Answer each of the following questions in the associated quiz on Blackboard, following the specified instructions. All answers will be automatically marked. The figure below illustrates a simple network map that included two (2) edges: Local Network (grey area) and Global Network (white area). In Local Network, the three (3) circuit switches: SC1, SC2 and SC3 are interconnected by two (2) links: LC1 and LC2. Each of these circuit links has three (3) slots. The hosts are each directly connected to one of the switches. In this part, we only need to know the communication scenario between Host A and Host B. The network has reserved one slot on each of the two links. In the figure below, the dedicated end-to-end connection uses the second slot in both links LC1 and LC2 (see the red coloured line). We assume that device C is the combination of modem and router in the Local Network, are connected together and connect to SC3 through LC3. The data transmission from device C in Local Network through L1 is considered the data from client C in the Global Network view.

In Global Network, packet-switches are used in the entirety of the network. We have a scenario where a client requests a web page from a remote server on a remote island via a slow satellite link above the earth in a geostationary orbit. There is one (1) client C, one (1) server S, and four (4) DNS servers: D1 is a Local DNS Server, D2 is a Root DNS Server, D3 is a Top-level Domain (TLD) DNS Server, and D4 is Authoritative DNS Server. We dont need to know where the Link L7 connect to in this assignment.

Scenario 1 Local Network Host A sends a file of 2,880,000 bits to Host B at the time t0 = 0 mili-second (msec). Link LC1 and link LC2 uses time-division multiplexing (TDM) with three (3) slots and have a bit rate of 9 Mbps. It needs 500 msecs to establish an end-to-end circuit before Host A can begin to transmit the file and the second (2nd) slot of the circuits in LC1 and LC2 is allocated for the transmission between Host A and Host B. At the time t0 + 500 msecs, the first (1st) slot of the circuits in LC1 and LC2 start to transmit. At the time t1, Host B has received all bits of the file from Host A. After 200 msecs from t1, Host B sends a file of 960,000 bits to Host A. Host A has received all bits of the file from Host B at time t2. There are some assumptions for the Local Network: 1. There is no propagation delays in this networking. 2. There is no transmission delays between A and SC1, as well as B and SC3. 3. The network starts with no data are transmissing at the time t0 = 0. 4. The slot of the circuits is allocated for the transmission can be used in both direction. 5. All switches have no processing delays (this is unrealistic, just to simplify calculations). Task: Answer the questions below in mili-seconds (msecs) rounded to three decimal places. Question 1: What is the value of t1? Question 2: What is the value of t2?

LC1 SC1 SC2 LC2 SC3 Si LC3 L1 C B Local Network Global Network L2 D2 L5 S3 L4 D1 S2 S4 L3 D3 L6 L7 D4 LC1 SC1 SC2 LC2 SC3 Si LC3 L1 C B Local Network Global Network L2 D2 L5 S3 L4 D1 S2 S4 L3 D3 L6 L7 D4