on the network. If the name is in use, the WINS server responds to the proxy agent with a negative registration response, and the proxy server forwards this response back to the B-node client indicating that the name is already in use on the network.
Notes
WINS proxy agents are needed only on those subnets that have no WINS server and have non-WINS clients that need to be able to resolve the names of NetBIOS computers on other subnets. WINS proxy agents must be WINS clients but cannot be WINS servers.
See Also B-node , NetBIOS ,NetBIOS name resolution ,
A Domain Name System (DNS) resource record that identifies a host as a Windows Internet Name Service (WINS) server.
Overview
WINS records are used in Microsoft Windows NT-based networks to enable Domain Name System (DNS) servers to refer name lookups to WINS servers. On Windows NT-based networks, WINS uses a dynamically updated database, while the DNS database is static and needs to be manually configured. DNS is thus harder to manage than WINS on Windows NT. So by configuring DNS to use WINS wherever possible, you simplify administration of name resolution on the network.
WINS records are specific to Microsoft Corporation's implementation of DNS on Windows NT and are not used with the new dynamic update of Windows 2000 or in non-Microsoft Windows networks such as those using Berkeley Internet Name Domain (BIND) running on UNIX servers.
See Also Domain Name System (DNS) ,resource record (RR)
A Microsoft Windows NT, Windows 2000, or Windows .NET Server machine running the Windows Internet Name Service (WINS).
Overview
WINS servers accept NetBIOS name registrations and queries from WINS clients and WINS proxy agents and then automatically create and maintain a database of NetBIOS name-to-Internet Protocol (IP) address mappings for clients on the network to speed up NetBIOS name resolution. Client computers periodically renew their name registrations for all its NetBIOS-enabled services to keep the WINS database fresh, and when a client is shut down properly or when a NetBIOS-related service is stopped on the host, the registered NetBIOS names for the client are released from the WINS database. In addition, WINS servers maintain their database through replication with other WINS servers. To do this, you can configure WINS servers in one of two roles:
Push partners: These WINS servers send notices to their pull partners, notifying them of a certain threshold number of changes to their WINS database. You can configure this number on the push partners by using the Windows NT administrative tool WINS Manager or the WINS console in both Windows 2000 and Windows .NET Server. The pull partners respond by requesting the changes, which the push partners then send.
Pull partners: These periodically send requests to their push partners, asking if any changes have been made to their WINS databases. You can configure the time interval for sending these requests on the pull partner. The push partners respond by sending the changes.
WINS servers play a crucial role in supporting efficient NetBIOS name resolution on a network by eliminating NetBIOS broadcasts. When one computer tries to contact another using NetBIOS over Transmission Control/Internet Protocol (TCP/IP), a NetBIOS name query request is first sent directly to a WINS server, which then returns the IP address of the target host and thus enables network communication to take place.
Notes
For fault tolerance on large networks, you should consider using a second WINS server, with WINS replication configured between the primary WINS server and secondary WINS server. One primary and one secondary WINS server are recommended for every 10,000 WINS clients on the network.
WINS servers must have static IP addresses assigned. To enable non-WINS clients to be resolved, create static mappings for them in the WINS database. To enable non-WINS clients to perform NetBIOS name resolution, use WINS proxy agents.
When you configure WINS replication, you should consider the following:
You can configure WINS servers to be both push and pull partners with other WINS servers.
WINS servers replicate only changes, not the full WINS database.
On Windows NT WINS servers, you can manually force WINS replication by clicking the Replicate Now button in WINS Manager. On Windows 2000 WINS servers, you use the Action menu in the WINS console.
Over local area network (LAN) or high-speed wide area network (WAN) links, you should configure all WINS servers as both push and pull partners to keep the WINS database up-to-date on all WINS servers. Over slow WAN links, however, you should configure WINS servers as pull partners only so that you can schedule replication when WAN traffic is light.
See Also NetBIOS name resolution ,
A data encryption scheme for securing 802.11b wireless local area networks (WLANs).
