For this question, let the packet size L = 1000 bytes, the propagation speed s = 2.5 x 108 m/s, the link distance d = 2000 km, and the transmission rate R = 10 Mbps. For circuit switching, the setup time is 5 ms, and each link supports 10 circuits. One of the factors that needs to be considered is the setup time for the circuit (being the time for each switch to connect the correct inbound and outbound circuits). In this case the setup time provided is for the complete circuit to be formed and can be included in the total delay as a single factor. Assume that 1 Mbyte (megabyte) = 1 x 106 bytes (SI definition). Be mindful of units. Answer the following:

a)

Given a file of 1 MB, how long does it take to send it between two hosts that are connected with 4 datagram, packet switched links where the switches use store-and-forward? In a packet switched network, data needs to be encapsulated (information regarding addressing) needs to be added. Assume each packet has a header size of 50 bytes in addition to its data payload of 1000 bytes.

b) How long does it take to transfer the 1 MB file if store-and-forward is not used (assume that packet can flow through the switch without delay)?