Computer Network and commpunitcation 1.pptx

Data communication and computer network presentation slides

1. Computer Network Unit 1 Data Communication and Computer Network

2. Introduction and necessity of computer networking A computer network is a group of devices connected with each other through a transmission medium such as wires, cables etc. A  computer network  is a set of computers sharing resources located on or provided by network nodes. The computers use common communication protocols over digital interconnections to communicate with each other. These interconnections are made up of telecommunication network technologies, based on physically wired, optical, and wireless radio-frequency methods that may be arranged in a variety of network topologies. The purpose of having computer network is to send and receive data stored in other devices over the computer network.

3. Network goals and motivation Resource Sharing- The main goal of the computer network is Resource Sharing. It is to create all the programs, data and hardware accessible to anyone on the network without considering the location of resource and the user. Reliability- If there are alternate sources of supply, all files could be replicated on two or, machines. If one of them is not available, due to hardware failure, the other copies could be used. Inter-process Communication – Network users, located geographically apart, may converse in an interactive session through the network.  Flexible access – Files can be accessed from any computer in the network. The project can be begun on one computer and finished on another . Cost Reduction – Smaller Computers have much better price/performance compared to larger ones. Mainframes are may faster one but costly as well. Communication – A file that was modified or updated on a network can be seen by the other users on a network immediately.

4. Network Protocols A network protocol is an established set of rules that determine how data is transmitted between different devices in the same network. Types of protocols are explained below TCP IP HTTP HTTPS FTP SMTP POP IMAP

5. Network Protocols TCP (Transmission Control Protocol): TCP is used to transfer the data over the internet. It divides the data into small packets and sends it to the destination through the network and make sure that no packets got lost in transmission. The use of packets facilitates speedy transmission since different parts of a message can be sent by different routes and then reassembled at the destination. Tcp used for connection establishment between device and Ip finds the address of system and sends their and tcp disconnect the connection

6. Network Protocols 2.IP (Internet Protocol): Internet Protocol (P) is the method used to route information to the proper address. Every computer on the internet has to have its own unique address known as the IP address. Every packet sent will contain an IP address showing where it is supposed to go. Note IP does not make physical connections between computers but relies on TCP for this function.

7. Network Protocols 3. HTTP (Hyper Text Transfer Protocol): HTTP is an application protocol that is used in the address bar of the web browser before WWW. It defines a mechanism for communication between the browser and the web browser. Whenever we search anything in the address of browser so it brings that website in front of us. It uses port 80.

8. Network Protocols 4. HTTPs (Hypertext Transfer Protocol over Secure Socket Layer) It defines secure communication between a web server and a web browser. A web page using this protocol will have https: at the front of its URL. It uses port 443.

9. Network Protocols 5. File Transfer Protocol The File Transfer Protocol is a standard communication protocol used for the transfer of computer files from a server to a client on a computer network. FTP is built on a client–server model architecture using separate control and data connections between the client and the server. It uses tcp / ip protocol to enable data transfer.

10. Network Protocols 6. Simple Mail Transfer Protocol SMTP is a set of communication guidelines that allow software to transmit an electronic mail over the internet is called Simple Mail Transfer Protocol. It is a program used for sending and receiving messages to other computer users based on e-mail addresses. There are 2 more protocol with SMTP(POP and IMAP).

11. Network Protocols 7. Post Office Protocol POP is a message access protocol that extracts and retrieves email from a remote mail server for access by the host machine. POP is an application layer protocol in the OSI model that provides end users the ability to fetch and receive email. POP send mail from sender to receiver and have no backup

12. Network Protocols 8.IMAP(internet mail access protocol) Internet Message Access Protocol (IMAP) is a better version of POP. By using IMAP the main advantage is user can retrieve our deleted email from the server. 9. User Datagram Protocol   (UDP) is a communications protocol that is primarily used to establish low-latency and loss-tolerating connections between applications on the internet. It is connection less and unreliable protocol. It transfer data without establishing connection. It transfer data in a short distance. Use ip service to send data. UDP speeds up transmissions by enabling the transfer of data before an agreement is provided by the receiving party.

13. Network Protocols 10. TELNET Telnet is an application protocol used on the Internet or local area network to provide a bidirectional interactive text-oriented communication facility using a virtual terminal connection. User data is interspersed in-band with Telnet control information in an 8-bit byte oriented data connection over the Transmission Control Protocol(TCP). 11. DHCP DHCP is a network management protocol used to dynamically assign an IP address to many devices/node on a network so they can communicate using IP(Internet Protocol). DHCP is also used to configure the proper subnet mask, default gateway, and DNS server information on the device. It uses port 68.

14. Networking Model The two most important network models are the Open Systems Interconnection Reference (OSI) and the Internet Model. OSI Model The OSI Model (Open Systems Interconnection Model) is a conceptual framework used to describe the functions of a networking system.

15. Networking Model

16. OSI Layer Application Layer This layer is responsible for providing an interface to the application user. It provides protocols that allow software to send and receive information and present meaningful data to users. A few examples of application layer protocols are the  (HTTP), (FTP), (POP), (SMTP). Presentation Layer The presentation layer prepares data for the application layer. Session layer The session layer creates communication channels, called sessions, between devices.

17. OSI Layer d. Transport Layer The transport layer takes data transferred in the session layer and breaks it into “segments” on the transmitting end. It is responsible for reassembling the segments on the receiving end, turning it back into data that can be used by the session layer. e. Network Layer The network layer has two main functions. One is breaking up segments into network packets, and reassembling the packets on the receiving end. The other is routing packets by discovering the best path across a physical network. The network layer uses network addresses (typically Internet Protocol addresses) to route packets to a destination node.

18. OSI Layer f. Data Link Layer The data link layer establishes and terminates a connection between two physically-connected nodes on a network. It breaks up packets into frames and sends them from source to destination. g. Physical Layer The physical layer is responsible for the physical cable or wireless connection between network nodes. 

19. OSI Layer

20. Networking Model

21. Internet Model Application Layer Transport Layer Internet Layer Link Layer

22. Internet Model The four layers in the TCP/IP protocol suite are − Network Access Layer − It is the lowest layer that is concerned with the physical transmission of data. TCP/IP does not specifically define any protocol here but supports all the standard protocols. Internet Layer − It defines the protocols for logical transmission of data over the network. The main protocol in this layer is Internet Protocol (IP) and it is supported by the protocols ICMP, IGMP, RARP, and ARP. Transport Layer −  It is responsible for error-free end-to-end delivery of data. The protocols defined here are Transmission Control Protocol (TCP) and User Datagram Protocol (UDP). Application Layer −  This is the topmost layer and defines the interface of host programs with the transport layer services. This layer includes all high-level protocols like Telnet, DNS, HTTP, FTP, SMTP, etc.

23. Application and use of networks Communication It is used for sending and receiving a message from one and other through network by using electronic mail. Accessing Resources Networks allow computers to share and access resources with other computing devices connected to it. Centralization of data Data can be stored on one server instead of several devices. For example, on a small home network, all the data can be centralized by using a server. By doing this, anyone with access to the network can work with the data stored on the central server without needing to connect several external hard drives or flash drives to a computer.

24. Application and use of networks 5. Transfer of files One way in which data and information can be shared on a network is by sharing files. By sharing files, you allow users connected to the same network (whether that is a local network or the internet) to gain access to specific files. 6. Increase Productivity The use of networks allow most people to work and study more productively . 7. Entertainment Access to the internet provides access to an almost unlimited amount of entertainment. Examples include: games , multimedia, books, movies.