Subnetting vs. Supernetting: Splitting and Combining IP Blocks

Introduction: The Network Organizer

Most students learn about **Subnetting**—taking a large IP block (like a `/16`) and chopping it into smaller pieces for different departments. But what if a company wants to advertise its networks to the global internet? This requires the opposite skill: Supernetting (or Route Aggregation).

Cleaning up the Routing Table

If a university owns four sequential `/24` networks (e.g., 192.168.0.0 through 192.168.3.0), they *could* advertise all four separate routes to the world. But that is messy. By using Supernetting, they mathematically combine those four small networks into one single `/22` route. This shrinks the global routing table, saving memory for every router on Earth.

Conclusion

While subnetting divides for security, supernetting combines for efficiency. Both are vital for a clean network architecture. Test your subnet calculator here.