Overview
Wired Equivalent Privacy (WEP) provides Layer-2 (data-link layer) security for WLANs based on the popular 802.11b standard. To perform encryption, WEP uses a shared-key algorithm from RSA Security called RC4 Pseudo Random Number Generator (PRNG), which encrypts all data being sent and received between a wireless client and an access point (AP). Key strength for WEP encryption can be configured as either 40-bit or 128-bit, with 40-bit encryption adding approximately 10 percent overhead to 802.11b transmission.
Issues
WEP has recently been shown to be a flawed protocol that can be cracked using inexpensive off-the-shelf WLAN equipment. The problem lies in the fact that WEP integrates encryption and authentication functions so that a group of users share a common key. The Institute of Electrical and Electronics Engineers (IEEE) 802.11b working group is working on a new version of WEP that will provide stronger security.
Meanwhile, many wireless vendors are offering additional layers of security to their products, which render WEP superfluous to a degree. For example, Cisco Systems' Aironet 350 Series of products include a proprietary encryption scheme that is separated from authentication and adds support for Remote Access Dial-In User Service (RADIUS). Other vendors offer their own similar proprietary schemes for enhancing WLAN security. The problem is that WEP was intended as an industry standard, while proprietary schemes do not work with each other. For now, enterprises concerned about WLAN security are probably best off buying all their equipment from a single vendor and implementing extra layers of security on top of WEP.
See Also 802.11b , encryption ,Institute of Electrical and Electronics Engineers (IEEE) ,
A technology for implementing mobile devices with the Web.
Overview
Wireless Application Protocol (WAP) is a set of standards, protocols, and technologies designed to bring Web content to mobile handheld communication devices such as cellular phones and Personal Digital Assistants (PDAs). Such devices generally have limited data input and display features, making it difficult for users to access regular Web content written in Hypertext Markup Language (HTML). To overcome this, the WAP standards include Wireless Markup Language (WML) and WMLScript, offshoots of HTML that can be used to create content custom designed for mobile devices that have small displays and limited bandwidth.
WAP was developed by Ericsson, Motorola, Nokia, and Phone.com (acquired by Openwave Systems) based on technology originally developed in 1995 by Unwired Planet (which became Phone.com). Together these four companies formed the WAP Forum in 1997 to steer the development of WAP standards and technologies. Typical uses for WAP include accessing stock market information, performing online banking, and accessing corporate inventory and sales information.
WAP enables Web content to be delivered over cellular communication systems, which are characterized by a number of issues that make then unsuitable for accessing traditional HTML Web content over Transmission Control Protocol/Internet Protocol (TCP/IP). These issues include
Low speed: WAP is designed to deliver useful content at second-generation (2G) cellular speeds of 9.6 kilobits per second (Kbps) or less. Such limited bandwidth would make it difficult to use TCP/IP with its high protocol overhead.
High latency: Cellular communications can experience latency as high as several seconds on occasion, which could lead to time-outs if TCP/IP were used.
Unreliability: Because cell phone users sometimes go through tunnels or otherwise have their transmissions drop out, using TCP/IP would lead to excessive retransmissions.
The current WAP standard is version 1.2. Version 2 of WAP will include support for animation, color graphics, location-specific content, music downloads, streaming media, and synchronization with content stored on desktop computers.
Architecture
WAP uses a layered protocol stack loosely based on the Open Systems Interconnection (OSI) reference model. The layers of the WAP stack, starting from the bottom, are
Bearer layer: This represents the underlying cellular communications physical and data-link layers, which govern how signals are transmitted and received. WAP is designed to operate with any cellular bearer system, including Time-Division Multiple Access (TDMA), Code-Division Multiple Access (CDMA), and Global System for Mobile Communication (GSM).
Transport layer: The Wireless Datagram Protocol (WDP) operates at this level. WDP provides a consistent interface between upper layers and the various cellular bearer systems.
