$2.[$Packet Scheduling, $15$ pt$]$ Consider the pattern of red and green packet arrivals to a router's output port queue, shown below.

arr

pacl

se

depart

Suppose each packet takes one time slot to be transmitted and can only begin transmission at the beginning of a time slot after its arrival. Indicate the sequence of departing packet numbers $($e$.$g$.,$ at $\backslash ($ t$=1,2,3,4,5,7,8\backslash ))$ under each of the following scheduling policies:

a$.$ FCFS

b$.$ Priority $($where red packets always have higher priority$)$

c$.$ Round Robin $($where red packet starts a round if there are both red and green packets ready to transmit after an empty slot$)$

Then suppose each packet takes two time slots to be transmitted and can only begin transmission at the beginning of a time slot after its arrival. Indicate the sequence of the first four departing packet numbers $($e$.$g$.,$ at $\backslash ($ t$=2,4,6,8\backslash ))$ under each of the following scheduling policies:

d$.$ Priority $($where red packets always have higher priority$)$

e$.$ Round Robin $($where red packet starts a round if there are both red and green packets ready to transmit after an empty slot$)$