BCF$\text{'}$s network involves modular organization, with buildings $($A and B$)$ and departments $($D$1$ to D$6)$ as distinct modules. A hierarchical arrangement ensures clarity and abstraction of unnecessary details. Each department's internal structure is encapsulated, and a top$-$down design approach is employed to address overall connectivity requirements. The design emphasizes clear interfaces, simplicity, and scalability while adhering to the specified user needs and utilizing public IP addresses for all computers.

explain where structured design is apparent in the text