Computer Network Topologies
Dr R. Singh
CS & IT, MJPRU, Bareilly
rsiet2002@gmail.com
Dean, FET, hod.ch@mjpru.ac.in
Registrar, registrarmjpru@gmail.com
Basic Terminology
Network: Collection of loosely coupled processors
interconnected by communication links using
cables, wireless technology, or both
Goal: To provide a convenient way to share
resources (hardware and software) while
controlling users’ access to them
General configurations for OS for networks:
Network operating system (NOS)
Distributed operating system (D/OS)
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Basic Terminology
(continued)
Network operating system (NOS):
Networking capability added to single-user
operating system
Users aware of specific computers and
resources in the network
Access via logon to remote host or by
data transfer from remote host
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Basic Terminology (continued)
Distributed operating system (D/OS): Users can
access remote resources as if local resources
Good control for distributed computing systems
Allows resources to be accessed in a unified way
Represents total view across multiple computer
systems for controlling and managing resources
without local dependencies
Management is a cooperative process
Comprised of managers with a wider scope
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Basic Terminology (continued)
D/OS must provide the following
components:
Process or object management
Memory management
File management
Device management
Network management
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Basic Terminology (continued)
Figure 9.1: Networked management system
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Basic Terminology (continued)
Advantages of D/OS over traditional systems:
Easy and reliable resource sharing
Faster computation
Adequate load balancing
Good reliability
Dependable electronic communications
among the network’s users
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Basic Terminology (continued)
In distributed system each processor classifies other
processors and resources as remote and considers its own
resources local
Site: Indicates a specific location in a network with one or
more computers
Host: Specific computer system found at a site whose
services and resources can be used from remote locations
Node: Refers to the name assigned to a computer system
connected to network to identify it to other computers in
network
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Basic Terminology (continued)
Clients request data or services from the host server and wait for the
response. If the client host has resources needed by the server host,
the roles can be reversed
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Types of connections: point-to-point and multipoint
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What is a Topology?
Network topologies describe the ways in which the
elements of a network are mapped. They describe
the physical and logical arrangement of the
network nodes.
The physical topology of a network refers to the
configuration of cables, computers, and other
peripherals
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Network Topologies
Sites in any networked system can be physically or
logically connected in a variety of topologies
In each topology there are trade-offs between
Need for fast communication among all sites
Tolerance of failure at a site or communication
link
Cost of long communication lines
Difficultyof connecting one site to a large
number of other sites
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Network Topologies
(continued)
Four basic criteria :
Basic cost: Expense required to link the various sites in
the system
Communications cost: Time required to send a
message from one site to another
Reliability: Assurance that many sites can still
communicate with each other if a link or site fails
User’s environment: Critical parameters that network
must meet to be a successful business investment
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Categories of topology
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Other Topologies
Tree Topology
Hybrid Topology
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Bus Topology
All the nodes (file server, workstations, and
peripherals) on a bus topology are connected
by one single cable.
A bus topology consists of a main run of cable
with a terminator at each end. All nodes (file
server, workstations, and peripherals) are
connected to the linear cable.
Popular on LANs because they are inexpensive
and easy to install.
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Bus Topology
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Bus Topology
Advantages of Bus Topology
It is Cheap, easy to handle and implement.
Require less cable
It is best suited for small networks.
Disadvantages of Bus Topology
The cable length is limited. This limits the number of
stations that can be connected.
This network topology can perform well only for a
limited number of nodes.
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Ring Topology
In a ring network, every device has exactly two
neighbours for communication purposes.
All messages travel through a ring in the same
direction.
A failure in any cable or device breaks the loop and can
take down the entire network.
To implement a ring network we use the Token Ring
technology
A token, or small data packet, is continuously passed
around the network. When a device needs to transmit,
it reserves the token for the next trip around, then
attaches its data packet to it.
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Ring Topology
Ring Topology
Advantage of Ring Topology
Very orderly network where every device has access to
the token and the opportunity to transmit.
Easier to Mange than a Bus Network
Good Communication over long distances
Handles high volume of traffic
Disadvantages of Ring Topology
The failure of a single node of the network can cause
the entire network to fail.