Security layer: The Wireless Transport Layer Security (WTLS) protocol operates at this level, providing authentication, privacy, and data integrity functions. WTLS is based on the Internet standard Transport Layer Security (TLS) protocol, which itself is based on Secure Sockets Layer (SSL).
Transaction layer: The Wireless Transaction Protocol (WTP) operates at this level, providing three types of datagram delivery services: unreliable one-way requests, reliable two-way requests, and reliable two-way request-reply transactions.
Session layer: The Wireless Session Protocol (WSP) operates at this level, providing connectionless (using WDP) and connection-oriented (using WDP and WTP) communication services. WSP also functions in a similar role to Hypertext Transfer Protocol (HTTP) in traditional Web systems.
Application layer: The Wireless Application Environment (WAE) resides at this level and includes a microbrowser that interprets and displays WML and WMLScript content for the user.
Implementation
A WAP system consists of three basic components:
WAP client: This is a WAP-enabled mobile device such as a cell phone or wireless PDA. Display on such devices may range from two lines of text to a small graphical display.
Web server: This is a standard Web server on which content that WAP clients can access resides. This content is typically formatted in WML.
WAP gateway: This acts as an intermediary between WAP clients and Web servers and fulfills three roles:
Translates requests from WAP clients into a form understandable by Web servers hosting WML content.
Translates WML content served up by Web servers into a binary format for transmission to the WAP client, which then displays the content (binary transmission is used instead of text to minimize bandwidth usage)
Performs authentication of WAP clients and encryption of WAP transmissions to ensure privacy
Wireless Application Protocol (WAP). How WAP works.
A disadvantage of WAP's gateway approach is that content providers must develop redundant versions of their Web content in WML and HTML. The emerging WAP 2 standard may solve this problem by storing content as XHTML instead, since standard PC Web browsers can translate XHTML into HTML while WAP 2 gateways can convert XHTML into WML.
Prospects
WAP has provided widely popular in Europe, thanks to its implementation by major cellular communication companies such as Ericsson and Nokia, who were involved in the development of WAP. WAP usage in Western Europe topped 7 million users in 2000, and that almost doubled in 2001. Critics have disparaged WAP as being painfully slow-in one test it took users almost two minutes just to find out what was on a certain TV channel using a WAP TV guide. In reality, WAP's limitations are really the limitations of cell phones and PDAs, with their small displays and slow wireless connections. It may be that when true third-generation (3G) cellular finally arrives with its megabit speeds, vendors will increase the display sizes on mobile devices to the point where delivering standard HTML Web pages to cell phones might succeed. If this happens, WAP will clearly be an interim technology, but one that more and more people are finding uses for every day.
Notes
The earlier Handheld Device Markup Language (HDML) was a precursor to WAP and formed the initial foundation from which WML was developed.
For More Information
Visit the WAP Forum at www.wapforum.org
See Also 2G , 3G ,bandwidth ,cellular communications ,Handheld Device Markup Language (HDML) ,Hypertext Markup Language (HTML) ,Hypertext Transfer Protocol (HTTP) ,latency ,Open Systems Interconnection (OSI) reference model , XHTML
A set of technologies used to replace traditional wired Ethernet local area networks (LANs) with wireless ones.
Overview
WLAN technologies can be used to replace or enhance traditional wired Ethernet LANs and are increasing in popularity in networking environments at many large companies. Popular WLAN technologies include
802.11b. This operates in the unlicensed 2.4 gigahertz (GHz) band and provides speeds up to 11 megabits per second (Mbps).
802.11a. This is a high-speed version of 802.11b that offers speeds up to 54 Mbps.
HiperLAN. This is a high-speed wireless technology developed by the European Telecommunications Standards Institute (ETSI) that offers speeds up to 25 Mbps (a newer version, HiperLAN/2, provides speeds up to 54 Mbps).
HomeRF. This is a low-speed frequency-hopping wireless technology (most wireless technologies now use direct sequencing instead) that offers speeds of only 1 Mbps.
See Also 802.11a , 802.11b ,HiperLAN/2 ,HomeRF ,
A language used to create content for the Wireless Application Protocol (WAP) platform.
