These days it is hard to imagine a business without some sort of computer network in place. Businesses of all types and sizes use computers to automate tasks and to store vital company information, such as financial data, customer data, and inventory information.
The individual computers in most companies are interconnected to form a network. Different computers on the network perform different roles. There are file servers, database servers, email servers, Internet servers, and other servers, as well as end-user workstations. These computers communicate with one another using a set of rules called a protocol. Depending on the type of computer systems that are in use, more than one protocol may be in use on a company network.
Each of the company's physical locations (each building or campus) will have its own Local Area Network (LAN), as shown in Figure 1.1.
Figure 1.1 A Local Area Network (LAN) connects one or more computers in the same relatively small area, such as a single building, using TCP/IP in this example.
Each of these sites will probably be connected to each other, or to one central site, such as the corporate headquarters, through a Wide Area Network (WAN), as shown in Figure 1.2.
Figure 1.2 A Wide Area Network (WAN) connects multiple LANs over a large geographical area.
In addition, individual users might need to access the company network while working from home. These remote users may connect directly to one of the LANs by calling into a Remote Access Server via ordinary telephone lines, or they may connect over the Internet using a secure connection called a virtual private network (VPN). A VPN is shown in Figure 1.3.
Figure 1.3 A virtual private network (VPN) allows a remote user (or number of users) to access private corporate resources over a secure connection through the public Internet.
The whole collection of LANs, WANs, remote users, or VPNs is referred to as the company's Enterprise network. On an Enterprise network, the protocols in use and the services offered, as well as the devices that provide the network connectivity and services, are referred to as the network infrastructure. Given the way that businesses rely on the network infrastructure, designing such an infrastructure requires considerable planning to ensure success.
It is obvious to network professionals that the technical aspects of network infrastructure design require detailed planning, and it is easy for them to focus their efforts entirely on the technical considerations. Unfortunately, this approach is destined for failure, because it neglects to consider the crucial business elements that should be included in a network infrastructure design. If you don't thoroughly consider the business requirements for the network infrastructure, the design project is likely to result in a network that is either too simple to support the demands placed on it or too complex to deliver results efficiently and cost-effectively. Without proper consideration of business requirements, you can count on designing a network that is either too weak or too expensive.
This book will teach you the techniques you will need to know to effectively design Microsoft Windows 2000 network infrastructures that maximize performance and minimize Total Cost of Ownership (TCO). This chapter focuses on the business requirements that you will need to consider when creating your network infrastructure design.