1. CS 39006: Computer Networks Lab – Day 1

2. Who’s Who Course Instructors: Teaching Assistants:
Sandip Chakraborty (Office: CSE 311, CSE Main Building) –
K S Rao (Office: SIT Floor, Takshashila Building) –
Teaching Assistants:
Abhijit Mondal (PhD)
Barnoprio Barua (Dual Degree)
Ken Kumar (Dual Degree)
Pradeep R (PhD)
Saikat Biswas (PhD)
Soumyajit Chatterjee (PhD)
Sumitro Bhaumik (PhD)
Course Website:

3. Lab – Dos and Don’ts
Form a group of two and share the group information with Soumyajit by today, latest by January 14, The assignments need to be solved in groups.
You should be there in the lab within 2:10 pm.
Use the Moodle submission page to submit your assignment by the deadline. One of the members from every group can submit. Student enrolment key: STU
If you face any difficulty, feel free to discuss with the instructors and the TAs.
You may discuss with others over Piazza as well. You may use Internet resources.
Zero tolerance against plagiarism. Plagiarized submissions will not be evaluated. Be careful before sharing your codes with others !!!

4. Physical Data Link Network Transport Application
Assignments
8. Implementation of an application layer service
1. Network Traffic Capture and analysis
Physical
Data Link
Network
Transport
Application
2. Network Traffic Capture and analysis – Go deep
3. Socket Programming – Basic client server implementation
5. Implementation of a Transport protocol
4. Socket Programming – Network application parallelization
7. Implementation of Network management and Routing functionalities
6. Implementation of a simple Routing protocol
Some additional assignments may be there depending on the requirements.

5. Lab Evaluation and Grading
Lab assignments will be evaluated by the TAs. You may discussed with the assigned TA and the course instructors in case of any doubts. Marks distribution for each assignments will be shared.
Grading policies:
Assignments: 40%
Lab test 1: 30% (Just before or after the mid-sem)
Lab test 2: 30% (Just before the end-sem)
All assignments do not carry equal weights. The weight distribution among the assignments will be fixed on the day of Lab test 2 based on relative complexity.

6. Coming to Our Context …. Network Protocol Stack
Physical
Data Link
Network
Transport
Application
Software, Kernel
Firmware, Device Driver
Hardware

7. How Application Data Passes Through Different Layers
Physical
Data Link
Network
Transport
Application
HTTP Header
HTTP Data
TCP Header
HTTP Header
HTTP Data
IP Header
TCP Header
HTTP Header
HTTP Data
MAC Header
IP Header
TCP Header
HTTP Header
HTTP Data
PHY Header
MAC Header
IP Header
TCP Header
HTTP Header
HTTP Data
PHY Trailer

8. How do you access a page at www.google.com?
Application Layer: Use DNS to get the IP address of the Google server - DNS returns
Application Layer: Construct an HTTP GET Request – GET /index.html HTTP/1.1 Construct an HTTP packet and forward it to the transport layer

9. How do you access a page at www.google.com?
Transport Layer: Construct the transport layer packet (TCP packet)
Source port: 3324 (port address corresponding to your browser tab)
Destination port: 80 (port for a HTTP server)

10. How do you access a page at www.google.com?
Network Layer: Construct the network layer packet (IP packet)
Source IP: (IP of your machine)
Destination IP: Next hop IP for (use the routing procedure to get this IP)

11. How do you access a page at www.google.com?
Network Layer: Use the routing procedure to find out the next hop IP to reach the Google server at Let this IP be

12. How do you access a page at www.google.com?
Data Link Layer: Construct the data link layer frame from the IP datagram.
How do we get destination MAC address? We need the MAC address corresponding to
Gateway
Local Area Network (LAN)

13. How do you access a page at www.google.com?
Data Link Layer: Use ARP protocol to get the MAC address corresponding to
Gateway
Local Area Network (LAN)

14. Assignment 1: Understand the Packet Structure
Use a packet generation tool: iperf
Use a packet capture and monitoring software: tcpdump and wireshark
Your task would be to capture the packets at different scenarios as explained in the assignment statement and analyze various fields in the headers.
wget
Iperf Client
HTTP Server
iperf Server

15. Assignment 1
Submission deadline: January 18, :00 PM
Prepare a report and submit it to Moodle by the deadline. One member of each group should submit. The report should clearly indicate the name and roll numbers of the group members.