Chapter 2
Network Topologies, Architectures,
and the OSI Model
In this chapter we present several fundamental networking concepts. We begin with an
overview of network topologies, giving examples of the two most general designs on
which most topologies are based: point-to-point and broadcast. Next, we examine the con-
cept of network architecture. As part of this discussion we introduce the idea of “layering”
and present the Open Systems Interconnect (OSI) networking model as an example of lay-
ered architecture. We conclude the chapter with an introduction to TCP/IP and show how
it relates to the OSI model. An outline of the material we discuss follows:
• Concept of Network Topologies (Questions 1–2)
• Point-to-Point Networks: Star, Loop, Tree (Questions 3–9)
• Broadcast Networks: Bus, Ring, Satellite (Questions 10–22)
• Multidrop Networks (Question 23)
• Circuit- and Packet-Switched Networks (Questions 24–32)
• Network Architectures (Questions 33–34)
• The OSI Model (Questions 35–41)
• Connection-Oriented and Connectionless Services (Questions 42–46)
• The TCP/IP Model (Questions 47–52)
1. What is a network topology?
A network topology is the basic design of a computer network. It is very much like a
road map. It details how key network components such as nodes and links are intercon-
nected. A network’s topology is also comparable to the blueprints of a new home in which
components such as the electrical system, heating and air conditioning system, and plumb-
ing are integrated into the overall design.
2. In which ways can nodes and links be interconnected?
There are three general interconnection schemes: point-to-point, broadcast, and multi-
drop.
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