Answer Happy

QUESTION 2 (12 MARKS) Traditional packet switches, or routers, have used FIFO (First In, First Out) queueing strategies to share switching resources across their input ports. a) In what way might the FIFO strategy NOT be fair? In providing your answer, give an example of how one stream could "hog" the switching resources, crowding other streams out. [4 marks] b) An alternative strategy is "Round Robin" or "Fair Queueing", in which packets (if present) are read from each input port in turn (i.e. in a cycle) and forwarded to their destination output port. Explain why this strategy also might not be completely fair across input data streams, and again use an example to show how one stream could "hog" the switching resources. [4 marks] c) A further queueing strategy refinement is "Bit Rate Fair Queueing". Explain how this differs from the Round Robin approach discussed in b) above, and explain why it could be considered more fair. [4 marks]