Consider the problem of deciding whether to implement a virtual-circuit or a datagram network. Assume a network protocol that allows the system to operate as either a virtual circuit network or a datagram network. That is, its packet header format is specified such that it incorporates both a VCI and arbitrary source/destination addresses. When operating as a virtual circuit, it requires a 4-byte header. When operating as a datagram network, it requires a 40-byte header. Assume that there are 4 hops from source to destination, and that a set up or tear down request packet is 80 bytes (including the header). The total message length is 4096 bytes, the data rate is 9600 bps on all links and the packet size is 256 bytes (including the header). a) If we operate in the datagram mode, how long does it take for the first packet to reach the destination? b) If we operate in virtual-circuit mode, how long does it take for the first packet to reach the destination? c) Compute the end-to-end delay for datagram transmission? d) Compute the end-to-end delay for virtual-circuit transmission? Note: Queuing delays, propagation delays and acknowledgment delays are assumed negligible.