Exam 1 Reading Material

Exam 1 will be held March 5^th, as originally scheduled. Following is the review material for the exam.

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
• Good understanding of the end-to-end argument and how it applies in different networking environments and for different application requirements
• 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. Data Link Flow and Error Control

• Flow and Error Control-- ARQ Schemes
• Stop-and-Wait ARQ schemes
• Selective-Repeat
• Go-back-N ARQ
• Relevant Material:
• Lecture Notes
• You should be able to discuss different flow control strategies and solve problems related to their performance, similar to those asked in the homework assignments.
• Homework Assignments

3. End-to-End Flow Control

• You should be able t compare and contrast the different schemes that we discussed in class
• Open versus closed loop
• End-to-End versus Hop-by-Hop
• Hybrid approaches
• For each class, you need to understand the advantages and disadvantages of the flow control schemes. Given a network environment, you need to be able to argue what scheme is more appropriate for such an environment.

4. Congestion Control

• The focus should be on understanding the effects of congestion and the mechanisms used to deal with congestion.
• Impact of congestion on throughput and delay performance
• Congestion avoidance (Knee) vs. Congestion detection and recovery

· Congestion Control Techniques

§ Backpressure, Choke Packet, Implicit and Explicit Congestion Signaling

§ Packet-Pair and Rate-based Control Scheme

• Relevant Material:
• Lecture Notes
• You need to understand the relationship between window size, propagation delay and maximum throughput.
• Homework Assignments
• Be prepared to solve problems similar to the ones discussed in class and given in homework assignments.

5. Routing in Computer Networks

• Design issues in routing protocols
• Convergence, fairness, optimality,
• Understanding the difference and tradeoffs between routing in circuit-switching and packet-switching networks

• Understanding the difference between distance vector and link state protocols
• Asynchronous Bellman-Ford Algorithm vs. Dijkistra’s 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

6. Internet Architecture and Protocols

The focus should be on understanding the basic functionalities of Internet Protocols (IPv4) and relate these functionalities to the basic fields of the corresponding IP datagram:

• Principles of best-effort service
• How do the service semantics relate to E2E argument?
• What are the limitations of such a service
• Mobility, security, etc
• Fragmentation and reassembly
• Pros and Cons
• Stateful vs. Stateless Addressing
• Subnetting
• Variable Length Subnet Masks (VLSM)
• CIDR and “longest prefix matching”
• You should be able to develop an address scheme which meets best the requirements of an organization, in terms of number subnets, number of hosts per subnet, potential for extension in the future, etc.

7. 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.