Tutor knowledgeComputer NetworksLLM Files / Knowledge Files378 KB
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Fernando Kuipers, Otto Visser
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Topics for today:
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Image /page/2/Picture/0 description: The image shows a logo with the letters "VSSD" in a bold, sans-serif font. The letters are arranged horizontally, with the "V" slightly larger than the "SSD". To the left of the "VSSD", there is a circular target symbol with two horizontal lines intersecting at the center. Below the "VSSD", there is the tagline "For your interests!" in a smaller, italicized font. The entire logo is in a single color, which appears to be a shade of orange, and it is set against a light background.
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Image /page/3/Picture/1 description: The image shows a logo with the letters "VSSD" in orange, with the words "For your interests!" underneath. To the left of the letters is an orange circle with two lines crossing in the center, resembling a target.
Image /page/3/Picture/7 description: A wide shot shows a crowd of people standing on the steps in front of a large, cone-shaped building. The people are holding signs and banners, and they appear to be protesting or demonstrating. The banner in the foreground says "Delft" on it. The building in the background is a modern structure with a pointed roof. The sky is overcast, and the overall tone of the image is serious.
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Image /page/4/Picture/1 description: The image shows a logo with the letters "VSSD" in a stylized orange font. The letters are partially encircled by an orange target symbol. Below the letters, in a smaller font, is the phrase "For your interests!" The background is a light beige color.
Image /page/4/Picture/10 description: A group of people are standing on the steps in front of a large, cone-shaped building. The people are holding signs and banners, and they appear to be protesting or demonstrating. The building in the background is a modern structure with a unique design. The sky is overcast, and the overall scene suggests a public gathering or event.
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Image /page/5/Picture/5 description: The image shows a logo with the letters "VSSD" in a bold, orange font. The letters are slightly overlapping. To the left of the letters is an orange circle with a crosshair design inside. Below the letters is the phrase "For your interests!" in a smaller, sans-serif font, also in orange. The background is a light beige color.
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Image /page/6/Picture/1 description: The image shows a logo for VSSD. The logo is orange and consists of the letters "VSSD" in a bold, sans-serif font. To the left of the letters is a circle with two lines crossing through it, resembling a target. Below the letters is the tagline "For your interests!" in a smaller, italicized font. The background is a light beige color.
08:30 picket lines and banner making 11:30/12:00 walkout and free fries at pulse 12:30 speakers program at pulse walking to the park near the station 15:00 closing activities
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(watch out: mandatory presence can sometime still be asked)
Image /page/7/Picture/5 description: A group of people are walking on a sidewalk. The people are dressed in casual clothing, and they appear to be walking in the same direction. The sidewalk is made of brick, and there is grass on the side of the sidewalk. There is a tree on the left side of the image.
Image /page/7/Picture/6 description: The image shows a logo with the letters "VSSD" in orange, next to a circle with two lines crossing through it, also in orange. Below the letters, in smaller orange font, are the words "For your interests!" The background is a light beige color.
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Image /page/8/Picture/0 description: The image shows a logo with the letters "VSSD" in orange. To the left of the letters is an orange circle with two lines crossing through it, resembling a target. Below the letters, in a smaller font, is the text "For your interests!" also in orange. The background is a light beige color.
Image /page/8/Picture/3 description: The image shows a QR code with a WhatsApp logo in the center. An arrow points from the left side of the image to the QR code. The text "Keep updated!!!" is on the left side of the image.
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There are no new recordings this year.
There are recordings from an earlier year available, which are close enough to what we do this year.
Main differences: change of staff and we cut a few details here and there. Some parts are updated and others might receive more/less focus.
