The path between two end systems consists of two routers and three links. The link between the routers has a data rate of 100Mbps and the two access-links connecting the end systems to their corresponding routers have a data rate of 20Mbps. Assume all packets in the network are 10,000 bits (including headers). Compute the time it takes to send a packet from one system to the other under the following conditions: a. Propagation delays are negligible and all router queues are empty.
b. Propagation delays are negligible and a packet encounters: 2 packets ahead of it when it arrives to the first queue and 3 packets ahead of it when it arrives to the second . In this case assume that the first packet in the queue is about to start transmission.
c. All router queues are empty but propagation delays are not negligible. The three links have lengths 2000Km, 4000Km and 2000Km, respectively and the signal propagation speed is 200x10^6 m/sec.