Overview
Wireless Markup Language (WML) is a formatting language similar to Hypertext Markup Language (HTML) used on the Web. WML is implemented as an Extensible Markup Language (XML) application and is designed to produce content readable from WAP- enabled cell phones and Personal Digital Assistants (PDAs).
WML is both more and less powerful than HTML. WML lacks many of the formatting features of HTML, since these features are hard to implement on the small displays offered by mobile devices. In fact, the only styles supported by WML are emphasis, strong emphasis, boldface, italics, and underlining. WML also has limited support for tables, images, and other advanced HTML features. On the other hand, WML supports features not found in HTML, including tags for:
Organizing content into decks of cards. WAP phones display only one WML card of information at a time. Cards are organized into decks, and when a card is accessed the entire deck is downloaded and cached for speedier access.
Linking cards together to facilitate navigating through a deck.
Providing dynamic interaction between user and content based on events, input forms, and selection lines.
Examples
A simple WML "Hello World" application might look like this:
<?xml version="1.0"> <!DOCTYPE wml PUBLIC "-//WAPFORUM//DTD WML 1.1//EN" "http://www.wapforum.org/DTD/wml_1.1.xml"> <wml> <card title="WML Sample"> <p>Hello World</p> </card> </wml>
The first three lines are the XML Prolog and must appear at the start of all WML files. The <wml></wml> tags define the deck, and each card is defined by <card> </card> delimiters. The output of this application on a WAP phone would be to display the title WML Sample at the top of the screen with Hello World underneath.
WML is displayed on a WAP phone using a microbrowser, which is similar to a Web browser but adapted to devices with small displays and minimal processing power. The most popular microbrowser is that from Phone.com (acquired by Openwave Systems), who originally developed their browser for the earlier Handheld Device Markup Language (HDML). Nokia has developed its own microbrowser and has made the source code available for developers to use.
Marketplace
Some vendors have produced platforms that can transcode (translate) existing HTML content into WML for delivery to WAP devices. An example is IBM, whose WebSphere Everyplace Suite, Service Provider Edition, functions as middleware between cellular providers and Web content providers.
See Also Hypertext Markup Language (HTML) , XML
Networking that uses electromagnetic waves traveling through free space to connect stations on a network.
Overview
In the broadest sense, wireless networking is composed of all forms of network communication that use electromagnetic waves of any wavelength or frequency, which includes the following portions of the electromagnetic spectrum:
Infrared (IR) laser: Also called optical wireless, this point-to-point wireless technology ranges in frequency from about 300 gigahertz (GHz) to 200 terahertz (THz) and is used primarily in confined areas where line-of-sight communication is possible. IR cannot penetrate buildings or structures, but it can reflect off light-colored surfaces. Unfortunately, IR is absorbed by water vapor, so fog or rain can disrupt network communications.
Microwave: Ranging from 2 GHz to 40 GHz, this point-to-point wireless technology is widely used for both terrestrial and satellite communication. Microwave also suffers from signal degradation when weather conditions are poor, but not as much as IR.
Broadcast radio: Ranging from 30 megahertz (MHz) to 1 GHz, this technology can be used in both point-to-point and multipoint topologies and can travel through most buildings and structures, but it suffers from multipath interference when traveling over long distances.
When most people talk about wireless networking, they are talking about one of three things:
Fixed wireless: These are services used to connect two fixed stations, typically an office building with a service provider's access point. Fixed wireless is mainly used for metropolitan area network (MAN) communications between different locations within an urban area. Examples of fixed wireless services include Local Multipoint Distribution System (LMDS) and Multichannel Multipoint Distribution System (MMDS).
