A computer network allows computing devices to communicate and share resources. It consists of clients that request resources and servers that provide access to resources. There are several types of networks including LANs, MANs, and WANs. LANs are used in small areas like offices and connect devices using TCP/IP. WANs connect servers and computers across large distances like continents. Network topologies describe how network components are arranged both physically and logically. Common topologies include bus, star, ring, tree and mesh, with each having advantages and disadvantages for things like ease of use, reliability and cost.

1. Introduction of Computer Network:
• A network consists of two or more entities or objects sharing resources and
information.
• A computer network consists of two or morecomputing devices connected
to each other to shareresources and information.
• The network becomes a powerfultool when computers communicate and
shareresources with other computers on the same network or entirely
distinct networks.
• Computers on a network can act as a client or a server.
• A client is a computer that requests for resources.
• A server is a computer that controls and provides access to resources.
• Data is a piece of information.
• The computing concept ‘hierarchy of data’ is used when planning a
network.
• Itis essential to maintain a hierarchy of data to manage and control
resources among computers.
• Network access to data must be evaluated carefully to avoid security issues.
Types of Networks:
LAN (Local Area Networking)
MAN (Metropolitan Area Networks)
WAN (Wide Area Networks)

2. LAN (Local Area Networking):
Local Area Networking is used
primarily in small areas such as
schools, hospitals and office buildings.
Local Area Networking, is one of the
older types of networks. TCP/IP is
used as the method of communication
between computers in Local Area
Networking. Dueto its small size, it is
possiblefor one person to administrate a Local Area Network. LocalArea
Networks areviable to quick change, using a bus network topology that allows for
easy access to the Local Area Network.
connected to the internet by different networking topology.
MAN(MetropolitanArea Networks) :
Metropolitan Area Networks arenot
commonly used these days, they are
used to create communication
between systems in an entire city.
Hence a Metropolitan Area Network
area falls between the sizes Local
Area Networks, and Wide Area
Networks. Metropolitan Area
Networks areused by city specific
businesses such as the New York
Times in the state of New York.

3. WAN (Wide Area Networks):
Wide Area Networks areused to connect
server machines and computers across
continents are countries for constant
information updates. Wide Area Networks,
are used across the globe, many networks
connect with one another across continents
to create one giant Wide Area Network. Wide
Area Networks useoptic fiber as their
communication medium. The largest example
of a Wide Area Network is the internet itself,
which connects all users to the information
and data that is available on the the internet.
What is a Topology?
• Network topologies describe the ways in which the elements of a network are
mapped. They describe the physicaland logical arrangementof the network
nodes.
• The physicaltopology of a network refers to the configuration
of cables, computers, and other peripherals.
DifferentTypes of Topologies
• Bus Topology
• Star Topology
• Ring Topology
• Mesh Topology
• Tree Topology
• Hybrid Topology

4. 1. 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) areconnected to the linear
cable.
• Popular on LANs becausethey are inexpensive and easy to install.
Advantagesof BusTopology
• Itis Cheap, easy to handle and implement.
• Require less cable.
• Itis bestsuited for small networks.
Disadvantagesof Bus Topology
• The cable length is limited. This limits the number of stations that can be
connected.
• This network topology can performwell only for a limited number of nodes.

5. 2. Ring Topology
• In a ring network, every device has exactly two neighboursfor communication
purposes.
• All messages travelthrough 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 weuse 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.
Advantageof Ring Topology
• Very orderly network whereevery 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.

6. Disadvantagesof Ring Topology
• The failure of a single node of the network can causethe entire network to fail.
• The movement or changes made to network nodes affects the performanceof
the entire network.
3. 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 fromany node and passes it along to all the
other nodes in the network.
• Data on a star network passes through thehub, 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.

7. Advantagesof 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 removeparts.
Disadvantagesof Star Topology
• Requires more cable length than a linear topology.
• If the hub or concentrator fails, nodes attached are disabled.
• Moreexpensive because of the cost of the concentrators.

8. 4. 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 fromone 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 controland easier troubleshooting.
• This is particularly helpful for colleges, universities and schools so that each of
the connect to the big network in someway.
Advantagesof a Tree Topology
• Point-to-pointwiring for individual segments.
• Supported by severalhardwareand softwarevendors.
• All the computers haveaccess to the larger and their immediate networks.

9. Disadvantagesof a Tree Topology
• Overalllength of each segment is limited by the type of cabling used.
• If the backboneline breaks, the entire segment goes down.
• Moredifficult to configureand wire than other topologies.
5. MeshTopology
• 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 messageto destination through
multiple paths.
• While the data is travelling on the Mesh Network it is automatically configured
to reach the destination by taking the shortestroutewhich means the least
number of hops.

10. Advantageof Mesh Topology
• No traffic problem as there are dedicated links.
• Ithas 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.
Disadvantageof 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 costis high.

11. 6. Hybrid Topology
• A combination of any two or more network topologies.
• A hybrid topology always accrues when two different basic network topologies
are connected.
• Itis a mixture of abovementioned topologies. Usually, a central computer is
attached with sub-controllers which in turn participate in a variety of topologies.
Advantagesof a Hybrid Topology
• Itis extremely flexible.
• Itis very reliable.
Disadvantagesof a Hybrid Topology
• Expensive