4. EL CRECIMIENTO DE LOS(AS) BEBÉS
4.5. La maldad / Ar z one
Wiring systems up on a local scale is one thing, but the real power of networking comes from being able to span long distances and share information with remote networks that are not under your control. Collaborating with suppliers or customers who might be situated on the far side of the planet is now commonplace, and to make this all possible, you’ll need to exploit the services offered by the world’s largest wide area network: the Internet.
A wide area network (WAN) is used to connect systems over a wide geographical displace- ment, acting primarily as a method of connecting distributed local area networks.
To put this in context, if you are using SBS 2003 in your business and decide to send an email to a colleague, the chances are you’ll be using the Microsoft Exchange 2003 component of SBS 2003 to do this. The email is processed on your local server, and all the network traffic is contained within your business environment. You have exploited the facilities of your LAN to send the email. If you subsequently need to send an email to a supplier who happens to have his business in Peru, your email is first passed from your LAN, out to the Internet, and then posted through many, many email relay systems until it finally reaches the end client system that knows about your supplier. Your supplier’s server is probably on its own LAN, where the supplier logs in and reads your email. In this example, the Internet is the wide area network.
A few points about WANs should be noted for the small business user: • WANs connect LANs.
• WANs are normally supplied by your telecommunications company.
• You will have no direct control over the WAN systems; you simply subscribe to the services provided by the telecommunications company.
• The most popular WAN is the Internet.
• It’s possible to hire leased lines from your telecommunications company that offer dedicated WAN connections. You can use these to connect branch offices to your headquarters.
Another kind of WAN connection is that provided by a modem. When you dial in to your SBS 2003 server to get remote network access to your LAN, you are effectively creating your own mini WAN. On a grander scale, you can use point-to-point dial-up connections to span the distance between branch offices and your headquarters.
Security can be added to connections that exploit the Internet, using technology known as virtual private networks (VPNs). These are covered in more detail later in this chapter, but for now it’s sufficient to say they provide a safe-enough medium to connect distributed LANs together, meaning every business can exploit the Internet for B2B and B2C connectivity with- out the worry of hackers easily gaining access.
To get an idea of how distributed the Internet is, have a look at The Internet Mapping Pro- ject (see Figure 2-10). Started by Bell Labs and now run by Lumeta, this project has been running since the summer of 1998. The project’s goal is to analyze the layout of the Internet over a long period of time to help with long-term trending problems of sizing and distribution. To date, their data has helped fix routing problems and helped track down the source of distributed denial of service (DDoS) attacks. For more information, see http://research.lumeta.com/ches/map/ index.html.
Figure 2-10.The Lumeta Internet mapping project
TCP/IP
You’ve heard a lot about it, but what is TCP/IP? It stands for Transmission Control Protocol/
Internet Protocol and is the industry networking standard used most widely today. Other net-
working standards also exist, but with the advent of the Internet (which is solely based on the services provided by TCP/IP) and industry giants such as Microsoft standardizing platform development on the paradigm of “Internet readiness,” then it’s little wonder that TCP/IP is removing all the competition.
The protocol itself was designed as a global player, capable of routing many diverse networks together over a number of different connection types (from slow dial-up to the staggering speeds of some of the modern SDSL connections, which can carry data up to 24 Mbps—for example, ADSL 2).
Microsoft Windows platforms rely heavily on the underlying principles of TCP/IP to cre- ate the networked environment known as the domain. Many of the services and applications you have come to rely on in the modern world, such as email and the Internet, would not be possible without TCP/IP.
The standards for TCP/IP are published as open source documents on the Internet, all in the format of ratified documents known as Requests for Comments (RFCs). These RFCs detail the workings of every underlying TCP/IP service and can be used by systems developers when they are creating new applications or operating systems that need to interoperate within a TCP/IP environment.