Network Design Principles: 80/20 Rule

The 80/20 is also known as the Pareto Principle. It refers to the work of Vilferdo Pareto that describes the relationship between the elements that make up a whole and the influence that each element exert on the whole.

The 80/20 rule is observed in all large systems, including data networks. Although the exact percentage may vary, the rule can be observed in many situations in the design and deployment of data networks, such as:

  • 80% of traffic in the network is generated by 20% of the applications.
  • 80% of the cost of the network comes from 20% of its components.
  • 80% of the design effort is dedicated to 20% of the design requirements.

Applying the 80/20 rule is useful in allocating resources during the design process to target areas in design that result in substantial gains. For instance, the designers should focus on analyzing the performance requirements of the most critical applications. Effort should be spent also on lowering the cost of the most expensive components in the design. When deploying a new network or upgrading an existing one, priority should be given to implementing the most used services.

When resources are limited, focusing on aspects of the network design beyond the most critical 20% yields diminishing returns and should be avoided.

Read about other Network Design Principles.