Q1) Advantage of packet switching vs. circuit switching.  Following figure illustrates that many users are sharing 1Mbps access link to Internet. Assume each user is either in active status which needed data access rate of 100kbps, or in silence status that user needs no data. Each user is active only 10% of time and users are independent with each other in their activities.

a) If circuit switching is utilized, how many user can this access link support?

b) If packet switching is utilized and there are 10 users. How frequently is this access link idle? How frequently does this link serve exactly two users?

c) If packet switching is utilized and there are 35 users, how frequently does access link be congested?  (Hint: the link is congested if and only if there are more than 10 users be active at the same time).