Computer Networking: A Top-Down Approach

Introduction

• Textbook: Computer Networking: A Top-Down Approach, 8th edition by Jim Kurose and Keith Ross, Pearson, 2020.
• Presenter: Yaxiong Xie, University at Buffalo, SUNY.
• Chapter Goal: Provide a big-picture view and introduce terminology. Details covered later.

Overview and Roadmap

• Topics Covered:
  • What is the Internet?
  • What is a protocol?
  • Network edge, core, and performance metrics.
  • Protocol layers and security.

What is the Internet?

• Analogy: Compared to USPS, the Internet is a network that connects billions of computing devices.
• Components:
  • Network Edge: Hosts, access networks, physical media.
  • Network Core: Packet switches (routers, switches), communication links (fiber, copper, radio, satellite).

Internet Protocols

• Protocols govern Internet communication activities.
• Examples:
  • HTTP, SMTP for emails, TCP/UDP for host communication, IP for routers.
• Protocol Layers:
  • Protocols define message formats, order, and actions upon transmission/receipt.
• Organizations: RFC, IETF.

Internet as a Service

• Provides services to applications (e.g., web, streaming, teleconferencing).
• Two types of services:
  • Connectionless (UDP): Faster delivery without connection setup. Suitable for real-time streaming.
  • Connection-oriented (TCP): Reliable, suitable for file transfers.

Network Edge

• Hosts include clients and servers (often in data centers).
• Access networks and physical media: wired, wireless links.

Network Core

• Structure: Mesh of interconnected routers.
• Functions:
  • Forwarding: Local action to move packets through routers.
  • Routing: Global action to find the best path for data transmission.

Packet Switching vs. Circuit Switching

• Packet Switching:
  • Data divided into packets.
  • Shared network resources.
  • Store-and-forward introduces delays.
• Circuit Switching: Dedicated path for duration of a session.

Internet Structure

• Network of Networks: Hosts connect through ISPs.
• Hierarchical Design:
  • Access ISPs connect to larger ISPs.
  • Regional ISPs and content networks.
  • Tier-1 ISPs have global coverage.

Data Transmission and Performance

• Transmission Delay:
  • Time to send all bits into the network.
• Propagation Delay:
  • Time for data to travel across the link.
• Queueing Delay:
  • Time spent waiting in line at routers.
• Throughput:
  • Rate at which data is successfully delivered over a network.
  • Influenced by bottleneck links.

Conclusion

• Real Internet Performance: Uses tools like traceroute to measure delays.
• Packet Loss: Occurs when buffer capacity is exceeded, leading to dropped packets.

This overview provides a foundational understanding of computer networking, emphasizing the structure, function, and protocols that facilitate Internet communication.