problem 1: Compute the following:
A) Data is to be transmitted over the Public Switched Telephone Network (PSTN) by using 8 levels per signaling elements. If the bandwidth is 3000 Hz, deduce the theoretical maximum transfer rate.
B) Supposing that a communication line has a bandwidth of 3000 Hz and a typical signal to noise ratio of 20dB, find out the max theoretical information rate.
problem 2: Assume that a file of 35,000 characters is to be sent over the line at 55,000bps.
A) Compute the overhead in bits and time by using asynchronous transmission. Suppose 1 start bit and 1 stop bit and 8 bits to send the character itself for each character.
B) Compute the overhead in bits and time by using synchronous communication. Suppose that the data is sent in frames. Each frame comprises of 1000 bytes and overhead of 48 bits per frame for control, error detection and so on.
problem 3: Show that all work/logic employed in coming up with your answer for this problem
A) To provide more subnets, a Class B address is assigned the subnet mask of 255.255.240.0 How many hosts are possible per subnet.
B) What are the IP addresses used or spanned by the CIDR address 192.168.10.0/20?
C) The IP network 192.168.130.0 is using the subnet mask 255.255.255.224. What subnet are the given hosts on?
problem 4: Two hosts, one on East (host A) and one on the west coast (host B) of the USA are exchanging data. Assume that A is sending a large file to B. The file is split into packets of size 8000bits. The hosts are employing a stop-and-wait protocol. Thus A has to wait for an Ack before sending the next packet. They are joined by 1Gbps link. Suppose that the round trip delay between them is 30ms. Therefore the packet leaves A, reaches B and then an acknowledgement leaves B and reaches A. This round-trip takes 30ms.
A) Compute the throughput and link utilization.
B) To improve utilization, the hosts decide to use a sliding window protocol. Therefore they agree to send a bunch of packets which the receiver can acknowledge by sending one acknowledge packet. Suppose a full duplex connection (that is, A and B and simultaneous exchange data with one other). If sliding window size is 50 packets then what happens to throughput and utilization?
C) What should be the sliding window size for the link utilization to be 100%?
problem 5: CSMA/CD based Ethernet LANs in different sites and Frame Relay (FR) service to connect them altogether. You want to make a difference in the organization by upgrading the LANs to be more scalable, better accessible and compatible with future initiatives like private cloud. You are preparing a report to board of VPs about your proposal. Answer the given problems about your proposal:
A) List at least three shortcomings of the current CSMA/CD based Ethernet LAN.
B) prepare down at least four technological enhancements that you propose for the wire line LAN infrastructure.
C) prepare down at least two benefits and two issues of adding a wireless LAN for the organization.
problem 6: In this problem, you will compare delays in packet switching (that is, in IP networks), in circuit switches (that is, in PSTN telephony) and in virtual circuit packet switching (that is, in FR networks). Suppose that the following parameters are defined for switching networks:
N: number of hops between two end points
L: message length in bits
B: data rate in bits per second (same on all links)
P: fixed packet size in bits
H: overhead (header) bits per packet
S: call setup time (in circuit switching and in virtual circuit) in seconds
D: propagation delay per hop in seconds
F: processing delay per packet per hop in packet switching.
Suppose the processing delay per packet per hop in virtual circuit packet switching is F/3 (packets are generally referred to as frames in virtual circuit packet switching). Do the given:
A) By using the defined parameters above, derive a mathematical expression showing under what condition the packet switching delay is equivalent or less than circuit switching delay.
B) By using the defined parameters above, derive a mathematical expression showing under what condition the virtual circuit packet switching delay is equivalent or less than packet switching delay.
Suppose that there are no acknowledgements. Show your steps in deriving your equations or expressions.
problem 7: Do the given problem
A) Consider a local telephone company offering triple-play (TV, Internet and Phone) services to the residential customers in a single metropolitan area. What might be the reasons that such a company loses its revenue and profits? Consider the persuade of changing business models, technological enhancements and regulations for answering this problem. You may suppose that the company owns the local loops and the switching equipment for its service in the area.
B) Assume that you are the new CEO of the local company in part (A). The company is committed to stay in business and increase the revenue. You are asked to present your strategy to the board of directors of the company. Suggest three new initiatives to keep you in business grow in revenue and increase profit. Briefly describe their pros and cons.
A) Assume that you are the new regulator in charge who has authority over Internet services (though in reality such a position might not exist depending on your country). You aim to improve the competition among the Internet Service Providers (ISP) and as well want to promote new competitive ISPs to emerge. describe two competition models which you could propose to further your objectives. Describe briefly the impact of your proposals on existing ISPs. Describe briefly the pros and cons of your models.
B) Your company is in the business of offering high speed Internet Access all along with other services like Web Hosting. You are the product manager who designs product and service plans to small and medium business in downtown. You realize that providing one product-price plan to all is not sufficient and that you can raise profits by offering smart product bundles. After conducting a small survey, you find that some firms (totaling 20) are willing to pay $49.99/ per month for a reliable high speed Internet while others (another 20) can pay as much as $59.99. [Suppose that consumer’s willingness to pay – price = Consumer Surplus. Users always select a product or product bundle that gives them higher Consumer Surplus].
i) Is there any way you can sell two different price plans to such businesses? Why? Why not? What are your profits?
ii) You as well find from your survey that firms who are willing to pay higher are as well interested in web hosting and can pay another $20 for it. Now, can you design some product plans to raise your profits? What are those plans and what is the profit?