The document discusses different network topologies including physical, logical, bus, star, ring, mesh, tree, and hybrid topologies. It provides details on the characteristics of each topology such as how computers connect, advantages, disadvantages, and examples. Bus topology involves computers connecting to a shared central cable. Star topology uses a central switching device. Ring topology forms a circular connection between computers. Mesh topology connects each device point-to-point. Tree topology combines star and bus topologies hierarchically. Hybrid topology mixes characteristics of other topologies.

1. NAME : G. BHARATH
REG : 1801711092017

2.  Network topology is how computers connect or relate to one another in a
computer network.
 The data that is transferred from one computer to the other will be in the form of
frames.
→ The data in the network layer will be in the form of IP packets and these IP packets
are packed into frames in data link layer.
→ Physical layers then transmits these frames into the transmission media.

3.  THERE ARE TWO CATEGORIES OF NETWORK TOPOLOGIES:
1. PHYSICAL TOPOLOGY :
• The Physical network topology refers to the physical connections
and interconnections between nodes ( usually the physical
network devices like switches) and the network—the wires,
cables etc.
2. LOGICAL TOPOLOGY :
• The logical network topology is a higher-level idea of
how the network is set up, including which nodes connect
to each other and in which ways, as well as how data is
transmitted through the network. Logical network topology
includes any virtual and cloud resources.

4.  The most common computer network used to interconnect physically
distributed computers is LOCAL AREA NETWORK that includes;
→Bus topology
→Star topology
→Ring topology
→Mesh topology
→Tree topology
→Hybrid topology
 The main difference between these topologies is the arrangement of the
computers.

5. 1. BUS TOPOLOGY :
• In a bus topology computers connect to a shared central cables ( all connected computers
use the same cable for data frame transmission.
• This shared central cable has taps ( connectors ) and drop line ( cables running in between
the bus and the computers ).
• In this topology if a computer sends data frame to a second computer all the other
computers connected to the same central cable will also receive the frame, however only the
target computer accepts it or responds to it and the other computers reject the frame by
checking the destination MAC address in the received frame.

6.  ADVANTAGES :
 very easy to install as there is less cabling works.
 Less expensive to implement when compared to other topologies.
 DISADVANTAGES :
 Since all the data is transmitted over the main cable, there is a limit of drop lines
and the distance a main cable can have.
 With the increase in the length of central cable and increase the count of taps,
the strength signal decreases. Therefore only a limited number of computers can
be connected in this topology.
 In this topology all the computers depend on central cable for data frame
transmission therefore if the central cable fails it paralyses the whole network.
 Security risks as all the computers connected to the central cable receives the
data frame sent from one computer.
 Only one computer can transmit data at a time. If not it may result in data
collision.
• Example of bus topology – Ethernet LAN.

7. 2. STAR TOPOLOGY :
• In star topology computers connect to a central device, which could be a Switch or a Hub.
• The computers in star topology connect with point to point communication links. That
means that there is a dedicated link or cable between the two devices which the other
computers in the network cannot use.
• In this topology if one computer sends some data frame to another computer it will be
routed to the central device and this central device can either broadcast (the transmission
of data to all the connected devices) or unicast (transmission of data to the target device
alone) the received data frame towards the destination computers based on the type of
central device used.
• If the central device is a hub, the data frame sent from one computer is broadcasted to all
the computers in the network but only the target computer accepts it.
• If the central device is a switch, then the data frame sent from one computer is unicasted to
the target computer alone.

8. • To overcome the hub traffic, a switch if preferred to be used as central device. As
every device has its own destination MAC address the switch stores MAC address in a
table format called switch table and sends the data according to the target computer
with the help of this MAC address and also allows simultaneous communications
between the computers in the network without any collision.
 ADVANTAGES :
 in star topology only one input/output port or one cable is used to connect several
devices which makes it less expensive.
 Easy to reconfigure; as we can simply add or remove devices by connecting or
disconnecting cables.
 Good fault tolerance and also easy to detect faults.
 DISADVANTAGES :
 Whole network collapses if the central device fails.
 The number of computers that can be added to the network is limited by the number of
input/output ports in the central device.
• Example of star topology – High speed LANs.

