Learning Objectives

After successfully completing this section, you should be able to

  1. explain what computer networks are.
  2. describe the Internet and the World Wide Web.
  3. show how computer networks, the Internet, and the Web are related.

Learning Tasks

Required:

  1. Watch the slideshow prepared for this section.
  2. Study the following sections of the textbook:

1.1 What is the Internet?
1.2 The Network Edge
1.3 The Network Core
1.4 Delay, Loss, and Throughput in Packet-Switched Networks

Suggested:

  1. Read “A Little History of the World Wide Web” found on the WWW Consortium site and “Brief History of the Internet” on the Internet Society site.
  2. Write an HTML document containing a list of networking terms and definitions. Try to include as many terms as you can find from the textbook or online sources. For information on basic HTML, see the W3Schools’ HTML Tutorial.
  3. If possible, visit an organization that has a Local or Wide Area Network. List the devices or components of the network(s) and describe the operating systems and other software used.
  4. Visit the Internet Engineering Task Force and World Wide Web Consortium sites to gain an understanding of the roles and activities of these groups.
  5. Read Section 1.6, Networks Under Attack, in the text, although network security is not covered by the course.

Terms and Topics

Section 1 – Overview of Computer Networks

The Internet
computer networks
the World Wide Web
communication links
packet switches
transmission rate
packets
path, route, and routers
Internet service providers
Protocol and network protocols
Transmission control protocol (TCP)
Internet protocol (IP)
Internet standards
IETF and RFCs
Distributed applications
Application Programming Interface (API)
The network edge
Hosts and end systems
Clients
servers
Access networks
Edge router
DSL
Cable Internet access
Fiber to the home (FTTH)
Dial-up
Satellite
Ethernet
WiFi

Wide-area wireless access
3G network
LTE network
Physical media
Guided media
Unguided media
Unshielded twisted pair (UTP)
Coaxial cable
Fiber optics
Terrestrial radio channels
Satellite radio channels
Geostationary satellite
Low-earth orbiting (LEO) satellite
The network core
Packet switches
Link-layer switches
Store-and-forward transmission
Messages and message switching
Output buffer / output queue
Queuing delays
Packet loss
Forwarding table (of routers)
Routing protocols
Circuit and circuit switching
End-to-end connection

Multiplexing in circuit-switched networks
TDM (Time Division Multiplexing)
FDM (Frequency Division Multiplexing)
Bandwidth
Silent periods (of circuit)
Global transit ISP
Regional ISP
Tier-1 ISP
Internet Exchange Point (IXP)
Content Provider Networks (CDNs)
Delay, loss, and throughput in packet-switched networks
Types of delay
Nodal processing delay
Queuing delay
Transmission delay
Propagation delay
Total nodal delay
Queuing delay and packet loss
Traffic intensity
Packet drop and packet loss
Instantaneous throughput
Average throughput
Bottleneck link

Leading Questions

  1. What is a computer network? When, where, and by whom was the first computer network invented?
  2. What are the different types of computer networks? How are they classified? Describe the distinctions among them.
  3. How many layers are there in the ISO network model? What are they? What does each layer do?
  4. How many layers are there in the Internet protocol stack?
  5. What is circuit switching, packet switching, message switching, multiplexing, and routing respectively? What are the differences between circuit, packet, and message switching?
  6. What kinds of delays may occur in a computer network? How can each delay be calculated?
  7. How are homes, institutions, and mobile users connected to the Internet? What components are needed to set up Internet connections?
  8. What devices are needed to build a simple computer network?
  9. What is the hierarchy of Internet Service Providers (ISPs)? Describe each of the following: NAP, regional ISP, local ISP, and end users.
  10. In the context of computer networking, what are clients and what are servers? What is a connection-oriented service? What is a connectionless service?
  11. What organization is responsible for computer networking standards? What standards are in place?
  12. What organization is responsible for Internet standards? What standards are being used today?
  13. What organization is responsible for World Wide Web standards? What standards are being used today?
  14. What are IP addresses? How are IP addresses classified? What are the classes of computer networks? What IP addresses are reserved, and for what purposes?
  15. What are non-routable IP Addresses, domain names, and host names?
  16. How are host names mapped to IP addresses? What is DNS, and how does it work?
  17. What are firewalls and proxy servers, and why do we need them?