Chapter 2 1 Topologies Chapter 2
May 16, 2015
Chapter 2 1
Topologies
Chapter 2
Chapter 2 2
Chapter Objectives
Explain the different topologies Explain the structure of various topologies Explain the difference between logical and physical
topology
Chapter 2 3
Recall
Different types of computer networks are LAN, CAN, MAN and WAN
OSI layers are Physical, Data Link, Network, Transport, Session, Presentation and Application layer
The factors of network selection criteria are Performance, Reliability and Security
Standards organization is unit which develops, maintains, improves, amends and revises standards
Chapter 2 4
Introducing Topologies
Topology refers to physical or logical arrangement of network
Physical topologies are Single Node Bus Star Ring Mesh Tree Hybrid
Chapter 2 5
Single Node Topology - I
Single device, at times device called dumb terminal is connected to the server
Devices operates on files from server and returns them back after completing task
Chapter 2 6
Single Node Topology - II Advantages:
Easy to install, configure and manage
Least expensive
Single cable is required
Disadvantages:
Network consists of single device
Dumb terminal is dependent on server
Chapter 2 7
Bus topology - I
All devices are connected to a common cable called backbone/trunk
Operates in daisy chain fashion Medium is shared that’s why creates collision
Chapter 2 8
Bus topology - II
Server is at one end and devices are at different positions
50 ohm terminators are used Devices are not responsible for data transmission
Chapter 2 9
Bus topology - III
Advantages:
Installation of devices is easy
Works better for smaller network
Less expensive
Disadvantages:
If backbone breaks, entire network gets down
Difficult to isolate problems
Limited number of devices can be attached
Chapter 2 10
Star Topology - I Each device is connected to a central device called
hub through cable Data passes through hub before reaching
destination
Chapter 2 11
Star Topology - II
Advantages:
Easy to install, configure, manage and expand
Centralized management
Addition or removal of device does not affect the whole network
Disadvantages:
Requires more cable
Failure of hub affects entire network
More Expensive
Chapter 2 12
Ring Topology - I
Devices are connected in a closed loop
All devices have equal access to media
Device waits for its turn to transmit
Most common type is Token Ring network
Chapter 2 13
Ring Topology - II
Advantages:
Reliable and offers greater speed
No collisions
Handles large volume of traffic
Disadvantages:
More cabling is required compared to bus topology
One faulty device affects the entire network
Addition of devices affect network
Chapter 2 14
Dual Ring Topology
Consists of two independent primary and secondary rings
Secondary ring is redundant, used only when primary stops functioning
Chapter 2 15
Use CBT for quiz and for rest topologies
Chapter 2 16
Mesh Topology - I
Used in WANs to interconnect LANs
Every device is connected to every other device
Use routers to determine the best path of communication
Chapter 2 17
Mesh Topology - II
Types
Full mesh Partial mesh
Full mesh topology – All devices are connected to each other
Partial mesh topology - Some devices are connected to only those with whom they exchange most of the data
Chapter 2 18
Mesh Topology - III
Advantages:
Improves fault tolerance
Failure of one link does not affect entire network
Centralized management is not required
Disadvantages:
Difficult to install and manage
Each link from one device to other requires individual NIC
Expensive
Chapter 2 19
Tree Topology - I
Combines the characteristic of linear bus and star topology
Devices are wired to root hub
Twisted pair cable is commonly used
Lowest level devices are smaller computers
Chapter 2 20
Tree Topology - II
Advantages: Easy to expand the
network Point-to-point wiring for
each device Fault detection is easy
Disadvantages: Difficult to configure If backbone breaks,
entire network goes down
More expensive
Chapter 2 21
Hybrid Topology - I
Combines two or more different physical topologies Commonly Star-Bus or Star-Ring Also known as special topology and useful for
corporate offices
Chapter 2 22
Hybrid Topology - II
Advantages:
Used for creating larger networks
Handles large volume of traffic
Fault detection is easy
Disadvantages:
Installation and configuration is difficult
More expensive than other topologies
More cabling is required
Chapter 2 23
Case Study 1
MoneyMaker Bank at Mumbai has implemented a star topology in their IT department. All computers are connected to the central switch. In the Loan department, all computers are connected in closed loop format. Network administrator, John wants to connect these two networks so that data can be shared among different departments.
Chapter 2 24
Problem
Connect two different departments
Chapter 2 25
Suggested Solution
The administrator can join these two star and ring networks to form a hybrid network with the help of Multistation Access Unit (MAU). It is a centralized hub. Ensure that there is no break in the link between two computers in a ring network and switch in star network is working properly.
Logical Vs Physical Configuration
Physical topology - Defines how the systems are physically connected
Logical topology - Defines how the systems communicate across the physical topologies
Chapter 2 26
Chapter 2 27
Summary - I
Network is an interconnection of many communicating entities that are connected for the purpose of data communication
Topology describes the way in which networking devices are connected to each other
Physical topologies are how the wires are interconnected, while logical topology is how the network behaves and interoperates
Different types of topologies are Single Node, Star, Bus, Ring, Mesh, Tree and Hybrid
Chapter 2 28
Summary - II
In a single node topology, just a single device called dumb terminal is connected to the server
Bus topology connects each device to a single cable and at either end of the cable terminator is used to remove unsent data from the cable
In star topology, multiple devices are connected to a central connection point known as hub or switch
In a ring topology, data travels around the loop in one direction and passes through each device
Chapter 2 29
Summary - III
In a mesh topology, every device is connected to each and every node in the network with many redundant interconnections at least two paths to and from every node
Tree topology connects multiple star networks to other star networks using bus topology
Hybrid topology is a combination of different topologies such as Star-Bus or Star-Ring