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Lecture-related questions:
https://answers.ewi.tudelft.nl (tag: cse1405)
Email: cn-cs-ewi@tudelft.nl
Questions on programming assignments + tutorials: Enqueue during the shared labs (Monday, Wednesday)
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| ACTAL AP | ||||||
|---|---|---|---|---|---|---|
| Week | Mo | Tu | Wed | —— | <u>יטריקט ו</u> | |
| 4.1 | L1 | L2 | Introduction | |||
| 4.2 | L3 | L <sub>4</sub> | Data Link Layer | |||
| L5 |
Follow presentation of new material + ask questions
Solve quizzes/exercises
Discuss tutorial solutions
Contribute to Q&A sessions
in the lecture
beforehand
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Image /page/14/Figure/1 description: This image is a diagram of a course schedule. It starts with "Lecture 1" on April 24 and ends with "Lecture 15" on June 20. The diagram includes lectures and tutorials, with dates and topics listed for each. For example, "Lecture 2" is on April 25 and covers "Data Link Layer", and "Tutorial 1" is on May 9. There are also notes and programming exercises indicated throughout the schedule. The word "CONFUUSION" is written in a red bubble.
| Task | Depends on | To be completed before |
|---|---|---|
| Notes Errors | Lecture 1 (April 24) | Lecture 4 (May 2) |
| Notes Cryptography | nothing | Lecture 12 (June 12) |
| Tutorial 1 | Notes Errors | Lecture 6 (May 9) |
| Tutorial 2 | Notes Errors | Lecture 6 (May 9) |
| Tutorial 3 | Lecture 3 (May 1) | Lecture 8 (May 16) |
| Tutorial 4 | Lecture 8 (May 16) | Lecture 9 (May 30) |
| Tutorial 5 | Lecture 10 (May 31) | Lecture 11 (June 6) |
| Tutorial 6 | Lecture 11** (June 6) | Lecture 13 (June 13) |
| Tutorial 7 | Notes Cryptography | Lecture 15 (June 20) |
| Week | Mo | Tu | Wed | Thu | Fri | Topics | ||
|---|---|---|---|---|---|---|---|---|
| 4.1 | L1 | L2 | Introduction | |||||
| 4.2 | L3 | L4 | Data Link Layer | |||||
| 4.3 | L5 | L6 | MAC Sublayer | |||||
| 4.4 | L7 | L8 |
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· https://skills.ewi.tudelft.nl/edition/946
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For each chapter, we provide
Gives indication of what to focus on
Can be read:
Not every exam question has to match a question type listed under "Question Types to Expect in the Exam"
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Image /page/17/Picture/0 description: The image shows the word "Book" in a simple, sans-serif font. The letters are black and the background is white.
6th Edition of Computer Networks
By Tanenbaum, Wetherell, Feamster (Edition 6)
Image /page/17/Picture/3 description: The image is a book cover for "Computer Networks" by Tanenbaum, Feamster, and Wetherall, Sixth Edition, Global Edition. The cover features a cityscape at night with binary code overlaying the buildings and street. The title and authors' names are prominently displayed in white text. The publisher's logo is in the bottom left corner.
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| Topic | Edition 6 |
|---|---|
| Introduction<br>(Lecture 1) | 1.5 (excluding 1.5.4),<br>1.6 |
| Data link Layer<br>(Lecture 2+3) | 3.1, 3.3, 3.4 |
| MAC-Sublayer<br>(Lecture 4+5+6) | 4.1, 4.2 (excluding 4.2.4),<br>4.3 (up to and including 4.3.3)<br>4.4, 4.7 |
| Network Layer<br>(Lecture 7+8) | 5.1, 5.2.4, 5.2.5, 5.2.6<br>5.3, 5.5, 5.7 (excluding 5.7.8) |
| Transport Layer<br>(Lecture 9+10+11) | 6.1, 6.2, 6.3 (excluding 6.3.3),<br>6.4.1, 6.5 (excluding 6.5.7, 6.5.9,6.5.11) |
| Application Layer<br>(Lecture 11+12+13) | 7.1 (excluding 7.1.7, 7.1.8)<br>7.2, 7.3 (excluding 7.3.5)<br>7.4, 7.5 (excluding 7.5.2) |
On Brightspace: Content->Course Information->Book
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| Task | Depends on | To be completed before |
|---|---|---|
| Notes Errors | Lecture 1 (April 22) | Lecture 4 (May 1) |
| Notes Cryptography | nothing | Lecture 12 (June 5) |
| Tutorial 1 | Notes Errors | Lecture 6 (May 8) |
| Tutorial 2 | Notes Errors, Lecture 2 (April 24) | Lecture 6 (May 8) |
| Tutorial 3 | Lecture 3 (April 29) | Lecture 8 (May 15) |
| Tutorial 4 | Lecture 8 (May 13) | Lecture 10 (May 29) |
| Tutorial 5 | Lecture 10 (May 29) | Lecture 12 (June 5) |
| Tutorial 6 | Lecture 12 (June 5) | Lecture 14 (June 12) |
| Tutorial 7 | Notes Cryptography | Lecture 15 (June 17) |
If you do not complete these tasks before these lectures, you might not be able to follow that lecture!
