Problem 6 (10 pts). Consider a fictional six-layer protocol hierarchy where layer 1 is the lowest layer, and layer 6 is the highest layer. Therefore, an application sends a message M by passing it to layer 6. All the even-numbered layers attach a trailer T_i (i = 2, 4, 6) to their payload, and all the odd-numbered layers attach a header H_i (i = 1, 3, 5) to their payload. Draw the headers, trailers, and original message M in the order they are sent out.

Problem 7 (10+10 pts). Consider a packet of length L that begins at end system A and travels over three links to a destination end system B. These three links are connected by two packet switches. Let d_i, s_i, and R_i denote the length, propagation speed, and transmission rate of link i, for i = 1, 2, 3. The packet switch delays each packet by d_proc (known as the processing delay). Assuming no queuing delays, answer the following questions:

What is the total end-to-end delay for the packet? Write the answer in terms of d_i, s_i, and

R_i, (i = 1, 2, 3), and L.

Suppose now the packet is 1,500 bytes, the propagation speed on all three links is 2 10⁸m/s, the transmission rates of all three links are 3 Mbps (megabits per second), the packet switch processing delay is 2 msec (millisecond), the length of the first link is 5,000 km, the length of the second link is 4,000 km, and the length of the last link is 1,000 km. For these values, what is the end-to-end delay?