CompTIA A_ Certification All-In-One Exam Guide, Seventh Edition - Michael Meyers [409]
Network protocol software takes the incoming data received by the network card, keeps it organized, sends it to the application that needs it, and then takes outgoing data from the application and hands it to the NIC to be sent out over the network. All networks use some protocol. Although many protocols exist, one dominates the world of PCs—TCP/IP.
NetBEUI/NetBIOS
Before we talk about TCP/IP, we need to discuss a little history. During the 1980s, IBM developed NetBIOS Extended User Interface (NetBEUI), the default protocol for Windows for Workgroups, LANtastic, and Windows 95. NetBEUI offers small size, easy configuration, and a relatively high speed, but it can’t be used for routing. Its inability to handle routing limits NetBEUI to networks smaller than about 200 nodes.
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NOTE A node is any device that has a network connection—usually this means a PC, but other devices can be nodes. For example, many printers now connect directly to a network and can therefore be deemed nodes. I use the term node extensively in the rest of the chapter in place of PC or networked computer. This is especially true when I talk about wireless technologies, because that’s the term the manufacturers use.
You can connect multiple smaller networks into a bigger network, turning a group of LANs into one big WAN, but this raises a couple of issues with network traffic. A computer needs to be able to address a packet so that it goes to a computer within its own LAN or to a computer in another LAN in the WAN. If every computer saw every packet, the network traffic would quickly spin out of control! Plus, the machines that connect the LANs—called routers—need to be able to sort those packets and send them along to the proper LAN. This process, called routing, requires routers and a routing-capable protocol to function correctly.
NetBEUI was great for a LAN, but it lacked the extra addressing capabilities needed for a WAN. A new protocol was needed, one that could handle routing.
TCP/IP
Transmission Control Protocol/Internet Protocol (TCP/IP) was originally developed for the Internet’s progenitor, the Advanced Research Projects Agency Network (ARPANET) of the U.S. Department of Defense. In 1983, TCP/IP became the built-in protocol for the popular BSD (Berkeley Software Distribution) UNIX, and other flavors of UNIX quickly adopted it as well. TCP/IP is the best protocol for larger networks with more than 200 nodes. The biggest network of all, the Internet, uses TCP/IP as its protocol. Windows also uses TCP/IP as its default protocol.
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NOTE Novell developed the Internetwork Packet Exchange/Sequenced Packet Exchange (IPX/SPX) protocol exclusively for its NetWare products. The IPX/SPX protocol is speedy, works well with routers, and takes up relatively little RAM when loaded. Although once popular, it has all but disappeared in favor of TCP/IP. Microsoft implements a version of IPX/SPX called NWLink.
Client Software
To access data or resources across a network, Windows needs to have client software installed for every kind of server you want to access. When you install a network card and drivers, Windows installs at least one set of client software, called Client for Microsoft Networks (Figure 23-22). This client enables your machine to do the obvious: connect to a Microsoft network! Internet-based services work the same way. You need a Web client (such as Mozilla Firefox) to access a Web server. Windows PCs don’t just access shared data magically but require that client software be installed.
Figure 23-22 LAN Properties window showing Client for Microsoft Networks installed (along with other network software)
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NOTE If you right-click on the Network button in Windows Vista/7, you’re taken to the Network and Sharing