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2 Tasks (error detection/correction; cryptography) Reading material & videos (the provided document has links to videos) Schedule roughly 4 hours of time for each
Topics with high variation in background, with a number of examples Also, topics with cool (youtube) videos
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| Task | Depends on | To be completed before |
|---|---|---|
| Notes Errors | Lecture 1 (April 22) | Lecture 4 (May 1) |
| Notes Cryptography | nothing | Lecture 12 (June 5) |
You can start today!
"Best" time for second task: late May/early June (but you can do it now)
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7 Tutorials
Exercises (in general: apply algorithms to toy examples)
Each 1 hour (based on previous years)
Can be done in groups or individually
Ask TAs questions in shared lab
Solutions will be discussed + published later on Brightspace
Deeper insights on algorithms
Exercises might just be quite similar to exam exercises
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| Tutorial 1 | Notes Errors | Lecture 6 (May 8) |
|---|---|---|
| Tutorial 2 | Notes Errors, Lecture 2 (April 24) | Lecture 6 (May 8) |
| Tutorial 3 | Lecture 3 (April 29) | Lecture 8 (May 15) |
| Tutorial 4 | Lecture 8 (May 13) | Lecture 10 (May 29) |
| Tutorial 5 | Lecture 10 (May 29) | Lecture 12 (June 5) |
| Tutorial 6 | Lecture 12 (June 5) | Lecture 14 (June 12) |
| Tutorial 7 | Notes Cryptography | Lecture 15 (June 17) |
First 2 tutorials: depend on self-study assignment 1
Discuss in week 3 with self-study "due" in week 2
Afterwards, 1 tutorial per week
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*) Not on holidays
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On the long term: starting next year, it will be assumed that you can implement algorithms you learn about => basis for actual tasks
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Lec: Lecture Self: Self-Study assignments Tut: Tutorial Lab: Lab/Programming
The student can describe the principles of layered architectures, in particular the functions and purposes of all layers for the OSI reference model (Lec)
The student can describe the core algorithms of each layer and provide arguments why these algorithms fulfill the function of the respective layer (Lec, Self)
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Image /page/28/Picture/1 description: The image shows a cartoon drawing of a woman sitting at a desk using a laptop, a cloud with the word "internet" written inside, a red arrow pointing down from the cloud, and a boy talking on a cell phone. There are also two paper airplanes flying around the cloud. The text "How does the internet work?" is at the bottom of the image.
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Image /page/29/Picture/1 description: This image shows a newspaper article from the Daily Mail, dated Tuesday, December 5, 2000. The headline reads, "Internet 'may be just a passing fad as millions give up on it'." The article is written by James Chapman, Science Correspondent. A picture of a computer is on the right side of the article. The article states that the internet may be only a passing fad for many users, according to a report. It also mentions a net loss of two million Britons who have logged off the Internet.
according to a report.
Researchers found that millions were turning their back on the world wide web, frustrated by its limitations and unwilling to pay tugh access charges.
They say that e-moil, far from replacing other forms of communicainformation.
and a from the Virtual Bottely.
woodgar, director of the society, said. We are often presented with a picture of tairgeoning Internet one, but there is evidence atready of drop-off and saturation among users
"Demagers' use of the Internet has declined. They were energieed by what you can do on the Net hut they tieve been through all that and then realised there is more to life in the west world and mone back to it.
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A major part of all the software you will be developing is networked:
• client/server, cloud, mobile, cars, and even fridges
Understand what is wrong with your local networks Maybe fix it and/or optimize it Be aware who can see which information you share Make an informed decision about how you act online
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Software developer Cloud engineer Network engineer Computer systems analyst Penetration tester Anything related to streaming,
self-driving cars, online gaming
Why care how it works?
