Question $3$: Consider the network below.

$($a$)$ Show the forwarding table in router A$,$ such that all traffic destined to host H$3$ is forwarded through interface $3.$

$($b$)$ Can you write down a forwarding table in router A $,$ such that all traffic from H $1$ destined to host H$3$ is forwarded through interface $3,$ while all traffic from H$2$ destined to host H$3$ is forwarded through interface $4?$

Question $4$: Suppose two packets arrive to two different input ports of a router at exactly the same time. Also suppose there are no other packets anywhere in the router.

$($a$)$ Suppose the two packets are to be forwarded to two different output ports. Is it possible to forward the two packets through the switch fabric at the same time when the fabric uses a shared bus? Justify your answer.

$($b$)$ Suppose the two packets are to be forwarded to two different output ports. Is it possible to forward the two packets through the switch fabric at the same time when the fabric uses switching via memory? Justify your answer.

$($c$)$ Suppose the two packets are to be forwarded to the same output port. Is it possible to forward the two packets through the switch fabric at the same time when the fabric uses a crossbar? Justify your answer.