a) Maximum efficient: No Head-of-Line Blocking at all

b) Maximale Head-of-Line Blocking: use the Priorities of the Input Ports (E4>E3>E2>E1) we have to use output ports (A3 and A2) by queues with higher priorities, to achieve waiting time of the other queues

First tick: send b and d

Second tick: send a and c

Third tick: only now the heads of E2 and E1 will be released

c) SpeedUp of Switch Fabric

→ For this situation is sufficient the Speed-Up of Switch-Fabric x2. Requirement on Output Port: Buffer for 2 pakages for eack tick.

Normal speed 1x - one packet from one inport to one outport at one tick

SpeedUp 2x - switch fabric can process two packets from different inports to one output port

SpeedUp 5x - we can pass 5 packets to one output-port in one tick