1. Topology Level: Prep-I Topic: Computer Networks Ms. Fouzia Yousuf October 25, 2010

2. What is Topology? A topology is configuration of communication networks and is of two types, Physical and Logical. Physical topology refers to configuration of computers, cables, devices and mostly depends on various factors. A logical topology is a method of transmitting or passing data between workstations.

3. Types of Physical Topologies Bus Network (also known as Liner Bus) Star Topology (Centralization) Ring Topology (also known as Star-Wired or Token Ring Network) Tree Mesh Topology

4. BUS Topology A bus network is a network architecture in which a set of clients are connected via a shared communications line, called a bus. There are several common instances of the bus architecture, including one in the motherboard of most computers, and those in some versions of Ethernet networks.

5. Star Topology In a Star Topology each computer is directly connected to the centralized Hub or a Switch. In this way, when computer A sends a data packet for computer B, the data flows through the Hub or Switch to which both computer A and B are connected. Different types of cables can be used in this scenario like coaxial cable, fibre optic cable and twisted pair cable.

6. Token Ring / Star-Wired A token ring topology is architecturally similar to star topology. The only difference here is that it is created of wiring that would allow transfer of data from one computer to another in a ring (or circle). A token ring network will pass information based on token system.

7. Tree Topology A tree topology combines characteristics of linear bus and star topologies. It consists of groups of star- configured workstations connected to a linear bus backbone cable. Tree topologies allow for the expansion of an existing network with ease.

8. Mesh Topology A fully connected or complete topology is a network topology in which there is a direct link between all pairs of nodes. In a fully connected network with n nodes, there are n(n-1)/2 direct links. Synonym fully connected mesh network.

9. Summary See the below table for a quick understanding and comparison of topologies, cable media and protocols used. TopologyCable MediaProtocol Used Linear BusTwisted Pair Coaxial, Fiber Ethernet, Local Talk StarTwisted Pair Fiber Ethernet, Local Talk Token / Star – wired Ring Twisted PairToken Ring TreeTwisted Pair Coaxial, Fiber Ethernet