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
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.
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.