6 Ridiculous Rules about Computer Network Diagram

Computer Network

The network diagram is used for a visual representation of your network architecture. It makes easier to understand how the different components in a network are connected with each other.

In this way one gets an overview of how the complete network will look like and thus many mistakes can be identified in early stages by using such network diagrams.

To draw a network diagram you must follow some rules. You must also have some good knowledge of networks and networking.

This article will let you know about rules to create a network diagram. Some main rules that you will read in detail in this article are:

  1. Length of arrow
  2. Representing a single activity once only
  3. Follow a logical sequence
  4. Duplication in event numbers
  5. Different end event
  6. Avoiding looping and dangling errors

Before moving towards the rules for creating network diagram you must be familiar with some important term used in this article.


It is an action that is required to complete a task. It is represented by an arrow in the diagram


It occurs at the start and end of the activity. It does not consume any resource.

Rules for Creating Network Diagram:

1) Length of the Arrow:

Network diagrams are basically of two types. The arrow network diagram and the node diagram.

To know more about activity on node read this.

Arrow network diagram is also referred to as Activity on the arrow. In this diagram, we use arrows to represent activities.

The rule associated with this diagram is that the arrow length depicts the duration of the activity.

The tail of arrow denotes the start of the activity and its head represents the end of the activity.


(Image = Arrow network diagram)

It is a sample network diagram.

In this diagram, it is assumed that all duration is in days. So A=2, B=1, C=3 means that the activity A has a duration of 2 days, activity B has a duration of 1day, activity C has a duration of 3 days and so on.

2) Representing a Single Activity Once Only:

We can represent an activity in a network diagram once only.  Representing an activity in a network diagram more than once is against the rules.

3) Follow a Logical Sequence:

This means that activities must follow an interrelationship among them. The one with the lowest value (of value 1) is the start event and the activity with the highest value is the end event.

All activities preceding an activity must be completed before that activity starts. Thus they follow a logical sequence.

Although dummy activity doesn’t use any resource of time it needs to follow this rule also.

4) Duplication in Event Numbers:

Event in the diagram is basically the project milestone. Do not use the same event numbers again and again in a network diagram.

The numbering is done from left to right and from top to bottom.

An activity must not be duplicated. All activities must be represented by their own symbols.

Make sure that there is one start event and one end event in a network

5) Different End Event:

If two activities are starting from a tail event then you need to make sure that they do not have a common end event. To make it correct you can use a dummy activity.


(Image = Different end event)

Consider the two figures in the network diagram above. The fig A is incorrect as the 2 activities have the same end whereas the fig B is correct.

6) Avoid Looping and Dangling Errors:

Looping error:

It is also referred to as the cyclic error. It is caused because of endless lopping in the diagram.

Dangling error:

This error arises due to presence of a disconnected activity in a diagram

(Image = Dangling error)

The figure above shows dangling error.

Advantages of Computer Network Diagram:

Its some benefits include:

  • Planning
  • Identifying important activities.
  • Quite helpful in cash flow too.

Final Thoughts:

Network diagram works as the guideline for creating a project.  It is necessary to create network diagram before starting the project, as it guides the project manager in many aspects. In a nutshell, it gives a better understanding of the project.