Networking: A Beginner's Guide Fifth Edition- P10

Networking: A Beginner’s Guide Fifth Edition- P10:I have run into many people over the years who have gained good evenimpressive working knowledge of PCs, operating systems, applications,and common problems and solutions. Many of these people are wizards withdesktop computers.
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Networking: A Beginner’s Guide Fifth Edition- P10 Chapter 3: Understanding Networking 27 To choose the most suitable remote access solution, you’ll need to consider what the users need to do remotely, the number of users (both in total and at any given time), and how much you want to spend. See Chapter 10 for more information about remote access.Wide Area Networks You should think of a wide area network (WAN) as a sort of “metanetwork.” A WAN is simply multiple local area networks (LANs) connected together. This can be accomplished in many different ways, depending on how often the LANs need to be connected to one another, how much data capacity (bandwidth) is required, and how great the distance is between the LANs. Solutions include full-time leased telephone lines that can carry 56 Kbps of data, dedicated DS1 (T-1) lines carrying 1.544 Mbps, DS3 lines carrying 44.736 Mbps, and other forms (like private satellites) carrying even higher bandwidths. You can also create a WAN using VPNs over the Internet. Although this method usually offers inconsistent bandwidth, it’s often the least expensive. WANs are created when the users of one LAN need frequent access to the resources on another LAN. For instance, a company’s enterprise resource planning (ERP) system might be running at the company’s headquarters, but the warehouse location needs access to it to use its inventory and shipping functions. As a general rule, if you can design and build a system that doesn’t require a WAN, you’re usually better off, because WAN links are often expensive to maintain. However, the geographic and management structure of a particular company can dictate the use of a WAN.Internet and Intranet The Internet has become vital to the productivity of most businesses, and handling Internet connectivity on a network is often an important network service. Many different types of services are available over the Internet, including e-mail, the Web, and Usenet newsgroups. DEFINE-IT! xAN A myriad of terms refer to what are essentially wide area networks, all with variations on the xAN acronym scheme. Some examples include metropolitan area network (MAN), distance area network (DAN), campus area network (CAN), and even—I’m not making this up—personal area network (PAN), which was an IBM demonstration technology where two people shaking hands could exchange data through electrical signals carried on the surface of their skin. All of these different names, and others that I haven’t listed here, are a bit silly. I suggest you just stick with the two core terms: LAN and WAN.28 Networking: A Beginner’s Guide An Internet connection for a network consists of a telecommunications network connection to an ISP, using a physical connection such as a leased DSL line, an ISDN line, or a fractional or full DS1 (T-1) connection. This line comes into the building and connects to a box called a channel service unit/data service unit (CSU/DSU), which converts the data from the form carried by the local telephone company to one usable on the LAN. The CSU/DSU is connected to a router that routes data packets between the local network and the Internet. (Sometimes both the CSU/DSU and the router are built into the same device.) Internet security is provided either by filtering the packets going through the router or, more commonly, by adding a firewall system. A firewall system runs on a computer (or has a computer built into it, if it’s an appliance device) and helps you secure your network against various threats. An intranet, as its name suggests, is an internally focused network that mimics the Internet itself. For example, a company might deploy an intranet that hosts a web server, which stores documents such as employee handbooks, purchasing forms, and other information that the company publishes for internal use. Intranets can also host other Internet-type services, such as FTP servers or Usenet servers, or these services can be provided by other tools that offer the same functionality. Intranets usually are not accessible from outside the LAN (although they can be) and are just a much smaller version of the Internet that a company maintains for its own use. Understanding the technologies, services, and features of the Internet is complex. You can learn much more about some of the hardware that makes the Internet work in Chapter 6. Network Security Any time you share important and confidential information on a network, you need to carefully consider ...