P10. Consider a packet of length L that begins at end system A and travels over three links to a destination end system. 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. Assuming no queuing delays, in terms of di, Si, Ri, (i=1,2,3), and L, what is the total end-to-end delay for the packet? Suppose now the packet is 1,500 bytes, the propagation speed on all three links is 2.5-108m/s, the transmission rates of all three links are 2 Mbps, the packet switch processing delay is 3 msec, 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? P18. Perform a Traceroute between source and destination on the same continent at three different hours of the day. Video Note Using Traceroute to discover network paths and measure network delay a. Find the average and standard deviation of the round-trip delays at each of the three hours. b. Find the number of routers in the path at each of the three hours. Did the paths change during any of the hours? c. Try to identify the number of ISP networks that the Traceroute packets pass through from source to destination. Routers with similar names and/or similar IP addresses should be considered as part of the same ISP. In your experiments, do the largest delays occur at the peering interfaces between adjacent ISPs? d. Repeat the above for a source and destination on different continents. Compare the intra-continent and inter-continent results. P6. This elementary problem begins to explore propagation delay and transmission delay, two central concepts in data networking. Consider two hosts, A and B, connected by a single link of rate R bps. Suppose that the two hosts are separated by m meters, and suppose the propagation speed along the link is s meters/sec. Host A is to send a packet of size L bits to Host B. VideoNote Exploring propagation delay and transmission delay a. Express the propagation delay, dprop, in terms of m and s. b. Determine the transmission time of the packet, dirans, in terms of L and R. c. Ignoring processing and queuing delays, obtain an expression for the end-to-end delay. d. Suppose Host A begins to transmit the packet at time t=0. At time t= dirans, where is the last bit of the packet? e. Suppose aprop is greater than dirans. At time t=dtrans, where is the first bit of the packet? f. Suppose aprop is less than dirans. At time t=dtrans, where is the first bit of the packet? g. Suppose s=2.5-108, L=120 bits, and R=56 kbps. Find the distance m so that d prop equals dtrans.