We are sending a 20 Mbit test file from a source host to a destination host. All links in the path between source and destination have a transmission rate of 15 Mbps. Assume that the propagation speed is 2 * 108 meters/sec, and the distance between source and destination is 20,000 km.

a) Initially suppose there is only one link between source and destination. Also suppose that the entire file is sent as one packet. The end-to-end delay (transmission delay plus propagation delay) is?

b) Now suppose there are two links between source and destination, with one router connecting the two links. Each link is 10,000 km long. Again suppose the file is sent as one packet. Suppose there is no congestion, so that the packet is transmitted onto the second link as soon as the router receives the entire packet. The end-to-end delay (transmission delay plus propagation delay) is?

c) Now suppose there are two links between source and destination, with one router connecting the two links. Each link is 10,000 km long. Furthermore, suppose that the file is broken into 4 packets, each of 5 Mbit. Ignore headers that may be added to these packets. Also ignore router processing delays. Assuming store and forward packet switching at the router, the total end-to-end delay (transmission delay plus propagation delay) is?