a)Consider a 1 Mb/s circuit-switched path between two stations A & B and the path consists of five switching nodes in between. It needs 1.2 seconds to set up the circuit (i.e., completion of the call setup and accept) before transmitting any data or voice signals. Further assume that A and B is of 3 km apart and the signal propagation speed is 2 108 m/s. Suppose we are using this path to transmit a 4 MiB file (4 220 ) from A to B. Assume the circuit does not exist yet, how long it will take to deliver this file to B using this channel? Give your answer in full precision.

b)If the above circuit-switched path is replaced by a packet-switched system with five packet switches utilizing 1.5 Mbps links. How long does it take to transfer the same amount of data (4 MiB)? Assuming that there is no queuing delay at any of the switches, but each switch needs 10 micro-seconds to process a packet. Further assume that each packet has a header of size 40 bytes and can carry at most 2048 bytes of data payload. Give your answer in full precision.