CS 3700 - Networks and Distributed Systems

General Information

Professors: Alden Jackson, Alan Mislove, and Christo Wilson
Location and Time: Alden: Online, Monday/Wednesday 2:50pm - 4:30pm (East Village 008)
Alan: In Person, Tuesday 11:45am - 1:25pm, Thursday 2:50pm - 4:30pm, ISEC 102
Christo: In Person, Monday/Thursday 11:45am - 1:25pm, Shillman Hall 220
Professor Office Hours: Alden: TBA
Alan: TBA
Christo: TBA
Teaching Assistants: TBA
TA Emails: TBA
TA Office Hours: TBA
Class Forum: On Piazza

Course Description

The Internet has become an integral part of modern society. We are constantly connected by smart, mobile devices backed by large-scale, cloud-based infrastructure. Thus, it has become critically important for computer scientists to be familiar with the fundamentals of computer networking, and the design principals behind distributed systems that leverage the network. This course will focus on the architecture, algorithms, and protocols of the Internet, as well as key design principals of distributed systems. Topics include local area networking, routing, congestion control, the domain name system, network security, and applications such as distributed key-value stores, peer-to-peer and content distribution networks, and crypto-currencies. This course will be systems oriented, and students will work on hands-on projects to learn how to build and understand Internet applications.

Which Section of 3700 Is This?

All of them. There are three sections of CS 3700 running in Fall 2020, being taught by Alden Jackson, Alan Mislove, and Christo Wilson. All three sections will be covering the same material, following the same schedule (roughly), using the same homeworks and projects, and sharing the same TAs.


CS 3700 will be following the NUFlex online/offline hybrid teaching format to accommodate the needs of students and instructors during the ongoing COVID-19 pandemic. What this means is that the course will be run in a way that accommodates in-person, online synchronous, and online asynchronous participation.

With respect to lectures:

Students planning to attend lectures in-person are expected to stagger their attendance in accordance with Northeastern's dynamic scheduling policy.

All homeworks and projects will be available online, can be completed entirely online, and will be turned in online. More details on homeworks and projects is available below.


Parts of this course will be recorded for educational purposes. These recordings will be made available only to students enrolled in the course, the instructors, and teaching assistants assigned to the course.

Only students who have arranged an accommodation with the Disability Resource Center may use mechanical or electronic transcribing, recording, or communication devices in the classroom. Students with disabilities who believe they may need such an accommodation may contact the Disabilities Resource Center.

COVID-19 Safety and Accommodations

We expect all students to do their utmost to protect the safety of their peers and instructors during these unprecedented times. This includes abiding by all safety guidelines as stated in Northeastern's safe reopening policy.

We will be enforcing mask requirements for all students attending class in person. We will all be wearing masks. Students who arrive to class without a mask will be told to leave until they can procure a mask.

We will be enforcing social distancing requirements for all students attending class in person. Students are expected to maintain a six foot distance from others. Students who violate the distancing policy will be asked to move, and if they fail to comply will be told to leave.

We realize that the ongoing pandemic makes it difficult to predict what will happen in the future, or how events may impact students' ability to attend lectures and/or turn in assignments on time. Recorded lectures will be posted online so that students who cannot attend live lectures may review them later. Students facing hardship that prevent them from completing an assignment on time should contact their professor and explain the situation. All reasonable requests will be honored.


The official prerequisites for this course is CS 2510. That said, this course is systems oriented, so we expect you to understand the basics of computer architecture and operating systems, and to have experience implementing non-trivial systems-type projects. Basic knowledge of the Unix command line is essential. You should know how to write code using emacs/vim, write a makefile, compile code using makefiles, check for running processes, kill runaway processes, and create compressed archives. Experience with a debugger is recommended.

Class Forum

The class forum is on Piazza. Why Piazza? Because they have a nice web interface as well as iPhone and Android apps. Piazza is the best place to ask questions about projects, programming, debugging issues, etc. To keep things organized, please tag all posts with the appropriate hashtags, e.g. #lecture1, #project3, etc. We will also use Piazza to broadcast announcements to the class. Bottom line: unless you have a private problem, post to Piazza before writing an email to the TAs or instructors.