Wireless local area network (WLAN): WLAN technologies are used to replace or enhance traditional wired Ethernet local area networks (LANs) and are extremely popular in the enterprise. The most popular WLAN technology is 802.11b, which operates in the unlicensed 2.4 GHz band and provides speeds up to 11 megabits per second (Mbps). Other WLAN technologies include
HomeRF, a slower frequency-hopping wireless technology (most wireless technologies now use direct sequencing instead) offering speeds of only 1 Mbps. A wideband version of HomeRF offers speeds up to 10 Mbps, but it looks as though 802.11b has eclipsed HomeRF on the low-speed WLAN front.
802.11a, a high-speed version of 802.11b that offers speeds up to 54 Mbps. 802.11a has the most momentum at present to be the high-speed successor of 802.11b, but unfortunately it is not backward compatible with 802.11b.
HiperLAN, a high-speed wireless technology developed by the European Telecommunications Standards Institute (ETSI) and offering speeds up to 25 Mbps. HiperLAN/2 can provide speeds up to 54 Mbps. HiperLAN is a compelling alternative to 802.11a with its built-in support for quality of service (QoS) and robust performance in dispersive environments due to its implementation of orthogonal frequency division multiplexing (OFDM).
Wireless personal area network (WPAN): This is a wireless network used to connect devices that are worn or carried by users over short distances. Bluetooth is an emerging standard for WPANs that bi-directional data communications at 432.6 Kbps over distances up to 33 feet (10 meters).
The rest of this article focuses on WLAN technologies, as these are the most popular form of wireless networks used in enterprise environments.
History
Wireless networking first came to the attention of enterprise users in the mid-1990s when early proprietary products appeared offering speeds under 1 Mbps. In 1997 the Institute of Electrical and Electronics Engineers (IEEE) ratified the first WLAN standard, the 802.11 specification, which supported speeds up to 2 Mbps. In 1999 the IEEE ratified a new standard, the 802.11b High Rate specification, which brought wireless speeds up to 11 Mbps, making them comparable to Ethernet and, for the first time, an attractive alternative to traditional wired Ethernet LANs. Early 802.11b equipment from different vendors proved incompatible due to implementation differences, so the Wireless Ethernet Compatibility Alliance (WECA) was formed to promote interoperability between different vendors. WECA provides a certification called WiFi, which, if it appears on an 802.11b wireless device, virtually guarantees interoperability with devices from any other wireless vendor.
In 2000 the IEEE ratified a standard called 802.11a, which provides even faster speeds of up to 54 Mbps, and access points and PC cards for this technology are now beginning to appear in the marketplace. WECA has also developed a certification for 802.11a interoperability called WiFi5 (802.11a is five times faster than 802.11b). Currently, the IEEE is developing another standard called 802.11g, which runs at 22 Mbps and is backward compatible with 802.11b. It is uncertain at present whether this new technology will succeed in the marketplace.
802.11b currently rules the market in the WLAN arena, but enterprise network architects are beginning to look at 802.11a as an option when higher speed is required. Another recent development is the move toward integrating 802.11b WLAN technology with General Packet Radio Service (GPRS), a 2.5G cellular communication technology. This integration will enable cell phones and similar devices connect to corporate WLANs to send and retrieve data, taking us one step further into a wired world.
Uses
Wireless networks are typically used for
Communication with mobile stations, which precludes the use of fixed cabling, or for mobile users such as workers moving about in large warehouses or knowledge workers at convention centers for conferences
Work areas in which it is impractical or expensive to run cabling, such as older buildings that are costly to renovate
Rapid deployment and reconfiguration of networks in companies that evolve quickly
Networking buildings together on a campus using wireless bridges or fixed wireless services from a telco
Sitting in a rubber tire in your swimming pool working on your laptop while sipping margaritas (do not try this if you value your laptop!)
Implementation
Wireless LANs (WLANs) are the simplest and most popular forms of wireless networking technology. To connect wireless stations to a traditional wired LAN, you need just two components:
Access point (AP): This is basically a bridge that has an Ethernet port and a wireless transceiver. The Ethernet port connects to the wired LAN, and the transceiver transmits signals to and receives signals from the wireless stations. The effective reception range from an access point is defined by a circular area called a cell or Basic Service Set. A typical access point might provide up to 32,290 square feet (3000 square meters) of coverage in open areas (or less when obstacles are present) and support data transmission rates of 1 to 10 Mbps. However, the number of wireless stations that an access point can effectively handle is inversely proportional to the average traffic generated by each station. In other words, wireless networks are shared networks not switched ones. When multiple access point have overlapping cells, the access points hand off communication as stations roam from one cell to another.
