Planning Network Circuits

Question

In terms of designing network circuits and devices, what is capacity planning and how is it done?  In your response, be sure to discuss current and future circuit loading, average circuit traffic, peak circuit traffic, and the turnpike effect.  How easy it is to gather circuit loading information, how accurate does it need to be and why?

Answer 1

while planning a network capacity, network circuits and devices play a vital role. There are two interrelated decisions in designing network circuits and devices.

1. Fundamental technology and protocols (Ethernet, TCP/IP etc.) 2. Capacity of each circuit.

Designing the circuit capacity means capacity planning. Following are some important aspects to be discussed in this concern.

Circuit loading: This means the amount of data transmitted on the circuit. While planning, the focus can be either on average circuit traffic or the peak circuit traffic depending on the application. For example in some applications like airlines have peak traffic on specific holidays or online banking network has peak traffic at the time of opening and closing hours of bank. So designing for the peak traffic Is ideal. The designer can estimate the traffic by calculating number of character transmitted per day. To estimate the future circuit loading you can first calculate the message volume by counting messages in a current network and then applying some estimated growth rate.

Turnpike Effect: It is an expression that means that the traffic increases much faster than originally estimated. This term comes from the early forecasting done for the interstate highways. The analogy with networking is whenever ant new network is designed, people are more likely to use it than the old slow one, because of its features. Thus the annual growth factor for network use may vary from 5 to 50 percent and in some cases may exceed 100 percent for high growth organizations.

While gathering the information for capacity planning of network devices, a good rule of thumb is 80 percent of this circuit loading information is easy to gather. The last 20 percent needed for precise estimates is extremely difficult and expensive to find. However precision is not a major concern because of the stair step nature of communication circuits and need for projecting future needs.