TOPOLOGY
Recall
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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 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
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Introducing Topologies
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Topology refers to physical or logical arrangement of
network
Physical topologies are
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Chapter 2
Single Node
Bus
Star
Ring
Mesh
Tree
Hybrid
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Single Node Topology - I
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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
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Single Node Topology - II
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Advantages:
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Disadvantages:
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Easy to install,
configure and manage
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Network consists of
single device
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Least expensive
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Dumb terminal is
dependent on server
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Single cable is required
Chapter 2
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Bus topology - I
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All devices are connected to a common cable called
trunk
Maximum segment length of cable is 200 m
Maximum of 30 devices per segment
Chapter 2
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Bus topology - II
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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
Chapter 2
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Bus topology - III
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Advantages:
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Installation of devices
is easy
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Requires less cable
compared to star
topology
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Chapter 2
Less expensive and
works better for smaller
networks
Disadvantages:
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If backbone breaks,
entire network gets
down
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Difficult to isolate
problems
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Limited number of
devices
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Star Topology - I
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Each device is connected to a central device called
hub through cable
Data passes through hub before reaching
destination
Chapter 2
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Star Topology - II
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Advantages:
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Easy to install,
configure, manage and
expand
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Centralized
management
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Addition or removal of
device does not affect
the whole network
Chapter 2
Disadvantages:
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Requires more cable
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Failure of hub affects
entire network
More Expensive
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Ring Topology - I
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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
Chapter 2
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Ring Topology - II
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Advantages:
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Data travels at greater
speed
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No collisions
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Handles large volume
of traffic
Chapter 2
Disadvantages:
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More cabling is
required compared to
bus
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One faulty device
affects the entire
network
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Addition of devices
affect network
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Dual Ring Topology
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Consists of two
independent primary
and secondary rings
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Secondary ring is
redundant, used only
when primary stops
functioning
Chapter 2
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Mesh Topology - I
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Chapter 2
Used in WANs to
interconnect LANs
Every device is
connected to every
other device
Use routers to
determine the best path
of communication
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Mesh Topology - II
Types
Full mesh
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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
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Mesh Topology - III
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Advantages:
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Improves fault
tolerance
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Failure of one link
does not affect entire
network
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Chapter 2
Centralized
management is not
required
Disadvantages:
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Difficult to install and
manage
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Each link from one
device to other
requires individual NIC
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Very much expensive
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Tree Topology - I
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Chapter 2
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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Tree Topology - II
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Advantages:
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Chapter 2
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Easy to add new
devices
Point-to-point wiring for
each device
Fault detection is easy
Disadvantages:
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Difficult to configure
If backbone breaks,
entire network goes
down
More expensive
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Hybrid Topology - I
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Combines two or more different physical topologies
Commonly Star-Bus or Star-Ring
Star-Ring uses Multistation Access Unit (MAU)
Chapter 2
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Hybrid Topology - II
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Advantages:
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Disadvantages:
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Used for creating
larger networks
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Installation and
configuration is difficult
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Handles large volume
of traffic
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More expensive than
other topologies
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Fault detection is easy
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More cabling is
required
Chapter 2
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Summary - I
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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
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Summary - II
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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
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Summary - III
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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
Chapter 2
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