A not fully connected mesh topology |

We have to find out how we can fix our model to support such a topology. The answer is: WE CAN'T unless we have a model for our software. So let us build a general model for the software.

OK, suppose there is a restriction in the application that any 4 small module can have full mesh connection and the whole application itself which contains many 4M units can have fully connected mesh topology for its 4Ms.

A 12 modules application decided to 3 fully connected mesh named as 4M and then a higher level of fully connected mesh for each 4Ms. |

From the previous post we had:

IDB1 =

*ψ*(n-1) (Σ Ei + Σ Ni) (1)

DDB1 =

*ε*Σ Ei +

*v*Σ Ni (2)

But for formula number (1) which is indirect development bugs, for each 4 small modules we have the following bug count:

IDB1 =

*ψ*(4-1) (Σ Ei + Σ Ni ) = 3

*ψ*(Σ Ei + Σ Ni)

Just remember the index 1 in all of the above is to show the evaluation of the formula at time t1 nothing else. We need it later to see what happens if we make repeated development during the time on software.

But if you look at the picture, we have another level of connection network which is also a fully connected mesh, so for this network the indirect development bugs will be:

IDB1 =

*ψ*(n/4-1) (Σ Ei + Σ Ni)

So the total IDB will be the sum of the 2 above:

IDB1 = 3

*ψ*(Σ Ei + Σ Ni) +

*ψ*(n/4-1) (Σ Ei + Σ Ni)

or

**IDB1 =**

*ψ*(n/4+2) (Σ Ei + Σ Ni) (5)
To compare 5 and 4 we need to see the behavior of terms (n-1) and (n/4+2), which is like the following:

0 < n < 4 → (n-1) < (n/4+2)

n = 4 → (n-1) = (n/4+2)

4 < n → (n-1) > (n/4+2)

**What does it say?**

*"If you are working on an application which has many modules, you need to think about the module connection topology or you will build a platform to distribute bugs across the application."*

Consider an application which has 100 modules, then the difference is 99 and 27 almost 4 to 1. We will talk about the better models and also try to have a more accurate calculation later.