Application Layer Services

Task

Provide short answers to the following six questions. Your answers should be clear, concise and to the point. Prepare a single document (MS Word or PDF, NOT both) along with title page and submit it online using Turnitin.

Question 1: Discuss the advantages and disadvantages of star, bus, and mesh physical topologies. Provide real examples of each type. (5 marks)

Question 2: Explain encapsulation and decapsulation in a five layer TCP/IP protocol suite. How does multiplexing and de-multiplexing differ from encapsulation and decapsulation? (5 Marks)

Question 3: Calculate the approximate bit rate and signal level(s) for a 6.8 MHz bandwidth system with a signal to noise ratio of 132. (5 Marks)

Question 4: Explain why the OSI model is better than the TCP/IP model. Why hasn’t it taken over from the TCP/IP model? Discuss the advantages and disadvantages of both models. (5 Marks)

Question 5: What is the total delay (latency) for a frame of size 5 million bits that is being sent on a link with 10 routers each having a queuing time of 3.5 µs and a processing time of 1.8 µs. The length of the link is 1900 km, the speed of light inside the link is 2.2 x 108 m/s, the link has a bandwidth of 8 Mbps. Which component(s) of the total delay is/are dominant? Which one(s) is/are negligible? (5 Marks)

Question 6: According to RFC1939, a POP3 session is one of the following states: closed, authorization, transaction or update. Draw a diagram and explain to show these four states and how POP3 moves between them. (5 Marks)

Rationale

This assessment consists of six questions assessing a basic understanding of network & data communication models, next generation IP and application layer paradigm. This assessment covers the following learning objectives: define and explain various Internet technologies; describe and analyse the role and importance of Internet technologies in the modern world; and explain how different application layer services such as client-server and peer-to-peer paradigms work in the Internet.