Network

Selected

Questions

Chapter 7

7.4 Consider the use of 1000-bit frames on a 1-Mbps satellite channel with a 270-ms

delay.What is the maximum link utilization for

a. Stop-and-wait flow control? b. Continuous flow control with a window size of 7? c. Continuous flow control with a window size of 127?

d. Continuous flow control with a window size of 255?

7.6 A channel has a data rate of R bps and a propagation delay of t s/km. The distance

between the sending and receiving nodes is L kilometers. Nodes exchange fixed-size

frames of B bits. Find a formula that gives the minimum sequence field size of the frame

as a function of R, t, B, and L.(considering maximum utilization). Assume that ACK

frames are negligible in size and the processing at the nodes is instantaneous.

7.10 Two neighboring nodes (A and B) use a sliding-window protocol with a 3-bit

sequence number. As the ARQ mechanism, go-back-N is used with a window size of 4.

Assuming A is transmitting and B is receiving, show the window positions for the

following succession of events:

a. Before A sends any frames

b. After A sends frames 0, 1, 2 and receives acknowledgment from B for 0 and 1

c. After A sends frames 3, 4, and 5 and B acknowledges 4 and the ACK is

received by A

Chapter 10

10.4. What are the advantages of packet switching compared to circuit switching?

10.5. Explain the difference between datagram and virtual circuit operation.

10.6. What is the significance of packet size in a packet-switching network?

Chapter 12

12.2. What is fixed routing?

12.3. What is flooding?

12.4. What are the advantages and disadvantages of adaptive routing?

12.9 Apply Dijkstra’s routing algorithm to the networks in Figure 12.11. Provide a table

similar to Table 12.2a and a figure similar to Figure 12.9.

12.10 Repeat Problem 12.9 using the Bellman-Ford algorithm.

Chapter 13

13.3. Give a brief explanation of each of the congestion control techniques illustrated in

Figure 13.5.

13.5. Briefly explain the three general approaches to explicit congestion signaling.

13.3.

Chapter 15

15.2. What are the differences among backend LANs, SANs, and backbone LANs?

15.7. List and briefly define the services provided by LLC.

15.9. List some basic functions performed at the MAC layer.

15.4 Consider a baseband bus with a number of equally spaced stations with a data rate

of 10 Mbps and a bus length of 1 km.

a. What is the mean time to send a frame of 1000 bits to another station, measured from

the beginning of transmission to the end of reception? Assume a propagation speed of

200 m/µs.

b. If two stations begin to transmit at exactly the same time, their packets will interfere

with each other. If each transmitting station monitors the bus during transmission, how

long before it notices an interference, in seconds? In bit times?

Chapter 18

18.16 Is the subnet mask 255.255.0.255 valid for a Class A address?

18.17 Given a network address of 192.168.100.0 and a subnet mask of 255.255.255.192,

a. How many subnets are created?

b. How many hosts are there per subnet?

Number os subnets=2^ones in the last octet (Class c)

Number of hosts =2^zeros in the last octet