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Chapter 7. Networking > Networking Terminology

7.1. Networking Terminology

Understanding networking terminology is essential to making sense of the software and hardware used to assemble a network. The following terms are used throughout this chapter, as well as in just about any conversation about networking:


The capacity of a network connection to move information. If a network is capable of transferring data at 10 Mbps, and two users are simultaneously transferring large files, each will only have about 5 Mbps of bandwidth at their disposal. See “Hubs and switches,” later in this list, for limitations.


A short-range RF (radio frequency) wireless standard used to connect handheld devices and peripherals at speeds from 1 to 2 Mbps. Supported by industry heavyweights such as IBM, Intel, and Nokia, Bluetooth hasn’t taken off yet. It’s mostly shown up in mobile phones, although Bluetooth-capable GPS units, printers, mice, keyboards, and other devices that need to transmit modest amounts of data over short distances are on the market and gaining popularity. Windows XP only supports Bluetooth natively when Service Pack 2 is installed, adding a new Bluetooth Devices control panel that’s only visible once you’ve installed a Bluetooth receiver. The notable feature: a Bluetooth wizard that makes it easy to connect new devices.

Bluetooth devices often use a "passkey” to connect to your computer. This is for “handshaking” rather than security purposes, ensuring that your mouse won’t suddenly start controlling your office mate’s cursor. One security measure: Before any Bluetooth device can be connected to your PC, you must first check the “Turn discovery on” box in the Bluetooth Control Panel and then configure your Bluetooth device to be “discoverable.” Once a new device is added, it can connect to your PC at any time, even if the “Turn discovery on” box is later unchecked.

Your connections can be encrypted—if your applications and drivers provide it. Due to Bluetooth’s relatively short range, there’s not a lot that passersby can do, although hacker kids have risen to the challenge with “bluejacking,” sending secret messages to victims’ phones. You can prevent this by turning off discovery mode, ensuring that only devices you’ve specifically configured to work with your device can talk to it.


The technology upon which the vast majority of local area networks is built. A standard Ethernet connection is capable of transferring data at a maximum of 10 Mbps, and a Fast Ethernet connection can transfer data at 100 Mbps. A device capable of communicating of both speeds is typically labelled “10/100.”


A layer of protection that permits or denies network communication based on a predefined set of rules. A firewall can be used to restrict unauthorized access from intruders, close backdoors opened by viruses and other malicious applications, and eliminate wasted bandwidth by blocking certain types of network applications. Windows XP includes a rudimentary firewall feature, described in Section 7.2.5, later in this chapter.

Hubs and switches

Devices on your network to which multiple Ethernet connections (called nodes) are made. See Figure 7-1 for an example. The main difference between a hub and a switch is a matter of performance (and cost). A switch is capable of handling multiple, simultaneous, full-bandwidth connections, while the less expensive hub throttles all connections such that, for example, three simultaneous connections can only each use one third of the total bandwidth.

IP address

A set of four numbers (e.g., corresponding to a single computer or device on a TCP/IP network. No two computers on a single network can have the same IP address, but a single computer can have multiple IP addresses. Each element of the address can range from 0 to 255, providing 256^4 or nearly 4.3 billion possible combinations. Network Address Translation (NAT) is used to translate an address from one network to another. This is useful, for example, when a LAN is connected to the Internet. On the Internet, dedicated machines called nameservers are used to translate named hosts, such as http://www.microsoft.com, to their respective numerical IP addresses. See “Windows IP Configuration” and “NSLookup”, both in Chapter 4, for more information.


Local Area Network, a designation typically referring to a network contained in a single room or building.


Megabits per second, the unit of measure used to describe the speed of a network connection. Ethernet-based networks can transfer data either up to 10 Mbps or up to 100 Mbps. High-speed T1, DSL, and cable modem connections typically transfer data up to 1.5 Mbps, while the fastest analog modems communicate at a glacial 56 kbps, or 0.056 Mbps.

