Problem 4 Transmission Delay (31 pts): Consider the figure below, with three links, each with the specified transmission rate and link length. Assume the speed of light propagation delay on each link is v=3108m/sec. A network layer PDU of length P=1000 Bytes is to be transmitted from A to B starting from time 0 . The PDU originates from the network layer at A, and is considered received when being processed by the network layer at B. Between the network and the DLC layers, the communications happen over a shared memory with read/write speed of 1Gbps on all nodes. Other than memory read/write, assume the processing delay is 0ms on all nodes. The DLC layer adds an overhead of 125 Bytes to the PDU, and the physical layer adds no additional overhead. Assume there is no queueing on any link before the transmission. Answer all time-related questions in milliseconds (ms). Note 1: Draw a time figure of the PDU(s) through all layers/links to determine the delays. Note 2: The DLC layer must completely read a packet from shared memory before transmitting it on the bitpipe, similarly the network layer software must completely read a packet from shared memory before forwarding it, and each layer must wait until a packet is completely available in shared memory before starting to read it. A. (3 pts) Assume there is no other transmission sharing any of the links. What is the bottleneck link bandwidth for this transmission? B. (3 pts) At what time T1 does the PDU leave A? A PDU leaves a router when it has been fully transmitted on to the next link. C. (3 pts) At what time T2 does the PDU leave R1? D. (3 pts) At what time T3 does the PDU leave R2? E. (3 pts) At what time T4 does the PDU reach B