chapter 2 topologies

8/8/2019 Chapter 2 Topologies

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Chapter 2 1

Topologies

Chapter 2


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Chapter 2 2

Chapter Objectives

Explain the different topologies

Explain the structure of various topologies Compare different topologies


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Chapter 2 3

Recall

LAN types are Ethernet, Token Ring, Token bus and

Fiber Distributed Data Interface (FDDI).

OSI layers are Physical, Data Link, Network,

Transport, Session, Presentation and Applicationlayer

The factors of network selection criteria are

Performance, Reliability and Security

Standards organization is unit which develops,maintains, improves, amends and revises standards


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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


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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


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Chapter 2 6

Single Node Topology - II

Advantages:

Easy to install,configure and manage

Least expensive

Single cable is required

Disadvantages:

Network consists ofsingle device

Dumb terminal isdependent on server


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Chapter 2 7

Bus topology - I

All devices are connected to a common cable calledtrunk

Maximum segment length of cable is 200 m

Maximum of 30 devices per segment


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Chapter 2 8

Bus topology - II

Server is at one end and devices are at different

positions

50 ohm terminator is used

Devices are not responsible for data transmission Number of collisions are more

Daisy chain method can be used to add more

devices


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Chapter 2 9

Bus topology - III

Advantages:

Installation of devicesis easy

Requires less cablecompared to startopology

Less expensive andworks better for smallernetworks

Disadvantages:

If backbone breaks,entire network gets

down

Difficult to isolateproblems

Limited number ofdevices


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Chapter 2 10

Star Topology - I

Each device is connected to a central device calledhub through cable

Data passes through hub before reachingdestination


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Chapter 2 11

Star Topology - II

Advantages:

Easy to install,configure, manage and

expand

Centralizedmanagement

Addition or removal ofdevice does not affectthe whole network

Disadvantages:

Requires more cable

Failure of hub affectsentire network

More Expensive


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Chapter 2 12

Case Study 1

Hyderabad branch of the MoneyMaker bank has builtan insurance department in such a way that eachdevice is connected to one another. This department

consists of seven agents. It is required that agentsshould handle only their specific clients since theinformation is confidential. But in the existing topologythe data is not secured. So, Smith, the networkadministrator, wants to switch over to other topology.


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Chapter 2 13

Problem

Design a new type of network for this department.


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Chapter 2 14

Suggested Solution

The current topology implemented by the bank is

mesh in which information is shared between differentdevices. To obtain security of data star network seems

to be the best choice. It also provides ease of

troubleshooting, centralized management and ease of

reconfiguration.


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Chapter 2 15

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


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Chapter 2 16

Ring Topology - II

Advantages:

Data travels at greater

speed

No collisions

Handles large volumeof traffic

Disadvantages:

More cabling is

required compared tobus

One faulty deviceaffects the entire

network

Addition of devicesaffect network


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Chapter 2 17

Dual Ring Topology

Consists of two

independent primary

and secondary rings

Secondary ring is

redundant, used only

when primary stops

functioning


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Chapter 2 18

Mesh Topology - I

Used in WANs to

interconnect LANs

Every device is

connected to everyother device

Use routers to

determine the best path

of communication


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Chapter 2 19

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


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Chapter 2 20

Mesh Topology - III

Advantages:

Improves fault

tolerance

Failure of one linkdoes not affect entirenetwork

Centralizedmanagement is notrequired

Disadvantages:

Difficult to install and

manage

Each link from one

device to other

requires individual NIC

Very much expensive


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Chapter 2 21

Tree Topology - I

Connects groups of star

networks

Devices are wired to

root hub Root hub is connected

to second level devices

Lowest level devices

are smaller computers


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Chapter 2 22

Tree Topology - II

Advantages:

Easy to add new

devices

Point-to-point wiring foreach device

Fault detection is easy

Disadvantages:

Difficult to configure

If backbone breaks,

entire network goesdown

More expensive


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Chapter 2 23

Hybrid Topology - I

Combines two or more different physical topologies

Commonly Star-Bus or Star-Ring

Star-Ring uses Multistation Access Unit (MAU)


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Chapter 2 24

Hybrid Topology - II

Advantages:

Used for creating

larger networks

Handles large volumeof traffic

Fault detection is easy

Disadvantages:

Installation andconfiguration is difficult

More expensive thanother topologies

More cabling isrequired


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Chapter 2 25

Case Study 2

MoneyMaker Bank at Mumbai has implemented a

star topology in their IT department.All computers

are connected to the central switch. In the Loandepartment, 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.


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Chapter 2 26

Problem

Connect two different departments


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Chapter 2 27

Suggested Solution

The administrator can join these two star and ring

networks to form a hybrid network with the help of

MultistationAccess Unit (MAU). It is a centralizedhub. Ensure that there is no break in the link

between two computers in a ring network and switch

in star network is working properly.


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Chapter 2 28

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 networkingdevices 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


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Chapter 2 29

Summary - II

In a single node topology, just a single device calleddumb 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 toremove unsent data from the cable

In star topology, multiple devices are connected to acentral connection point known as hub or switch

In a ring topology, data travels around the loop inone direction and passes through each device


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chapter 2 topologies

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