Jobs related to networks
Image /page/31/Picture/4 description: The image shows the logo for Core Security, a HelpSystems Company. The logo is white text on a black background. The word "CORE" is at the top, with a globe graphic inside the "O". Below that is the word "SECURITY" in a smaller font. Underneath that is the text "A HelpSystems Company" in an even smaller font.
Image /page/31/Picture/5 description: A person is sitting in front of a computer screen playing a video game. The person is wearing a headset and is using a keyboard and mouse to control the game. The game appears to be a multiplayer online battle arena (MOBA) game, with a top-down perspective and colorful graphics. The person is focused on the screen and appears to be enjoying the game.
Image /page/31/Picture/6 description: A close-up shot depicts a fair-skinned hand holding a red pen. The pen is positioned diagonally across the frame, with the tip pointing towards the upper right corner. The hand is gripping the pen firmly, with the thumb resting on the pen's clicker. The background is a plain white, which helps to emphasize the hand and the pen.
What my friends think I do
Image /page/31/Picture/10 description: A man with a beard and a unicorn horn on his head is holding a pinwheel and a pink balloon. He is wearing a white t-shirt that is covered in paint. He has a surprised expression on his face. The background is purple.
What hackers think I do
Image /page/31/Picture/12 description: A man in a suit is opening his shirt to reveal a blue shirt underneath and a red cape. The sun is shining behind him, and he is standing in front of a cityscape.
What I think I do
Image /page/31/Picture/14 description: A man is sitting at a desk in front of a computer. He is typing on the keyboard. The computer screen is displaying a program with a lot of text and data. The man is wearing a gray shirt. The desk is white. The background is a plain white wall.
What I actually do
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Image /page/32/Figure/1 description: The image shows a cartoon hospital with a speech bubble coming from it. The speech bubble says, "Can't give you any data due to GDPR."
Distributed/Federated Machine Learning: Data is not shared but models are shared and combined
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Algorithm -> protocol Function signature-> service
Do you know any protocols? Which services do they provide?
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Computer scientists like layers Why? They provide levels of abstraction Each layer provides services But only to layer above
Image /page/34/Figure/2 description: The image shows three blue rectangles stacked vertically, labeled "Layer 3", "Layer 2", and "Layer 1" from top to bottom. Curved arrows connect Layer 3 to Layer 2 and Layer 2 to Layer 1, indicating interaction between adjacent layers. To the right, a gray rectangle contains the text "No direct interaction between Layer 1 and Layer 3".
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Same layers on multiple machines Lowest one does actual communication
Image /page/35/Figure/2 description: The image shows two machines, Machine 1 and Machine 2, each with three layers stacked on top of each other. The layers are labeled as Layer 1, Layer 2, and Layer 3 from bottom to top. There are curved arrows connecting the layers within each machine, indicating communication or interaction between them. Additionally, there is a double-headed arrow connecting Layer 1 of Machine 1 to Layer 1 of Machine 2, suggesting direct communication or data transfer between these layers.
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Image /page/36/Figure/1 description: The image shows a communication flow between two parties using emojis and scrolls. On the left side, a king emoji sends a message bubble saying "I want a treaty." down to a scholar emoji, which then sends a scroll labeled "To: QK I want a treaty." down to a bird carrying a scroll. The bird flies to the right, delivering the scroll to another bird. On the right side, the bird delivers the scroll to a winter hat emoji, which sends a message up to a scholar emoji giving a thumbs up. The scholar emoji sends a scroll labeled "To: QK I want a treaty." up to a king emoji with a crown askew, who also sends a message bubble saying "I want a treaty."
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Image /page/37/Figure/1 description: The image shows a diagram of communication between two locations, A and B. At location A, a person is thinking about rabbits and sends a message to location B. At location B, a philosopher receives the message and translates it into French. The message is then sent to a translator at location A, who translates it into Dutch. The Dutch message is then sent to a secretary at location B, who sends it to a fax machine at location A. The fax machine then sends the message back to location B.
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Image /page/38/Figure/1 description: The image shows a diagram of two layers communicating with each other. On the left side, there is a box labeled "Layer k" with an arrow pointing up to "Layer k + 1" and an arrow pointing down to "Layer k - 1". There is also a text "Service provided by layer k" above the box. On the right side, there is a similar box labeled "Layer k" with an arrow pointing up to "Layer k + 1" and an arrow pointing down to "Layer k - 1". A dashed line labeled "Protocol" connects the two "Layer k" boxes.