PC card: This is typically a card having an integrated antenna that connects the computer to the access point. There are also external devices that plug into an RJ-45 port of an Ethernet card or RS-232 serial port to provide similar connectivity. Some PC cards have an external or detachable antenna for greater distance reception. The card turns the computer in which it is installed into a wireless station on the network. The typical power output of a PC card is around 100 milliwatts (mW), which provides a coverage range of about 1000 feet (305 meters) in open areas, or less when obstacles such as walls or buildings are present.
Wireless networking. A simple wireless LAN (WLAN) in operation.
Most wireless systems use the Carrier Sense Multiple Access with Collision Avoidance (CSMA/CA) media access method, in contrast to the Carrier Sense Multiple Access with Collision Detection (CSMA/CD) method used in wired Ethernet networks. The primary reason for this is that it is difficult to detect collisions between unguided electromagnetic waves.
Marketplace
Dozens of vendors offer WLAN access points and PC cards, some of the more popular being 3Com Corporation with its AirConnect series of products, Apple Computer with its AirPort line, Enterasys Networks with its RoamAbout AP and PC card, Cisco Systems with its Aironet 340 Series Wireless products, and Agere Systems with its ORiNOCO line. Prices have fallen rapidly in the last year, and access points are now typically less than $1000 and PC cards may cost less than $200.
Issues
The biggest issue relating to wireless networking is security. Initiatives such as Wired Equivalent Privacy (WEP) from the IEEE have proven insufficient to guarantee the security of wireless networks. In addition, many products from wireless vendors are provided with security turned off by default, and if users do not enable security features their precious data will be broadcast to the world for anyone to intercept. Simply by driving around a downtown area with an 802.11b-enabled laptop, a user can often establish connections with numerous corporate wireless networks and view shared resources on these networks. As a result some wireless vendors are introducing their own proprietary solutions to ensure security for their wireless networking products.
Another issue is the susceptibility of WLANs to electromagnetic interference (EMI). For example, a microwave oven can degrade or sometimes disrupt 802.11b communication since it operates in the same microwave portion of the electromagnetic spectrum. Wireless networks also can have their speed limited by obstacles such as iron girders in buildings, concrete walls, and other signal-absorbing obstacles.
See Also 802.11 , 802.11a ,802.11b ,access point (AP) ,Bluetooth ,Carrier Sense Multiple Access with Collision Avoidance (CSMA/CA) ,Carrier Sense Multiple Access with Collision Detection (CSMA/CD) ,electromagnetic interference (EMI) ,General Packet Radio Service (GPRS) ,HiperLAN/2 ,HomeRF ,Institute of Electrical and Electronics Engineers (IEEE) ,Local Multipoint Distribution Service (LMDS) ,Multipoint Multichannel Distribution Service (MMDS) ,Orthogonal Frequency Division Multiplexing (OFDM) ,quality of service (QoS) ,
A room on the floor of a building that contains hubs, switches, and other network components for that floor.
Overview
Also called an equipment room or server room (and various other names), wiring closets generally serve networks on individual floors of a building and are connected using vertical backbone cabling running down the elevator shaft to the main equipment room, which is usually in the basement. The wiring closet on each floor is the termination point for horizontal cabling running from wall plates in work areas on the floor. This horizontal wiring typically terminates in a series of patch panels in the wiring closet. Patch cables are used to connect jacks on the patch panels to ports on hubs and switches to establish network connectivity between computers on the floor and with other floors. In a single-floor building, the wiring closet and the main equipment room are the same and are sometimes called the telecommunications closet because telecommunications services typically terminate in that room as well.
