A node in a network has access to two data links (namely L1 and L2) to send its packets. It uses link L1 with probability p. Link L1 does not queue the transmitted packets (meaning that it always sends the received packets to the next node immediately); however, L2 queues the packets with probability q (as it serves more than one node). All the packets are sent eventually to the Internet and then they are received at the end-device and reassembled according to the protocol.
(a) What is the probability that a packet will be delayed (or queued) if p = 0.8 and q = 0.2?
(b) What is the probability that the delayed packet arrived at the end-device traversed through link L2?
(c) If the average delay through the Internet is 10 ms, the average queuing delay in L2 is 2 ms, and determine the average delay for a packet in the network assuming no other delay is incurred?