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Send one bit via a physical medium ("link")
Image /page/39/Picture/2 description: The image shows a cross-section of a blue fiber optic cable. The cable has multiple layers of protection, including a blue outer jacket, a green layer, and a white layer. Inside the cable are several colored optical fibers, including orange, green, blue, and yellow. The fibers are arranged in a circular pattern, and each fiber is surrounded by a clear protective coating.
Image /page/39/Picture/3 description: The image shows a blue ethernet cable on the left and a black TP-Link AC1750 router on the right. The ethernet cable has a clear plastic connector. The router has three antennas and several green indicator lights on the front.
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Send a sequence of bits over a link reliably
Image /page/40/Picture/2 description: The image shows a smartphone on the left, an arrow in the middle, and a router on the right. The arrow points from the smartphone to the router. Above the arrow is the text "10101110 -> 10101100", and below the arrow is the text "1101001 -> 11010". The digits in red are being removed.
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Send data from one computer in a network to another (examples: home network, company network, Internet)
Image /page/41/Figure/2 description: The image shows a network diagram with a source, destination, and routers. The source is connected to a router, which is connected to two other routers. One of these routers is connected to the destination. The routers are connected in a triangular pattern.
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Image /page/42/Picture/2 description: The image shows a diagram of a communication system. On the left side of the image, there is a box labeled "Source". On the right side of the image, there is a box labeled "Destination". The source and destination are connected by a black box.
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Image /page/43/Picture/2 description: The image shows six different logos. From left to right, the first logo is a blue bird holding a yellow envelope. The second logo is a blue rounded square with a white "m" inside. The third logo is a blue speech bubble with a white lightning bolt inside. The fourth logo is a white mouse head with black eyes and nose. The fifth logo is a red and orange fox curled around a blue globe. The sixth logo is a black circle with a white gear inside.
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Image /page/44/Figure/1 description: The image shows the acronym "OSI" followed by an equals sign and the words "Open Systems Interconnections".
5 Application
| 4 | Transport |
|---|---|
| 3 | Network |
| 2 | Data link |
| 1 | Physical |
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Image /page/45/Figure/1 description: The image shows the OSI (Open Systems Interconnections) model, which is a conceptual framework for understanding how different network devices communicate with each other. The model is divided into seven layers, each of which is responsible for a specific set of tasks. From top to bottom, the layers are: Application, Presentation, Session, Transport, Network, Data link, and Physical. An arrow points from the Presentation and Session layers to a blue box that says "Essentially no dedicated protocols".
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Layer
Image /page/46/Figure/2 description: The image shows a diagram of the seven layers of the OSI model, with two hosts (A and B) communicating with each other. The layers are, from top to bottom: Application (layer 7), Presentation (layer 6), Session (layer 5), Transport (layer 4), Network (layer 3), Data link (layer 2), and Physical (layer 1). The diagram also shows the protocols used at each layer, such as Application protocol, Presentation protocol, Session protocol, and Transport protocol. The communication subnet boundary is shown between the Transport and Network layers. The internal subnet protocol is used for communication between the Network, Data link, and Physical layers. The diagram also shows the network layer host-router protocol, data link layer host-router protocol, and physical layer host-router protocol.
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Image /page/47/Figure/0 description: The image shows the text "Message Host A (source, sender)" in large, bold font. Below the text is the phrase "User A Input" next to a blue square.
Image /page/47/Figure/1 description: The image shows a diagram of the OSI model, which is a conceptual model that characterizes and standardizes the communication functions of a telecommunication or computing system without regard to its underlying internal structure and technology. The model is divided into seven layers, each of which performs a specific function. From top to bottom, the layers are: Application (7), Transport (4), Network (3), Data link (2), and Physical (1). The diagram also shows the flow of data between the layers, as well as the encapsulation of data at each layer. The bottom layer is labeled "Host A".
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Image /page/48/Figure/1 description: The image shows a diagram of a network stack with three layers: Network, Data link, and Physical Router. Arrows indicate the flow of data between the layers. There are data packets shown on either side of the layers.