Notes
The standards of the Electronic Industries Association/Telecommunications Industry Association (EIA/TIA) recommend one wiring closet per floor, with a minimum size of 9.8 feet by 6.6 feet (3 meters by 2 meters) per 4898 square feet (455 square meters) of floor space. When stations must be located more than 300 feet (91 meters) from the wiring closet, additional wiring closets are recommended. Wiring closets should be well lit and have an adequate power supply. Equipment should be mounted on racks for greater security and efficiency. "Spaghetti" should be minimized-keep everything accurately labeled to save yourself hours of troubleshooting time when things go wrong. Keep access to the wiring closet clear and secure, and include fire protection devices.
See Also infrastructure , premise cabling ,structured wiring ,
Stands for wireless local area network, a set of technologies used to replace traditional wired Ethernet local area networks (LANs) with wireless ones.
See Also wireless local area network (WLAN)
Stands for Windows Management Instrumentation, Microsoft Corporation's implementation of the Web- Based Enterprise Management (WBEM) architecture for enterprise-level network management.
See Also Windows Management Instrumentation (WMI)
Stands for Wireless Markup Language, a language used to create content for the Wireless Application Protocol (WAP) platform.
See Also Wireless Markup Language (WML)
A logical grouping of networked peer computers that can share resources with one another.
Overview
Workgroups are usually established to share resources, including files, printers, and other devices. A workgroup is sometimes called a peer-to-peer network because all computers in a workgroup are equally important. In other words, no single computer "runs the network," as in a domain-based model.
Each computer in a workgroup handles security separately using its own local security database, which tracks who can log on to the computer and what rights or permissions users have to resources on the computer. A user who wants to log on to a computer must have an account in that computer's local security database. A user with an account on one computer does not necessarily have any permissions or rights to resources on other computers.
If a computer in a workgroup is used to provide file, print, or other resources to other computers in the workgroup, that computer is generally called a peer server or a stand-alone server. Because security is local to each computer in a workgroup, a peer server can share resources using share-level security only, which uses passwords to protect access to each resource. Users who know this password can access the resources at the level of access with which it is shared (such as read- only access or full access).
Workgroups are simple to implement but hard to maintain. Administrators must create accounts on each computer for the users who need access to them. As a result, workgroups are generally used for small networks of 10 or fewer computers in which security and centralized administration are not an issue.
See Also domain (DNS) ,server-based network
The popular Internet service that is rapidly changing the way we live and work.
Overview
The World Wide Web Consortium (W3C) defines the World Wide Web (WWW, or Web) as "the universe of network-accessible information, the embodiment of human knowledge." The WWW began as a project for sharing hypertext information over a network that was developed by Tim Berners-Lee at CERN (Conseil Europ en pour la Recherche Nucleaire), a physics research center in Geneva, Switzerland.
The Web consists of Web sites hosted on Web servers around the world and connected to the Internet. Users access the Web using Web browsers and similar client applications that use the Web's client/server protocol called Hypertext Transfer Protocol (HTTP). Web sites range from collections of text files formatted with Hypertext Markup Language (HTML) and their associated image, sound, multimedia, and script files to dynamic Web applications that can perform virtually every function imaginable. Individual HTML files within a Web site are called Web pages, and pages can be linked to other pages in the same or different sites, which explains why the word "web" is used, since this conjures up pictures of spider webs.
The Web contains a vast amount of information that is growing exponentially. Of all the interesting things that one could say about the Web (it would take a million books to exhaust the subject), we will focus on one interesting study done by IBM in 2000 that showed that "hyperspace" (another name for the Web) is actually divided into four different "regions" roughly equal in size, as follows:
Core: This comprises 30 percent of the Web and consists of highly visible public Web sites such as Yahoo! and MSN. It is possible to browse from one point in the core to any other point in the core simply by following enough hyperlinks.
Origination node: This comprises 24 percent of the Web and consists of sites that contain links that enable you to reach sites in the Core, but which cannot be traversed in the opposite direction. An example might be a personal home page with a link to MSN on it.
