After six years, we conquer scarcity 2 switches restraint undivided structure and 2 switches restraint another. Because, each switch enjoy 48 enjoyns and we scarcity 60 pcs to be conjoined in undivided structure. And past undivided enjoyn is used restraint union among the routers, we can enjoy simply 47 usable ports. So we scarcity undivided more switch in the identical structure to connect the retaining systems. Similarly restraint the relieve structure, we scarcity another brace switches. But we enjoy simply 3 switches to perform the upgradation. So it conquer be unusable to perform the upgradation.