1. CMPE 252A : Computer Networks
Chen Qian
Computer Engineering
UCSC Baskin Engineering
Lecture 1
Slides source: Kurose and Ross, Simon Lam, Katia Obraczka
Introduction

2. Welcome to CE 252A! Class information: When: MWF 09:20-10:25AM.
Where: Engineering
Class Web page:
It is your responsibility to read EVERY sentence on the class website. You also need to check the website at least twice every week to access timely updates to the class

3. About the Instructor Chen Qian. Office: E2 231.
qian "at" ucsc.edu
Office hours: Wednesday, 11am-12pm
Research lab: E2 211

4. Pre-Requisites CMPE 150 or undergrad level networking course.
Graduate level computer programming skills (for project).

5. Teaching Assistants
Shouqian Shi

6. Highly recommend to buy it! It is good based on my experience.
Books
Lecture:
Computer Networking: A Top Down Approach,
by Kurose and Ross
5th, 6th and 7th ed are all good
You are recommended to read the book BEFORE some classes. However the exam questions are ALL related to the material in the slides.
Highly recommend to buy it! It is good based on my experience.

7. Grading Reading reports 15%
Survey study 30% (20 writing + 10 presentation)
Midterm 25%
Course project 30%

8. Student Responsibilities: Academic Integrity
All submitted work must be individual.
OK to have discussions on ideas but turn in your own work.
Survey and Project can be done in a group of at most two students. But each student must submit her/his own report about her/his own contribution.
Ask instructor and TAs if there are any questions.
For more info, go to:

9. Student Responsibilities: Academic Integrity
Academic integrity violations will not be tolerated.
Cheating quizzes.

10. Student Responsibilities
Attendance.
Lectures.
Keep up with material covered in lecture
Readings (chapters in the book).
Sample questions.
Keep up with reading assignments and project.
Turn in the assignments on time!

11. Resources Instructor. TAs. Class Web page.
Lecture notes will be posted before class.
Office hours

12. Student Feedback Feedback is always welcome!
Chance to do it at the end of the quarter.
But you can also do it during the quarter…

13. Lectures The more interactivity, the better! Ask questions!
Or answer my questions.
Lecture notes:
Will be posted on-line before class.
But…

14. Project You may choose one of the following. 1. Recommended Project
2. Self-defined Project
Any topic related to networking
Need approval from me to continue
Detailed guideline:
01.courses.soe.ucsc.edu/node/5

15. Reading reports
There are around 15 research papers for the instructor/TA to present in total. You should submit no fewer than 8 reading reports.
Each report will be graded as a check- (1pt), check (1.5pt), or check+ (2pt). 
You may submit more but we only count the 8 reports with highest grades. 
Introduction

16. Survey paper
You are allowed to work in a group of two on the survey paper. Among the 30 points of the survey paper, 20 will be based on the writing and 10 will be based on your presentation and Q&A.
Detailed guideline:
Introduction

17. Midterm Exam November 2nd .
Close book, can bring one-side 8.5"x11" note
Introduction

18. Assignment late submission policy
20% deduction for each day late.

19. Submission site Reading reports: canvas Survey: canvas Project: gitlab
Introduction

20. Administrative Info Communication: E-mail preferred.
Send to both instructor AND TAs.

21. Course Outline Basic Knowledge of computer networking
Application layer
Transport layer
Network layer
Link layer
Advanced topics
Software defined networks
Cloud and data center networks
Wireless and mobile networks
Internet of things
Network security
Edge computing

22. My background
PhD in Computer Science (2013), University of Texas at Austin
Advisor: Simon Lam – researcher of the chapter for “The Link Layer” pp 511 22

23. BTW…. Simon Lam’s PhD advisor was Leonard Kleinrock, Professor at UCLA
researcher of the chapter for “Chapter 1”
Introduction

24. My Research Network algorithms, protocols, and systems
Routing, switching, management, etc.
Current focus: Internet of Things, Software Defined Networking, and Network Security
Introduction

25. Networks: overview 1.1 Terms of a network 1.2 network edge
end systems, access networks, links
1.3 network core
packet switching, circuit switching, network structure
1.4 protocol layers
Introduction 25

26. What are the components of a computer (communication) network?
Links, nodes, and
Terminals/hosts/end systems/servers
What’s the difference between “nodes” and “hosts”?

27. Nodes and hosts
Source: K. Salah Module 3.4

28. What are the performance metrics we care about?
Latency
Bandwidth/throughput
Bandwidth: the max throughput a communication link can provide
Scalability
When size is large, will there be a problem?
Memory, cpu, latency, etc.
Reliability
When some nodes/hosts fail
Security
Financial cost
Introduction

29. Any network design is a trade-off
What are the trade-offs of the following designs:
Encryption/decryption
Redundancy
Peer-to-peer networks
Introduction

30. What’s the Internet: “Nuts and Bolts” View
Internet: “network of networks”
hierarchical
Institutional network
Mobile network
Global ISP
Home network
Regional ISP

31. What’s the Internet: “Service” View
Communication Infrastructure
enables distributed applications:
Web, VoIP, , games, e-commerce, file sharing
Communication services provided to apps:
reliable data delivery from source to destination
“best effort” (unreliable) data delivery
Institutional network
Mobile network
Global ISP
Home network
Regional ISP

32. A closer look at network structure:
network edge:
hosts: clients and servers
servers often in data centers
mobile network
global ISP
regional ISP
home
network
institutional
access networks, physical media: wired, wireless communication links
network core:
interconnected routers
network of networks

33. The network core
packet-switching: hosts break application-layer messages into packets
forward packets from one router to the next, across links on path from source to destination
each packet transmitted at full link capacity

34. Packet Switching: queueing delay, loss
R = 100 Mb/s D
R = 1.5 Mb/s B E
queue of packets
waiting for output link
queuing and loss:
If arrival rate (in bits) to link exceeds transmission rate of link for a period of time:
packets will queue, wait to be transmitted on link
packets can be dropped (lost) if memory (buffer) fills up

35. Internet protocol stack
application: supporting network applications
FTP, SMTP, HTTP
transport: process-process data transfer
TCP, UDP
network: routing of datagrams from source to destination
IP, routing protocols
link: data transfer between neighboring network elements
Ethernet, (WiFi), PPP
physical: bits “on the wire”
application
transport
network
link
physical

36. Encapsulation source destination application transport network link
message M
application
transport
network
link
physical
segment Ht M Ht
datagram Ht Hn M Hn
frame Ht Hn Hl M
link
physical
switch
destination
network
link
physical Ht Hn M Ht Hn Hl M M
application
transport
network
link
physical Ht Hn M Ht M Ht Hn M
router Ht Hn Hl M

37. Next class
Please read Chapter 2 of the textbook BEFORE Class 37