Termination node: This comprises another 24 percent of the Web and consists of sites that you can reach from the Core but which do not link back to the Core. In other words, these are dead-end sites and pages containing various kinds of content but usually with no hyperlinks on them.
Disconnected pages: This comprises 22 percent of the Web and consists of a number of "islands" of Web content that are completely disconnected from the Core. Broken links are often the cause of this condition.
As a result of this fascinating study, one might deduce that if you chose two Web pages at random, you have about one chance in four of being able to browse from one to the other by following links, perhaps hundreds of them! The average "link distance" between two randomly selected pages, however, was determined to be only about 16 clicks.
See Also Hypertext Markup Language (HTML) , Hypertext Transfer Protocol (HTTP) ,
A vendor-neutral organization created in 1994 that develops common, interoperable standards and protocols for the World Wide Web (WWW).
Overview
Represented by the Massachusetts Institute of Technology (MIT) in the United States and a number of international research centers, the World Wide Web Consortium (W3C) provides a variety of services to its member organizations, including the following:
Discussion groups and meetings on issues relating to the evolution of the WWW
Repositories of information, reference documents, and code relating to WWW protocols, services, and applications
The creation and testing of applications that demonstrate new types of WWW technologies
The process by which the W3C develops new standards and protocols involves four steps:
Note: An initial idea or comment is submitted as a document for discussion.
Working draft: Presents work in progress toward a possible standard by the W3C working group involved.
Proposed recommendation: Issued when a consensus has been reached within the working group.
Recommendation: Receives the director's stamp of approval as a W3C recommendation.
The director of the W3C is Tim Berners-Lee, the creator of the WWW. Membership in the W3C is tailored to organizations, but private individuals can also become affiliate members.
For More Information
Visit the W3C at www.w3c.org
See Also Internet , standards organizations ,
Stands for "Win16 on Win32," a component of the Microsoft Windows NT operating system that enables 16-bit Windows applications (such as those designed to run on Windows 3.1 and Windows for Workgroups 3.11) to run properly on Windows NT's 32-bit operating system.
Overview
Like MS-DOS applications, 16-bit Windows applications (Win16 applications) also run on Windows NT within the context of a Windows NT Virtual DOS Machine (NTVDM), which simulates the 16-bit environment necessary for these applications to run. However, although MS-DOS applications each require their own separate NTVDMs in which to run, Win16 applications run within a single NTVDM called WOW, which corresponds to the system process Wowexec.exe. And although NTVDMs hosting MS-DOS applications are single-threaded, WOW is a multithreaded NTVDM in which each Win16 application runs as a separate thread using the same shared address space. WOW also simulates the cooperative multitasking environment for which applications written for Windows 3.1 and Windows for Workgroups 3.11 are designed. WOW allows only one Win16 application to run at a time, blocking the threads of all other Win16 applications until the running application relinquishes control. If the Windows NT kernel needs to preempt the Win16 application (by preempting WOW), it always resumes with the same Win16 application.
WOW also handles the translation of 16-bit Windows application programming interfaces (APIs) and messages to their corresponding 32-bit APIs and messages, enabling interoperability and data sharing between 16-bit and 32-bit Windows applications on the Windows NT platform.
Windows NT also includes an option for running Win16 applications in their own separate NTVDMs, which enables Win16 applications to function as a process within Windows NT's preemptive, multitasking environment. You can run a Win16 application in a separate NTVDM by opening the Run box from the Start menu, typing the path to the Win16 executable, and selecting the Run In Separate Memory Space check box. Note that doing this can have negative effects on Win16 applications that need to share data with each other by using legacy data-sharing mechanisms such as Dynamic Data Exchange (DDE).
Stands for Windows Script Host, a language- independent scripting environment supported by recent versions of Microsoft Windows.
See Also Windows Script Host (WSH)
Stands for World Wide Web, the popular Internet service that is rapidly changing the way we live and work.
See Also World Wide Web (WWW)