(a) Data flow can be unidirectional or bidirectional, give examples of such data flow. Also, mention the layer responsible for deciding on the type of data flow. (3 Marks) (b) Source (S) is sending a Message (M) to Destination (D) via a Router (R1). S and D belong to LAN1 and LAN2 respectively. Depict this scenario and show the contents of the packets, frames and raw bits included in the header of network, data link and physical layer at each hop interface (6 Marks) (c) If too many packets are present in the network at the same time, there is a possibility of bottle neck to arise. Mention the layer which take care of this issue. (1 Mark)