Planning is an essential part of any network installation or upgrade. Before you install or even select new hardware, you must think about issues such as hardware compatibility, business requirements, and ergonomics. This chapter examines some of the factors you should consider during the network planning stage and discusses how your decisions can affect your future actions.
This chapter requires an understanding of a network's hardware
The first step in developing a network plan is to understand the requirements of the organization that will run the network and the needs of the people who will use it. After you have determined the company's requirements and the users' needs, you can set about developing a technical configuration that satisfies those requirements and needs.
The first order of business is to determine why the organization wants a new network installed. You might be providing a network for a brand new installation that has no existing equipment, or you might be asked to network a
An organization with an existing network (or a group of computers that it wants to connect to a network) probably has some idea of what services it wants the network to provide, whereas an organization wanting a new installation might have less of an idea about what it needs. At the most basic level, businesses usually want their users to be able to access shared drives and printers and connect to the Internet. These factors alone allow the administrator to make some basic decisions. Sharing
Some organizations might have more elaborate requirements. It is also important to remember that when it comes to computers, businesspeople often know what they want but have no idea what's involved in getting it. For example, some organizations might need to maintain elaborate databases, which requires powerful servers with fast processors, a lot of memory, and large hard drives. Other companies might need to work with huge graphic images or full-motion video, which requires
In addition to talking to the heads of organizations about their network needs, it's also a good idea to
One of the most crucial elements of the site evaluation is an understanding of where the various computers and other network components must be located in relation to each other. On a typical 10Base-T or 100Base-TX Ethernet network, computers can be up to 100
Another consideration is obstacles between the computers that are to be connected to the network. This factor can determine what kind of cabling job is needed for the site. For example, if the network will consist of computers that are all located in a single room, you might be able to network them using prefabricated cables running loose around the perimeter of the room. This is a relatively simple project that requires no special equipment. However, if the network will be a large one, if the computers are located in many different rooms, or if the site requires the most professional appearance possible, you have to plan an internal cable installation. This type of installation uses bulk cable, installed into ceilings and walls, connected to a central patch panel at one end, and connected to individual wall plates at each of the computer locations. Internal installations require additional planning, more equipment, and greater expertise. They also add significantly to the cost of the job.
All network plans require an evaluation of the areas where the workstations and other client components will go, but on more elaborate network installations you must also consider where to put the back-end components, such as hubs, servers, routers, and so on. In all but the smallest installation, it is important to secure this type of equipment physically, such as in a locked room or closet, so that it's protected from damage, either accidental or malicious. It's not uncommon for expensive tower servers located in public areas to be turned into stands for potted plants or targets for refrigerator magnets, or even to disappear. Depending on the
The science of ergonomics involves more than the development of strangely shaped keyboards. Part of the job of planning a network includes selecting equipment designs that are suitable for the working environment and placing them in locations where they will provide the most utility and cause the least distraction. For example, you might be able to make one user very happy by moving the departmental laser printer off her desk and onto a printer stand in a more central location. This might mean spending a few extra dollars on an external print server device that enables you to connect the printer directly to the network cable, but if more people have more
Another factor to consider is the selection and placement of client workstations
In addition to the physical locations of the network components, you must also be aware of the physical environment in which they will run. This might seem unnecessary in an office building that maintains constant levels of temperature and humidity, but there are several important factors to consider. One of these factors is whether the comfortable climate you feel during working hours is
Consider also that the equipment closets in which you plan to locate your servers and other components might not be climate controlled. If you plan to create a data center containing a large number of computers, routers, and other heat-producing devices, you will probably need an independent climate control system to keep the room cool enough. A source of clean, consistent electrical power is also important. A data center might require its own electrical circuits to support a lot of equipment in a single location. If this is the case, you might also want to consider adding surge protection and a backup power supply for the entire installation. This could include standard uninterruptible power supply (UPS) units, or even a backup generator with a failover switch.
Of course, not every network installation is located in a comfortable office building. You might find yourself having to plan for a network that is exposed to extreme environments, such as outdoors or industrial areas that expose the equipment to abnormal amounts of heat or cold, humidity, dust, electromagnetic interference, chemical vapors, and so forth. There are a variety of products available that enable computer networks to operate in these conditions, including
If you will be performing an internal cable installation, you need to examine the places where the cables will run for possible obstructions and sources of interference. Copper-based cables are highly susceptible to electromagnetic fields caused by fluorescent light fixtures, electric motors, and other types of electrical equipment. Even seemingly
To ensure that your network is reliable, check to see that there are cable routes you can use that avoid these sources of interference. Otherwise, you might have to use cable with additional shielding, or even fiber optic cable, which is not affected by electromagnetic interference. You must also be aware of the fire and building codes in your area that
Even if you are planning to outsource the cable installation, you should be aware of conditions that can affect its cost.
After you have determined the organization's networking needs, you can start to design the network and begin selecting the products you'll need to construct it. For a brand new network, you might be responsible for the computers themselves. You must be careful to select models that can fully support the networking
Hardware compatibility is always a major issue when you're planning a network, but if you will be working with existing equipment—either an existing network or a group of stand-alone computers—compatibility becomes even more crucial. Many of the purchasing decisions you make for network equipment will be based on the protocols you choose to run,
Most Ethernet products work well together, even when they're made by different manufacturers, but you still want to be sure that the products you select all support the same type of Ethernet. For example, if you're expanding an existing network, you might want to use Fast Ethernet on the new computers and upgrade the existing computers from regular Ethernet at a later time. You might purchase dual-speed network interface cards (NICs) for the new computers, but leave the 10-Mbps NICs in the older ones. In such a case, you must purchase a dual-speed hub as well because, although a Fast Ethernet hub will support the new computers at 100 Mbps, it won't support the old computers at 10 Mbps. You can't connect a 10-Mbps hub to a 100-Mbps hub, so the old and the new computers won't be able to communicate with each other. A dual-speed hub with ports that can support either Fast Ethernet or regular Ethernet enables you to connect all of the computers to one network.
In addition to major compatibility issues like these, there are many small decisions you must make to ensure that all of the components of your network function together properly. For example, you must make sure that you purchase NICs that use the appropriate bus type for the computers and the correct connector for the network medium you've
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