When we can already create several subnets on a single switch and users connected to various subnets are unable to interact with one another, why do we need virtual LANs? An explanation of your response should be provided, along with an illustration using a topology-related example.

In light of the present situation of the business, please provide a succinct description of the advantages and cons associated with connectionless protocols in contrast to connection-based protocols.

Destination IP-based forwarding is used by the per-router control plane (sometimes called the classical network) to connect with other routers. If messages are forwarded depending on their destinations' IP addresses, what are the boundaries of this approach? Include a description of at least three limitations, preferably with examples. To what extent does Software-Defined Networking (SDN) contribute to solving these problems? The examples will serve as the explanation.

Ethernet, for example, is a connectionless protocol that specifies the path taken by a packet between its source and destination addresses. However, a protocol that is connection-oriented, such as ATM, specifies the path taken by a cell using virtual connection IDs (VPIs and VCIs). Could you please elaborate on this statement?