9. 3. RING TOPOLOGY :
• In ring topology each computer connects to two adjacent computers forming a ring.
• The data transmitted from one computer moves to another computer circular in a circular
fashion to reach its final destination.
• The transmission is unidirectional, but it can be made bidirectional by having 2 connections
between each Network Node, it is called Dual Ring Topology.
• In Dual Ring Topology, two ring networks are formed, and data flow is in opposite direction in
them. Also, if one ring fails, the second ring can act as a backup, to keep the network up.
• Data is transferred in a sequential manner that is bit by bit. Data transmitted, has to pass
through each node of the network, till the destination node.

10.  ADVANTAGES:
 Easy installation.
 Less cabling.
 As the data moves in one direction it reduces the chance of data packet collision.
 Detection of computer that stopped receiving data from the neighbouring computer is easier
therefore it is easy to troubleshoot.
 DISADVANTAGES:
 As the data frame has to pass through all the computers between the source and destination
it makes the data transmission slower.
 As all computers connect to form a closed loop, one fault would paralyze the whole network.
 It is difficult to reconfigure because we have to break the ring to add or remove the
computers.
• Example of ring topology – Token ring

11. 4. MESH TOPOLOGY :
• In a mesh topology, each device has point to point link with every device in a network.
→ If the number of devices in a network is n = 4, then the number of links or cables that each
device has is 3 [ n – 1 ].
→ If there are 4 devices in the network, then the total number of links or cables in the network
is 12 [ n(n – 1) ]. And these links are known as SIMPLEX LINKS. In simplex links data moves
in one direction only.
→ whereas in DUPLEX LINKS the data can move in two directions, Therefore two simplex links
can be replaced by one duplex link. And the total number of links or cables in the network
becomes 6 [ n(n-1)/2 ].

12.  ADVANTAGES:
 The presence of dedicated point to point link eliminates traffic problems.
 The dedicated point to point link maintains privacy and security of the data frame
that is shared between two devices.
 Even if one link fails it does not affect the whole network.
 Good fault tolerance.
 DISADVANTAGES:
 Since each devices in the network are interconnected with all the devices it
makes it difficult for installation
 Multiple input/output ports and a large number of cables increase the course and
makes it expensive.
 Since there is need of more cables, it occupies more space.
• Example of Mesh topology – the connection between regional telephone offices.

13. 5. TREE TOPOLOGY:
• A tree topology has combined features that of Bus and Star topology.
Typically to form a tree network, multiple star topologies are combined
together through central cable or a bus.
• A tree topology has a root node and all the other nodes are connected
to it forming a hierarchy and hence it is also called an Hierarchical
topology.
• In tree topology network, one central hub and multiple secondary hubs
are used. The central hub is an active hub.

14.  ADVANTAGES:
 It is an extension of star and bus topologies, so in networks where these
topologies cannot be implemented individually for reasons related to scalability,
tree topology is the best alternative.
 Expansion of network is possible and is easy.
 As the network is divided into segments, it makes it easy for managing and
maintaining the network.
 Error detection is easy.
 Even if one segment is damaged, other segments are not affected.
 DISADVANTAGES:
 Because of its basic structure, tree topology relies heavily on the main bus cable,
if the main bus cable breaks the network is completely crippled.
 As more and more nodes and segments are added, the maintenance becomes
difficult.
• Example of Tree topology – cable TV network.

15. 6. HYBRID TOPOLOGY:
• When all the topologies that were discussed above is
interconnected, this forms the hybrid topology.
• An hybrid topology combines characteristics
Bus topology, Star topology and/or Ring topology.
So an hybrid topology is basically the mixture of two or
more topologies.
ADVANTAGES:
 Reliable because unlike other networks fault detection and troubleshooting is easy in this type
of topology.
 It is easy to increase the size of the network by adding new components, without disturbing the
existing architecture.
 This topology is flexible and effective.
DISADVANTAGES:
 Major disadvantage is the complexity of the network in this topology.
 Very expensive when compared to other network topologies.