Network Planning and Design

1. Identifying the applications that you intend to use: Computer networking may be required diverse environments such as Enterprise Resource Management (ERM), Internet telephony, Instant Messaging (IM), eMail and others. It is important to discuss the applications that you intend to use such as the above. These in turn are used for estimating the software, hardware, and traffic requirements.

2. Traffic Requirements: Computing traffic requirements include several factors. A few point to consider include-

• Identification and documentation of major traffic sources.

• Categorization of traffic as local, distributed, client/server, peer-to-peer, terminal/host or server/server.

• Estimation of bandwidth requirements for each application.

• Quality of Service (QoS) requirements for each application

• Reliability requirements.

3. Scalability Requirements: Scalability refers to the extent of network growth that should be supported. For corporation, scalability is a major consideration. Provision must be made to add users, applications, additional sites, and external network connections.

4. Geographical considerations: Consider the LAN and WAN links that may be required. Offices that are separated by large distance (for example one in Delhi and another in Bombay) can be linked together by a WAN (Wide Area Network) link. Similarly, building complexes with a compound can be linked by a LAN (Local Area Network) link. Typically, the LAN links are high band width (100Mbps) and WAN links are of lower bandwidth (64 Kbps - 2Mbps). Further, the LANs fall within the premises of a Company whereas WANs are typically leased and maintained by the Telecom. Hence, WANs are costly in bandwidth terms and need to be planned and designed with utmost care to minimize resource consumption.

5. Availability: The availability of a network need to be given careful consideration while designing a network. It is the amount of time a network is available to users over a period of time and is often a critical design parameter.  Availability has direct relation with amount of redundancy required. Another important factor that needs to be considered when computing availability requirements is the business loss to the Company due to unavailability of the network for a given amount of time. A right balance needs to be arrived at such that the profitability is maintained.

6. Security and Accessibility: Security and accessibility are among the important design phase steps. A security plan needs to be devised that meets the required security specifications. You must specify:

• a list of network services that will be provided such as FTP, Web, e-mail, etc.

• Who will be administering the security of these services

• How the people be trained on security policies and procedures

• Recovery plan, in case a security breach does take place.

7. Cost considerations: For LANs, the tendency is to minimize the equipment cost. That is minimizing the cable cost, minimizing the per port cost, and the labour cost. For WANs the primary goal is to maximize the usage of the bandwidth. This is because, the recurring costs for bandwidth are normally much higher than the equipment or labour cost. Therefore more weightage is given to reliable equipment, and efficient utilization of bandwidth. Some factors that influence cost are:

• Improve efficiency on WAN circuits by using features such as compression, Voice Activity Detection etc.

• Use technologies such as ATM that dynamically allocate WAN bandwidth.

• Integrate both voice and data circuits

• Optimize or eliminate under utilized circuits.