scuba chat

I have to make a code for the scuba chat. I have the template for the code and I only need to make a code which control the packets on the physical layer by adding on the template.
The code has to satisty at least 2 requirements out of 4(segmentation and reassembly, medium access control, multi-hop broadcasting, reliable data transfer) to pass the assignment.
In the description, it says that I have to make a simple interface but don’t think about that.