Final answer:
To describe the joint pmf of X1, ..., X8, we can construct a discrete probability mass function (pmf) table with columns for each Xi and their corresponding probabilities P(Xi). The sum of all probabilities should equal 1.
Step-by-step explanation:
The joint pmf of X1, ..., X8 can be described using a discrete probability mass function (pmf) table. Each Xi represents the number of packets routed to output port i. Since X takes on values 0, 1, 2, 3, 4, and 5, we can construct a table with columns for each Xi and their corresponding probabilities P(Xi). The sum of all probabilities should equal 1.