students today we will talk about computer network observe the picture given above what do you see yes you are right that's Railways Network do you know how the Indian Railway system works Indian Railway is the fourth largest railway Network in the world in terms of size India is a geographically vast country with a wide Railway Network system that connects one part of the country to another a large number of Railway stations are interconnected with each other through railway lines trains run on these railway lines that form a network like the railway Network the computers are also interconnected and together they form a computer network in a railway Network the trains can move from one station to another using railway lines that are connected these trains can transport passengers and go from one station to another recently government of India also started with specialized trains known as kissan trains to transfer agriculture products of farmers similarly in a computer network computer can send and receive information using various communication channels like wired and wireless channels computer network in Friendship we often share thoughts emotions and things that we like with with our friends similarly in order to share information two or more computers also need to be connected a computer network consists of two or more computers that are interconnected with each other using different mediums of communication all these computers are connected with each other in such a way that they can share information and at times Hardware resources amongst each other first let us talk about the need for a computer n Network let's now discuss the benefits of a computer network a computer network can prove to be highly beneficial for an organization in several ways given below are some of the benefits of a computer network sharing resources in computer terminology resources constitute of information or data apps and Hardware devices computers that are connected over a network can share these resources for example in a network there can be a single computer with a printer attached to it all other computers that are part of the network can use the Network Services of the same printer reducing data redundancy imagine that there are 100 employees working in an organization and all of them want to work on the same file what according to you would be the best way of sharing the same file with all the employees at one single time one way is to store an individual copy of the same file on all computers this will lead to rency or duplication of data the other way is to connect all the computers over a network and store a single copy of the file on a central computer so that the other connected computers can access the file as in when required this will help in reducing duplication of data see cost we can read how different Hardware resources can be shared by all the computers that are connected over a single Network this does not call for the need to buy multiple products for example a single modem can serve the purpose of providing internet to many devices that are connected over a network like a family of five members can use a single car and need not buy five different cars security security becomes a vital factor in securing the information that is shared by different computers over a network this can be achieved by using various techniques like installing a firewall system and other network protection apps available in different platforms this helps in combating data theft and Fishing Network and its tyes personal area network pan it is a computer network that caters to an individual user it is used for establishing communication among devices such as laptops mobile phones or smartphones this type of network is suitable for home users pan generally covers a range of up to around 10 m Wireless channels can be used for establishing a connection between different devices we can use these networks to transfer different types of files local area network lamb the local area network is confined to a limited area such as a room an office building or a school or a college campus as the area covered by Lan is limited the data transmission speed in Lan is very fast and can be easily maintained in land the computer terminals are physically connected with wires when computer systems connect without wires in a local area network it is called W LAN metropolitan area network man the metropolitan area network is spread across a city as compared to Lan it covers a wider area the computers in a man network can be connected through wires as well as through wireless communication mediums ATM machines of a specific bank installed at different locations in a city are example of man these ATM machines can share data with with other ATM machines and can also share data with the Central Computer that is installed in the main branch of the bank wide area network van the world that we see consists of large continents even the terrain of all these continents are different from each other thus it is a challenging situation wherein the engineers try to develop networks that will provide uninterrupted network connectivity one Prov provides satellite based communication and the signals can penetrate remote areas thereby providing continuous network connectivity one provides internet connectivity through Satellite Communication channels topologies Network topology refers to the arrangement of various components of a network in a way that facilites easy communication before you start with the arrangement of network components it is important to Define how the information will flow between these components this is called logical topology second is how these components will be physically arranged the arrangement of network components is called physical topology Network topologies are categorized into the following basic types point to point out of all the available Network topologies this topology is very popular as it is simple to use it is used to establish direct communication between two Network components example computers routers Hub Etc a direct link can be established using wired and wireless Technologies Bas topology in a human body the spine or what we call the backbone supports the body's entire structure similarly in a network in which all the computers are connected with the main cable these connected computers transmit data in a single Direction such networks form bus topology the bus topology is widely used in places where the floor area is small it is suitable for home office and shops just like other network topologies this topology also has a disadvantage the breakdown of main Cable in bus topology will led to the failure of the entire network St topology in St topology the central server acts as a master computer or a server devices communicate across the network by passing data through this master computer install topology each device is connected to a server computer using a Point to-point connection popular in use in this topology it is easy to add a new device to the network work with the help of only one cable the configuration to is simple it is more robust than the bus topology because if a connection in the network fails the other connections remain intact the entire network goes down only if the central computer or Hub fails ring topology in a ring topology the computers are connected in a ring like structure the formation of the connected computers looks is like a circle with dots placed on it together all the connected devices in this phone are called a ring Network in ring network data travels from one computer to another until it reaches its destination computer in a ring topology we do not need a central computer or a server to handle data each computer in itself works as a server computer and helps in the transmission of data a major disadvantage of this type of network is it is difficult to add or repair a single computer while the data is passing through the network in this type of network If one computer stops working the entire network goes down tree topology the tree topology is a particular type of structure where many connected Network components are arranged like a tree's branches a tree topology is a compin combination of a star Network topology and a bus topology since any two nodes can have only two mutual connection tree topology creates a natural parent and child hierarchy in a tree topology there can only be one connection between any two connected computers the tree topology is frequently used to organize the computers in a large corporate Network or for database related Services there are few disadv vantages of tree topology as compared to bus and star topology large cabling is required tree network is very difficult to manage and configure in tree topology all the computers are connected with a hum if the Hub fails to work properly the entire network fails mesh topology in the mesh Network topology computers are connected in an arbitrary fashion in this type of topology each comp computer can send its signal to the other computers in the network along with that it also helps in retransmitting the data to other computers on the network this topology setup allows major Transmissions to be distributed even if one of the connections goes down it is a topology commonly used for wireless networks the overall cost of maintaining this type of network is too high peer-to-peer Network a peer-to-peer network is the one where where a few computers of equal capacity and capabilities are connected together to use the resources available on the web in a peer-to-peer Network there is no Central server instead each computer can act both as a server and a client client server architecture in a client server Network several computers called clients or workstations are connected to the main computer called the server a server is a computer that provides services to clients and controls access to Hardware software and other resources clients are the computers that request services like data retrieval storage Etc from the server let us quickly have a look on chapter review computers that are connected over the network can share resources computer networks help in reducing redundency the local area network is confined to a limited area such as a small room home the metropolitan area network is spread across the city wide area network connects two or more computers located in distant places Network topology refers to the arrangement of various components of a network in a way that facilitates easy Communication in bus topology the main cable acts as a backbone for the network in St topology the central server acts as a master computer or a server ring topologies are used in both Lan and Van setups a tree topology is a particular type of structure where many connected Network components are arranged like a tree branches in a client server Network several computers called clients or workstations are connected to the main computer called the server