Schedule and Lecture Slides

Dates Slides Readings Homework Projects
Sept. 8-11 Intro, History Beej's Guide
Sept. 14-18 Network Architecture, Physical Layer Data Link Layer §1.1-1.6, 2.1-2.3, §2.4-2.8 Proj. 1 Due Sept. 18
Sept. 21-25 Data Link Layer, Bridging and Switching §3.1, 3.4 Hw 1 Due Sept. 25
Sept. 28-Oct. 2 Bridging and Switching, Network Layer §3.2 Proj. 2 Due Oct. 2
Oct. 5-9 Network Layer, Intra-domain Routing §3.3 Hw. 2 Due Oct. 9
Oct. 13-16 Inter-domain Routing §4.1 Proj. 3 Milestone Due Oct. 16
Oct. 19-23 Transport Layer §5.1-5.2, 6.1-6.4 Hw 3 Due Oct. 23 Proj. 3 Due Oct. 23
Oct. 26-30 NAT, DNS §9.3 Hw. 4 Due Oct. 30
Nov. 2-6 Distributed Systems Overview, Web Architecture †5; §9.1 Hw. 5 Due Nov. 6 Proj. 4 Due Nov. 6
Nov. 9-13 Web Architecture, Time and Logical Clocks §9.4; †10.4-10.7, 14 Hw 6 Due Nov. 13
Nov. 16-20 Fault Tolerance and Consensus §8 Hw 7 Due Nov. 20 Proj. 5 Due Nov. 20
Nov. 23-24 P2P and BitTorrent §9.4; †10.4-10.7, 14
Nov. 30-Dec. 4 P2P and BitTorrent, Overlay Networks Hw 8 Due Dec. 4 Proj. 6 Milestone Due Dec. 4
Dec. 7-9 Transport Layer Security, Bitcoin, Anonymous Communication Hw 9 Due Dec. 11
Dec. 14-18 Finals Week Hw 10 Due Dec. 15 Proj. 6 Due Dec. 18


We do not require students to get textbooks; everything you need to know for this course can be found in the slides or online. However, a textbook may be useful if you are not totally comfortable with network fundamentals, or if you just want to have a handy reference book. Officially, the networking textbook for the course is:

Computer Networks: A Systems Approach, 5th Edition
by Larry Peterson and Bruce Davie, Morgan Kaufmann.
There is also a supplement:
TCP/IP Sockets in C
by Jeff Donahoo and Ken Calvert, Morgan Kaufmann.
Also recommended, for reference:
Computer Networking: A Top-Down Approach Featuring the Internet.
by Jim Kurose and Keith Ross, Addison-Wesley.
We also have an official distributed systems book, although it is not as good as the Peterson/Davie networking textbook:
Distributed Systems: Concepts and Design, 5th Edition
by George Coulouris, Jean Dollimore, Tim Kindberg, and Gordon Blair, Pearson.
Note that, should you choose to purchase these textbooks, older editions are totally fine.


There will be six programming projects throughout the semester. Programming projects are due at 11:59:59pm on the specified date. You will use a turn-in script to create a compressed archive of the project files, timestamp them, and submit them for grading. These projects require significant design and coding, hence we strongly recommend that students start early!

Assignment Description Group? Due Date Piazza Tag % of Final Grade
Project 1 Socket Basics No September 18 #project1 5%
Project 2 FTP Client No October 2 #project2 10%
Project 3 Building a Router Yes October 23 #project3 15%
Project 4 Reliable Transport Yes November 6 #project4 15%
Project 5 Web Crawling Yes November 20 #project5 10%
Project 6 Distributed Key-Value Store Yes December 18 #project6 15%

Project Groups

Four of the projects (3-6) will be completed in groups. You will form groups of two people (possibly three, if necessary) to complete these projects. We will allow you to form your own groups. If you are having trouble finding a partner, post a notice to Piazza.

As you are free to choose your partner(s), we will not be sympathetic to complaints at the end of the semester about how your group-mates did not do any work. If you are having problems with your teammate(s), tell us about it sooner rather than later.

You may switch groups between programming projects. All group members should be involved in all major design decisions, and groups should develop a programming plan that can be effectively parallelized. The course projects are hard, so you will want to distribute work between yourself and your teammate.

Programming Languages

Most projects can be programmed in a language of your choice. The only universal requirement is that your projects must compile and run on an unmodified Khoury College Linux machine. Notice the stress on unmodified: if you're relying on libraries or tools that are only available in your environment, then we will not be able to run your code and you will fail the assignment. You are welcome to develop and test code on your home machines, but in the end everything needs to work on the Khoury College Linux machines. If you have any questions about the use of particular languages or libraries, post them to Piazza.


