Task $6$: Before implementing a security policy, the network manager requires an understanding of the network layer protocols. Within the TCP$/$IP protocol stack, describe the specific protocol operating at the network layer. Additionally, use Packet Tracer to simulate a communication process between a PC in one branch to a PC in a different branch or region. Provide detailed explanations and, if possible, include screenshots. Address the following aspects:

a$.$ Identify the network devices involved in the data flow.

b$.$ Specify the interfaces utilized in the communication process.

c$.$ Addresses $($IP and MAC address$)$ used in the communication.

d$.$ Protocols needed for communication and what these protocols are used for.