The movement or changes made to network nodes
affects the performance of the entire network.
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Star Topology
In a star network, each node (file server, workstations,
and peripherals) is connected to a central device called
a hub.
The hub takes a signal that comes from any node and
passes it along to all the other nodes in the network.
Data on a star network passes through the hub, switch,
or concentrator before continuing to its destination.
The hub, switch, or concentrator manages and controls
all functions of the network.
The star topology reduces the chance of network failure
by connecting all of the systems to a central node.
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Star Topology
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Star Topology
Advantages of Star Topology
Easy to manage
Easy to locate problems (cable/workstations)
Easier to expand than a bus or ring topology.
Easy to install and wire.
Easy to detect faults and to remove parts.
Disadvantages of Star Topology
Requires more cable length than a linear topology.
If the hub or concentrator fails, nodes attached are disabled.
More expensive because of the cost of the concentrators.
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Tree Topology
A tree topology (hierarchical topology) can be viewed as
a collection of star networks arranged in a hierarchy.
This tree has individual peripheral nodes which are
required to transmit to and receive from one other only
and are not required to act as repeaters or
regenerators.
The tree topology arranges links and nodes into distinct
hierarchies in order to allow greater control and easier
troubleshooting.
This is particularly helpful for colleges, universities and
schools so that each of the connect to the big network
in some way.
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Tree Topology
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Tree Topology
Advantages of a Tree Topology
Point-to-point wiring for individual segments.
Supported by several hardware and software vendors.
All the computers have access to the larger and their
immediate networks.
Disadvantages of a Tree Topology
Overall length of each segment is limited by the type of
cabling used.
If the backbone line breaks, the entire segment goes down.
More difficult to configure and wire than other topologies.
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Mesh Topology
In this topology, each node is connected to every other
node in the network.
Implementing the mesh topology is expensive and
difficult.
In this type of network, each node may send message to
destination through multiple paths.
While the data is travelling on the Mesh Network it is
automatically configured to reach the destination by
taking the shortest route which means the least number
of hops.
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Mesh Topology
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Mesh Topology
Advantage of Mesh Topology
No traffic problem as there are dedicated links.
It has multiple links, so if one route is blocked then other
routes can be used for data communication.
Points to point links make fault identification easy.
Disadvantage of Mesh Topology
There is mesh of wiring which can be difficult to manage.
Installation is complex as each node is connected to every
node.
Cabling cost is high.
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Hybrid Topology
A combination of any two or more network
topologies.
A hybrid topology always accrues when two
different basic network topologies are
connected.
It is a mixture of above mentioned topologies.
Usually, a central computer is attached with
sub-controllers which in turn participate in a
variety of topologies
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A hybrid topology: a star backbone with three bus networks
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Hybrid Topology
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Hybrid Topology
Advantages of a Hybrid Topology
It is extremely flexible.
It is very reliable.
Disadvantages of a Hybrid Topology
Expensive
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References
1. Computer Networks (Books and Slides)— Andrew S Tanenbaum, 4th Edition. Pearson,
Education/PHI Publication
2. Data Communications and Networking (Books and Slides) – Behrouz A. Forouzan. Third,
Edition TMH Publication
3. An Engineering Approach to Computer Networks (Books and Slides)-S. Keshav, 2nd
Edition, Pearson Education Publication
4. Understanding communications and Networks, 3rd Edition, (Books and Slides) W.A. Shay,
Thomson Publication
5. Data Networks, (Books and Slides) D. Bertsekas and R Gallager, PHI Publication.
6. Computer Networking: A Top-Down Approach, 6th Edition, James Kurose, Keith W. Ross,
Pearson Education Publication
7. W. Stallings, Data and Computer Communication, Pearson education (Books and Slides).
• http://www.ietf.org
• http://www.tcpipguide.comhttp://en.wikipedia.org
• www.eazynotes.com
• Power point slides by J.F. Kurose, K.W. Ross,
https://gaia.cs.umass.edu/kurose_ross/ppt.htm
• http://www.engppt.com/2009/12/networking-fourozan-ppt-slides.html
Thanks a Lot
Have a nice Day