This course will have ten homework assignments reviewing concepts from lecture. Homework assignments are due at 11:59:59pm on the specified date in the schedule. All homeworks, except for the last one, are due on Fridays. Links to the homeworks can be found in the above schedule. Homeworks will be submitted via Gradescope; the easiest way to access the course Gradescope is via the course's Canvas page.

Participation and Attendance

We do not require students to attend class, and we won't be taking attendance. If you need to miss class for any reason, you don't need to tell us beforehand. That said, we like teaching and interacting with students, so please attend class and speak up. We welcome questions and discussion!


Projects (6): 5%, 10%, 15%, 15%, 10%, 15%
Homeworks (10): 3% each

Each project will include a breakdown of how it will be graded. Some projects may include extra credit components that can boost your grade above the maximum score :)

To calculate final grades, we simply sum up the points obtained by each student (the points will sum up to some number x out of 100) and then use the following scale to determine the letter grade: [0-59] F, [60-62] D-, [63-66] D, [67-69] D+, [70-72] C-, [73-76] C, [77-79] C+, [80-82] B-, [83-86] B, [87-89] B+, [90-92] A-, [93-100] A. We do not curve the grades in any way. All fractions will be rounded up.

Requests for Regrading

In this class, we will use the Coaches Challenge to handle requests for regrading. Each student is allotted two (2) challenges each semester. If you want a project or a test to be regraded, you must come to the professors office hours and make a formal challenge specifying (a) the problem or problems you want to be regraded, and (b) for each of these problems, why you think the problem was misgraded. If it turns out that there has been an error in grading, the grade will be corrected, and you get to keep your challenge. However, if the original grade was correct, then you permanently lose your challenge. Once your two challenges are exhausted, you will not be able to request regrades. You may not challenge the use of slip days, or any points lost due to lateness.

Note that, in the case of projects, all group members must have an available challenge in order to contest a grade. If the challenge is successful, then all group members get to keep their challenge. However, if the challenge is unsuccessful, then all group members permanently lose one challenge.

Late Policy

For programming projects, we will use flexible slip days. Each student is given ten (10) slip days for the semester. You may use the slip days on any project or homework during the semester in increments of one day. For example, you can hand in one project ten days late, or one project two days late and two projects four days late. You do not need to ask permission before using slip days; simply turn in your assignment late and the grading scripts will automatically tabulate any slip days you have used.

Slip days will be deducted from each group member's remaining slip days. Keep this stipulation in mind: if one member of a group has zero slip days remaining, then that means the whole group has zero slip days remaining.

After you have used up your slip days, any project handed in late will be marked off using the following formula:

Original_Grade * (1 - ceiling(Seconds_Late / 86400) * 0.2) = Late_Grade

In other words, every day late is 20% off your grade. Being 1 second late is exactly equivalent to being 23 hours and 59 minutes late. Since you will be turning-in your code on the Khoury College machines, their clocks are the benchmark time (so beware clock skew between your desktop and Khoury College if you're thinking about turning-in work seconds before the deadline). My late policy is extremely generous, and therefor we will not be sympathetic to excuses for lateness.

Cheating Policy

It's ok to ask your peers about the concepts, algorithms, or approaches needed to do the assignments. We encourage you to do so; both giving and taking advice will help you to learn. However, what you turn in must be your own, or for projects, your group's own work. Looking at or copying code or homework solutions from other people or the Web is strictly prohibited. In particular, looking at other solutions (e.g., from other groups or students who previously took the course) is a direct violation. Projects must be entirely the work of the students turning them in, i.e. you and your group members. If you have any questions about using a particular resource, ask the course staff or post a question to the class forum.

All students are subject to the Northeastern University's Academic Integrity Policy. Per Khoury College policy, all cases of suspected plagiarism or other academic dishonesty must be referred to the Office of Student Conduct and Conflict Resolution (OSCCR). This may result is deferred suspension, suspension, or expulsion from the university.

Accommodations for Students with Disabilities

If you have a disability-related need for reasonable academic accommodations in this course and have not yet met with a Disability Specialist, please visit www.northeastern.edu/drc and follow the outlined procedure to request services. If the Disability Resource Center has formally approved you for an academic accommodation in this class, please present the instructor with your "Professor Notification Letter" at your earliest convenience, so that we can address your specific needs as early as possible.

Title IX

Title IX makes it clear that violence and harassment based on sex and gender are Civil Rights offenses subject to the same kinds of accountability and the same kinds of support applied to offenses against other protected categories such as race, national origin, etc. If you or someone you know has been harassed or assaulted, you can find the appropriate resources here.