Exam Review Material

Exam 1 will be held on February 28^th, as originally scheduled. The main topics to be covered in the exam are:

1. Fundamentals
• Protocol Architecture and Layering

Understand the basic functionalities of each layer

Understand the concept of layering and the way layers interact with other

Issues include multiplexing, segmentation and reassembly, encapsulation, error and flow control, routing and congestion control.

• Switching Techniques.

Datagram vs. Message Switching vs. Circuit Switching

Comparison of the switching techniques in terms of the service they provide

Analysis of these techniques in terms of delays and overhead

• Connection-Oriented vs. Connectionless

Service semantics and design issues related to each paradigm

• Impact of bandwidth and physical characteristics on network design issues
• Understanding of the end-to-end argument and how it applies in different networking environments and for different application requirements
• Understanding of the main design issues that impact and differentiate multi-service, high-speed networks from earlier data communication networks

Fundamental and practical understanding of the simple models of reliability and flow control in high speed networks presented in the lecture notes

Ability to reason and discuss the impact of reliability and flow control on the network architecture and protocol design.

• End-to-End argument and its role in designing network architecture
• You should be able to work out problems similar to the ones asked in homework assignments.
• Concepts such as propagation delay, transmission time and queuing delay should be well understood.
• Relevant Material

Lecture notes (Introduction)

Homework Assignments

2. Routing in Computer Networks
• Design issues in routing protocols

Convergence, fairness, optimality objectives

• Understand the difference and tradeoffs between routing in circuit-switching and packet-switching networks
• Be able to derive expression for traffic routing to achieve optimality and fairness for a given network topology and traffic patterns
• Distance vector and link state protocols: Asynchronous Bellman-Ford Algorithm vs. Dijkstra Algorithm

Understand The difference between the two approaches, in terms of overhead, convergence rate, and handling loops

Understand and discuss the mechanisms to deal with loops: split horizon, poison reverse, etc.

• Relevant Material

Lecture Notes

Homework Assignments

3. End-to-End Flow Control
• Objectives of an End-to-End Flow Control
• Reactive and Preventive Control
• Why closed-loop control is problematic in high speed networks?
• Levels of control - packet level, connection level, and associated design issues.
• Understand the design and implementation of a basic sliding window protocol, including data structure, invariants, etc.

Discuss and derive the maximum throughput that can be achieved using a basic sliding window protocol, as a function of the round-trip delay, packet transmission time and window size.

• Understand the basic properties of an exponentially smoothed average algorithm and how it is used to estimate rates in end-to-flow control.
• Relevant Material

Lecture notes

Supplemental homework assignment

4. Internet Architecture and Protocols
• Understanding the basic functionalities of Internet Protocols (IPv4) and relate these functionalities to fields of the IP datagram:
• Principles of best-effort service

How do the service semantics relate to E2E argument?

What are the limitations of such a service with respect to mobility, security, etc

• Fragmentation and reassembly

Pros and Cons

• IP Addressing

Stateful Addressing and limitation

5. Homework Practice
• The test will involve problems very similar to what has been asked in the homework assignments and practice assignment. You are strongly encouraged to re-work these problems and understand the techniques used for their solutions.

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