Course Description

The Internet is one of the most transformative technologies of our time—powering everything from communication and commerce to entertainment and education. But how does it actually work?

This course offers a comprehensive introduction to the design and implementation of computer networks, with a focus on the Internet. You will learn how data moves across the globe, from your laptop to services like Google and Netflix, and what happens at each step along the way. The course includes hands-on programming assignments and team projects to give you practical experience in network design and operation.

This is an introductory course — no prior networking experience is required.

Learning Outcomes

By the end of the course, you will be able to:

• Understand how the Internet works end-to-end.
• Build and operate a simplified Internet-like network.
• Evaluate the performance and reliability of a network, using appropriate metrics.
• Propose improvements or design alternatives for better performance or reliability.
• Recognize ML concepts to model or enhance networking tasks.
• Identify potential security threats in real-world networks.

Staff and office hours

Textbook

James Kurose and Keith Ross, Computer Networking: A Top-Down Approach

Grading

The grade breakdown is:

• 40% final exam
• 35% project 1 (Internet Routing)
• 25% project 2 (Reliable Communication)
• bonus for class participation

There is no midterm exam.

Lectures

Lectures meet on Tuesday and Thursday 9:00 am – 10:20 am in ComSciBldg 104.

Projects Policy

Collaboration. Projects must be done in groups (of two or three partners). Refer to the collaboration policy so that you collaborate only as authorized.

Electronic submission. Projects are submitted electronically through Github. You may submit as many times as you'd like until the deadline; we will grade your most recent submission. Group submissions must have all group members attached to the submission. Resubmitting a group project requires reattaching all group members.

Expectations. COS 461/ECE 471 is a 400-level course with expectations to match. Students should not only expect to be held to higher standards, but should also expect less hand-holding in general than they may find in 300-level courses and below. Students should not expect course staff via Ed or office hours to perform code reviews for correctness as a substitute for their own unit testing design review or directly provide/confirm answers to project problems. For programming components, course staff reserves the right to run hidden test cases that will not be revealed until grades are returned. Please do not ask course staff to reveal any information about hidden tests. Course staff are happy to help explain course concepts, clarify project specifications provided they are not intentionally vague, provide a starting hint, and offer suggestions for unit testing. Some course staff are also happy to provide modest debugging assistance once students understand the solution at a high level, but ultimately students are responsible for debugging their own code.

Regrades. If you believe that the course staff made an objective error in grading, then you may submit a regrade request. Subjective disagreements with rubric items or their values are not grading errors. Any other questions or discussions related to project grading should be directed to Ed or office hours. Regrade requests are due one week after project grades are returned.

Late policy. Projects that are submitted after the specified due date will lose 20% of the full project grade for the first day (or partial day) of lateness and 10% with each additional day with a maximum of 50% loss. We won't accept homework more than seven days late.

Extensions. We will grant extensions only in the case of unforeseeable circumstances like medical emergencies, as documented by your Dean or Director of Studies and our approval.

Collaboration Policy

This course permits many forms of collaboration, including help from course staff, classmates, and lab TAs. However, you must be careful to collaborate only as authorized below. Here is a summary, where ✔ means YES and ❌ means NO. If you have any questions, please contact the course staff.

activity	your group	course staff	COS 461/ ECE 471 grads	classmates	AI chatbots	other
discuss concepts with ...	✔	✔	✔	✔	✔	✔
acknowledge collaboration with ...	✔	✔	✔	✔	✔	✔
expose solutions to ...	✔	✔	❌	❌	❌	❌
view solutions from ...	✔	❌	❌	❌	❌	❌
plagiarize code from ...	❌	❌	❌	❌	❌	❌

Your solutions. The term solutions refers to any of the products created when completing a programming project, such as source code (including comments) and any text files. It includes both finished and unfinished products, regardless of correctness or completeness.

• You must never expose solutions to anyone who is taking COS 461/ECE 471 now or who might take COS 461/ECE 471 in the future. Do not post solutions in public code repositories.
• If you leave your computer unattended, be sure to protect it with a password.
• You must never receive or view another group's solutions to a programming project (or variant of an project).
• Attempting to decompile or otherwise gain information about the implementation of any provided solution archives or binaries is an explicit violation of this policy.

Working Groups. All projects require you to work in groups. Here are the rules regarding group work.

• A group must consist of either two or three people. Solutions turned in by a group of one person, or by a group of four or more people, will receive no credit.
• You can work in different groups on different projects.
• Each group should submit a single solution, which should be clearly labeled with the names of the group's members. Only one member of the group needs to submit the group's solution. There is no need to submit redundant copies for the other members.
• The members of a group will all receive the same grade on an project, reflecting the quality of the group's collective solution to the project.
• It is up to you to divide up the work within your group, and to make sure that the other members of your group meet their commitments. (If a member of your group is consistently irresponsible, let us know and we'll take appropriate action.)
• If you have trouble finding a group, let us know and we will help you.

Why Work in Groups? There are several reasons for our decision to make you work in groups.

• In the real world, people work in groups. We want you to learn how.
• We think that students learn more by doing hard projects than by doing easy ones. Giving group projects lets us give harder projects without overworking you.
• Networking problems require you to deal with engineering tradeoffs and make difficult design decisions. We hope that you'll debate these decisions within your group, and that the debates will be educational.

A note about StackExchange, Wikipedia, or online forums. Many of the topics in this course require self-teaching. This includes a lot of searching online for documentation and information about algorithms, technologies, and techniques. Unfortunately, this includes a wide gray area between learning and plagiarism. Don't be afraid of searching for and using online resources that teach you how to do something that is not a direct requirement of an project.

Use of LLMs (Large Language Models). You may use LLMs (e.g., ChatGPT, GitHub Copilot) as a tool for brainstorming, clarifying concepts, or debugging, provided you:

• Clearly document any use (exact prompt) in your code or reports (e.g., include a comment: “Used ChatGPT to explain TCP checksum calculation”).
• Do not copy/paste full solutions to projects from LLMs.
• Understand and are able to explain any output you incorporate.

Plagiarism. As members of the University community, students are bound by the rules and procedures described in Rights, Rules, Responsibilities.

All the rules above continue to apply after projects are graded and after the end of the semester.