1COMP 3331/9331:
Computer Networks and Applications
Recap
Term 3, 2023
2Recap Week 1-10
Covered networking using a top-adown approach: from the
applications to transport to networking to data link layer
q end-system applications,
end-end transport
q network core: routing,
hooking nets together
q link-level protocols, e.g.,
Ethernet
q other stuff: wireless networks
3What you have accomplished
• Comprehensive overview of the entire protocol stack
with a particular focus on the Internet
• Key principles
• Layering, scale, hierarchy, etc.
• Key design issues
• Application architectures, reliability, congestion control,
routing, medium access, etc.
• Hands-on practical laboratory experiments using
several diagnostic tools, Wireshark and ns-2
• Developed a “real-world” networking application
Key topics in Week-1: Network Introduction
Textbook Chapter: Chap 1: 1.1-1.5
• Internet as a network of networks
• The protocol stack and layering principle
• Edge vs. Core
• Loss, delay and throughput
• Packet switching vs. Circuit switching
4
Key topics in Weeks 2-3: Application Layer
Textbook Chapter: Chap2: 2.1, 2.2,2.4,2.5,2.6,2.7
• HTTP
• Email
• DNS
• P2P
• Video Streaming
• CDN
• Socket Programming Overview
5
Key topics in Weeks 4-5: Transport Layer
Textbook Chapter: Chap 3: 3.1 - 3.7
• Multiplexing and demultiplexing
• Reliable data transfer
• Flow control
• Congestion control
• TCP
• UDP
6
Key topics in Weeks 7-8: Network Layer
Textbook Chapters: Chap 4: 4.1, 4.3 | Chap 5: 5.1, 5.2, 5.6
• Forwarding vs. Routing
• IP addressing, subnets, CIDR, longest prefix matching
• IP packet structure (header fields)
• Checksum
• IP fragmentation and reassembly
• DHCP overview
• NAT
• Routing: Link state, distance vector
• ICMP overview
7
Key topics in Week-9: Data Link Layer
Textbook Chapter: Chap 6: 6.1 – 6.4, 6.7
• Error detection and correction using Parity, CRC
• The concept of multiple access and medium access
control (MAC)
• MAC addressing
• MAC protocols: TDMA, FDMA, ALOHA
(Slotted vs. Pure), CSMA, etc.
• CSMA for wired networks (Ethernet) and
Collision Detection
• Switching
8
Key topics in Week-10: Wireless Networks
Textbook Chapter: Chap 7: 7.1 – 7.3
• Wireless link characteristics
• 802.11 (WiFi)
• Hidden nodes (a.k.a. hidden terminals)
• Exposed nodes (a.k.a. exposed terminals)
• RTS, CTS, ACK
• CSMA/CA
• Random backoff
• Rate adaptation with dynamic coding and modulation
• Frame addressing
• Association: passive scanning vs, active scanning
9
10
What’s next?
• COMP 9333: Advanced Computer Networks
(refreshed)
• COMP 9334: System Capacity and Planning
• COMP 4336/9336: Mobile Data Networks
• COMP 6441/9441: Security Engineering and
Cybersecurity ( + other security courses)
• COMP4337/9337: Wireless Network Security
• COMP6337: IoT Experimental Design Studio
• Undergraduate/Postgraduate Projects and Thesis
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