Management: Selection and Validation

The selection and validation of networks (which in most cases will be LANs) is a subject which should be handled in a systematic and comprehensive way.

The first phase in this decision process is planning the system. This can be done in three steps, similar to the planning process in general.

1. Defining Objectives: define what the system is supposed to do. This should be as quantitative as possible and related to the creation, storage, transfer and processing of information. The goals must be based on the present situation, which can certainly be improved. The whole environment of the planned system should be looked at; there should be no restrictions at that point of the process. This leads to some key product goals from which more specific system requirements can be derived.
2. Describing the System: describe some options to achieve these goals. There will be no real improvement by only buying new equipment. Organizational and procedural improvements and adjustments are the basis for the implementation and operation of an effective computer network as a technological improvement.
3. Determine Communication Needs: explain how information has to be moved, what the network has to do. Network requirements have two major points: compatibility (the possiblity to connect the devices) and capacity (maximum performance of the net). Thus, the selection of a network should take into account interconnection with other networks and future growth of the network.

1. total costs must not exceed expected savings
2. the network has to meet the established requirements and to provide the needed services
3. network must be expandable with only incremental costs
4. network is reliable (total network failures are prevented)
5. network can handle equipment supplied by several vendors
6. ease of installation, maintenance, reconfiguration, interconnection
7. software availability

In the two phases of the selection process the responsible person has to take in a different point of view.

A few common arrangements exist for LANs . Out of this list the suitable configuration can be chosen, according to the planning process:

• baseband coaxial, bus topology
• twisted pair, star wiring
• broadband coaxial, bus topology
• twisted pair, ring topology
• optical fibre, ring topology