Logical and Physical Network Design
University of Phoenix Online
Network and Telecommunications Concepts II
May 11, 2005
Connecting computers together to create a network greatly increases the communication capabilities and can even save a company substantial amounts of time and money. A well thought out network design from a small home network to a large corporate intranet can be a deciding factor in the success of a network. Two important steps in the designing of a successful network are the logical designing phase and physical designing phase. The difference between the two and the importance of each are explained in the following pages. To help in the explanation of the difference between logical and physical network design I will be using a fictitious textile company and work through the two design steps.
The Difference Between
Logical and Physical Network Design
The company that will be getting the network designed for them is a textile manufacturing company. They have a small office occupying one floor of an adjacent office building to process all the information concerning the business such as inventory, sales, and payroll.
The first part of the designing process consists of collecting as much information about the company as possible. Everyone in the company is important for this part to gain an insight from every viewpoint and as many different departments as possible. Surveys will be sent out to the manufacturing employees in the plant and meetings will be scheduled to get information from the upper management.
The information gained from the employees on the manufacturing floor provided a starting point for how many computers would be needed there. They would only need a few in an employee break area for employee access to the company information they need such as emails and company updates. The maintenance department would also need a few computers to help track part inventory and to speed up the order and purchasing process. During the meetings with management, their needs will be gathered and the requirements for the system will be discussed. The meetings with management will continue until on and off as information is gathered and as problems or changes arise.
This entire information gathering is the beginning of the Logical design of the network. It will determine many different aspects of the network and form a basic starting point to make other major decisions. From this information the IP structure of the network will be decided. The IP structure is decided by the size of the network needed and is assigned a Class A, B or C address scheme. From the size of this network a Class C address scheme will be assigned and will be similar to 22.214.171.124. The three groups of numbers will be the network number and the last group will be the number of host the company assigns.
The company decided they would need 10 hosts in the manufacturing side and 30 in the office itself. With the amount of stations or host needed decided on, The management have completed the Logical Design and could start the Physical Design by finalizing the location of all the stations.
Once the locations of all the stations are finalized they need to decide on what specific type of system they will be using. This will involve deciding on the actual system specifics such as what type of physical cabling will be used and the topology of the system. "Topology in this case is just a fancy way of saying pattern. It's what a network looks like in a diagram on a sheet of paper, i.e., "from the top." "(Walters 2000)
There are several different types of network topologies including Star, Point-to-Point, Bus or Token-Ring. The most common and the one that will be used in this example is the Star topology. In this type of system all the computers are connected or wired to a central point such as a hub or switch. The central point in this case is a hub and can connect up to eight different devises. The central point where all the computers get their information are several file servers and, a department server and an extra added drive storage space. They will all be connected together with the most common type of cable, the twisted-pair. The specific category type of wire will be Category 5 twisted-pair. This will allow them the ability to expand and add on without the need to upgrade the wiring immediately.
By using this simple example I tried to show in a real life instance the difference between Logical and Physical Network Design. The Logical Design will usually be at the beginning of the project. This will be where all the brainstorming is performed and all the systems that would possibly be needed are at least reviewed to try and develop the best possible system. The specific number of computers needed will be decided upon and the location of them including the number of sites if need be.
The Physical Design will begin when the Logical Design is completed. It will involve the routing of all cabling and also include the type of cabling to use. The Physical Design is exactly what it says, the "Physical" equipment needed to connect the computers together laid out in a design. It could be thought of as a blueprint to the network and can be made to contain great detail. The topology of the system will also be included in the Physical Design. Money can be a limiting factor in the Physical Design and can influence the system greatly. Skimping in certain systems could end up costing more money in the end. To sum it all up I think of the Logical Design as being the thinking part of the design, trying to be logical in the design. The Physical Design is all the hardware and types of systems used to connect it all together and make it all work.
The Essential Guide to Networking
By E. Garrison Walters
August 01, 2000
Beginners Guide to Networking Third Edition
By Joe Habraken
June 14, 2001