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Image /page/49/Figure/1 description: The image shows a diagram of the OSI model with the layers labeled as Application, Transport, Network, Data link, and Physical. The diagram also shows the flow of data from User B to Host A. The data is represented as a blue block, and as it moves down the layers of the OSI model, additional information is added to the data in the form of green and peach blocks. The arrow indicates the direction of data flow from User B to Host A.
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Image /page/50/Figure/1 description: The image shows a comparison between the OSI model and the TCP/IP model. The OSI model has 7 layers: Physical, Data link, Network, Transport, Session, Presentation, and Application. The TCP/IP model has 4 layers: Host-to-network, Internet, Transport, and Application. The Presentation and Session layers are not present in the TCP/IP model.
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OSI
Application
Image /page/51/Figure/3 description: The image shows a diagram of the four layers of the TCP/IP model. From top to bottom, the layers are: Transport (layer 4), Network (layer 3), Data link (layer 2), and Physical (layer 1).
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Fernando Kuipers, Otto Visser
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OSI
Application
Transport 4 3 Network 2 Data link Physical 1
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Image /page/54/Figure/1 description: This image shows the OSI model layer 7, which is the application layer. The application layer provides application-specific functionality.
Image /page/54/Figure/2 description: The image shows a diagram of the four layers of the TCP/IP model. From top to bottom, the layers are: Transport, Network, Data link, and Physical. The Transport layer sends data stream reliably (or not) over multiple links. The Network layer sends data over multiple links (source -> destination). The Data link layer reliably transmits data over a link. The Physical layer transmits one bit over a "link" (cable, wireless).
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Image /page/55/Figure/1 description: The image shows a network diagram with a source, destination, and several routers. The source and destination are represented as gray cubes, while the routers are represented as gray rectangular boxes with antennas. The routers are connected to each other and to the source and destination via black lines. The word "Source" is written below the source cube, the word "Destination" is written below the destination cube, and the word "Router" is written below one of the routers. A red circle surrounds the source cube and the router it is connected to.
How does the data get from source to first router reliably? (We will worry about the rest once we have this solved)
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Error control: Deal with bit flips and lost data
Channel allocation (contention): Deciding how to share medium
Image /page/56/Figure/3 description: The image shows a laptop and a smartphone sending data to a router. The laptop sends the data '10101110 -> 10101100' to the router, while the smartphone sends the data '1101001 -> 11010' to the router. The data sent by the laptop is longer than the data sent by the smartphone. The router has three antennas and several indicator lights on the front.
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Physical layer sends bits
Name of the unit including addional bits: Frame
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Image /page/58/Figure/1 description: The image shows a diagram of a data packet structure. The packet is divided into three sections: Header, Data (aka: Payload), and Trailer. The Header is described as containing information such as sender, receiver, and version. The Trailer is described as containing error detection/correction bits.
Header and trailer: fixed length and structure Data: variable length (with maximum and minimum)
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Image /page/59/Figure/0 description: The image shows the structure of an Ethernet frame. The frame consists of several fields, including Preamble (8 bytes), Destination address (6 bytes), Source address (6 bytes), Type (2 bytes), Data (0-1500 bytes), Pad (0-46 bytes), and CRC (4 bytes). The Preamble, Destination address, Source address, and Type fields are grouped together as the Header. The CRC field is labeled as the Trailer.
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State at party S
Sent to R: 5B Received from R: 0B
Time
Sent to R: 5B Received from R: 1B
Sent to R: 9B Received from R: 1B
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Part 1 of 10 — loading the next…
| L <sub>6</sub> |
| <b>MAC Sublayer</b> |
| L7 | L <sub>8</sub> | Network layer |
| 4.5 |
| 4.6 | L9 | L <sub>10</sub> | <b>Transport Layer</b> |
| 4.7 | L <sub>11</sub> | L <sub>12</sub> | <b>Application Layer</b> |
| 4.8 | L <sub>13</sub> | L <sub>14</sub> | Security |
| 4.9 | <b>L15</b> | Recap |
| Network layer |
| 4.5 |
| 4.6 | L9 | Transport Layer |
| 4.7 | L10 | L11 | Application Layer |
| 4.8 | L12 | L13 | Security |
| 4.9 | L14 | L15 |