Consider a packet of length L which begins at end system A and travels over three links to a destination end system using packet switching. These three links are connected by two packet switches. Let di, Si, and Ridenote the length, propagation speed, and the transmission rate of link i, for i = 1, 2, 3. The packet switch delays each packet by dproc. a) Draw a time evolution schematic of his transmission. The vertical line represent time (4 veridical lines representing systems 1, 2, 3 and 4). The picture should be roughly proportional to scale (i.e., a segment representing 18 msec should be roughly 3 times of a segment representing 6 msec). b) Assuming no queuing delays in in nodes, in terms of di, si, Ri (i = 1, 2, 3), and L, what is the formula for the total end-to-end delay for the packet? Assume dproc for the First node is 0. c) Suppose now the packet is 2,500 bytes, the propagation speed on all three links is 2.5x108 m/s (or 250,000 kilometers/second), the transmission rates of all three links are 2 Mbps, the packet switch processing delay is 1 msec, the length of the first link is 10,000 km, the length of the second link is 8,000 km, and the length of the last link is 2,000 km. For these values, what is the end-to-end delay? d) Now suppose R1 = R2 = R3 = R and dproc = 0. Further suppose the packet switch does not store-and-forward packets but instead immediately transmits each hit it receives before waiting for the entire packet to arrive. Note that with these assumptions the transmission acts similar to circuit switched transmission (almost, details are a bit different). Show the time evolution of this system (similar to part (a) above). e) What is the end-to-end delay of the transmission in part (d)