Since there are eight bits to a byte, you can determine the theoretical maximum data transfer rate of a connection by simply dividing by 8. For example, a 384 kbps connection transfers 384 / 8 = 48 KB of data per second, which should allow you to transfer a 1 MB file in a little more than 20 seconds. However, there is more going on than just data transfer (such as error correction), so actual performance will always be slower than the theoretical maximum.


Network Interface Card, commonly known as an Ethernet Adapter. If your computer doesn’t have built-in Ethernet, you’ll need a NIC to connect your computer to a network. For Desktops, your NIC should be a PCI card; for laptops, your NIC should be a PCMCIA (PC Card) card. Universal Serial Bus (USB) based NICs can also be used with both desktops and laptops.


A number representing the type of communication to initiate. For example, web browsers typically use port 80 to download web pages, so web servers must be “listening” at port 80. Other commonly used ports include port 25 for sending email (SMTP), port 110 for retrieving email (POP3), port 443 for accessing secure web pages, port 21 for FTP, port 23 for Telnet, port 22 for SSH, port 53 for DNS, port 119 for newsgroups, and port 6699 for peer-to-peer file sharing applications (such as Napster).


Point-to-Point Protocol, a protocol used to facilitate a TCP/IP connection over long distances. PPP is used by Windows to provide an Internet connection over ordinary phone lines using an analog modem. Some DSL and cable connections use PPPoE (PPP over Ethernet), discussed later in this chapter.


A protocol is the language, so to speak, that your computer uses to communicate with other computers on the network. These days, the TCP/IP set of protocols is the de-facto standard for local area networks, and is required for Internet connections.


Shorthand notation for the collection of protocols that includes Transmission Control Protocol (TCP), Internet Protocol (IP), User Datagram Protocol (UDP), and Internet Control Message Protocol (ICMP). TCP/IP is required for all Internet connections, and is the standard protocol for most types of modern LANs.


The physical layout of your network. See the next section, Section 7.1.1, for more information on how topology comes into play.


Wide Area Network, or a network formed by connecting computers over large distances. The Internet is an example of a WAN.

Wi-Fi (802.11x)

The current standard(s) for wireless networking. The 802.11x series isn’t one technology, but several. But when we talk about Wi-Fi connections, we usually mean 802.11b—the current worldwide standard, especially for home networks, which offers transmission speeds up to 11 Mbps. Its successor, 802.11g, boosts the maximum throughput to 54 Mbps while maintaining backward compatibility with 802.11b. (Also on the market is 802.11a, although its limited range and lack of compatibility with the “b” and “g” standards make it a poor choice for most Wi-Fi nuts.)

These standards include encryption to keep your data secure and to make sure that only authorized computers are able to connect. The most common method is WEP (Wired Equipment Privacy), although its successor WPA (Wi-Fi Protected Access), a subset of technology that will appear with the forthcoming 802.11i) offers increased security. But both protocols are fairly easy to crack and shouldn’t be used for mission-critical data.

A wireless network typically consists of a wireless router (the access point) connected to the Internet via broadband, and one or more computers that can tap into the router. (You can have a wireless network without a wireless router using “ad hoc” mode, but only between two computers at a time.) Most new laptops come with Wi-Fi support built in, although desktop PCs may require a wireless PCI card or USB adapter.

Wireless networking is easy to set up, but can be more challenging to run, and securing a wireless network can be a pain.

Fortunately, Windows XP can access any Wi-Fi connection out of the box, if you have the necessary security keys. Service Pack 1 attempted to promote security by making it harder to access unprotected networks, which proved extremely annoying. Service Pack 2 (discussed in Appendix H), warns you if a network is insecure, but otherwise lets you connect to it without quibbling. Beyond home and business use, public Wi-Fi networks or “hotspots” are showing up in airports, coffee houses, libraries, and other public places. Some of these hotspots offer free access; others charge. For hotspots near you, check out http://www.wi-fihotspotlist.com.


Another name for a peer-to-peer LAN.



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