OSI MODEL LAYERS |

                                                            OSI MODEL

• PHYSICAL LAYER :- This layer is primary layer of the osi model and consists of connection  devices such as Ethernet cable, Token ring, Hubs, Repeaters and electrical specification for data connection. 

• DATA LINK LAYER :- Data link layer encodes and decodes data packet into bits and using its transmission protocol it handles the errors in the physical layer. this is work on Switch.  MAC address, NIC, Bridge, Framing, Encapsulation, or Error detection.

• NETWORK LAYER :- The Network layer adds the concepts of routing above the Data link layer. Tagging IP Address, Choose best path, Routing. Most used protocol in this layer is internet protocol(IP), Internet packet exchange(IPx), ARP, RARP etc.

• TRANSPORT LAYER :- In the fourth layer variable length data sequence has to be transferred from source to destination host through one or more network. This transport layer delivers data across network connection. The supported prrotocols at this layer are TCP(Transmission control protocol) UDP(User datagram protocol) and SPX(Sequential packet exchange).

• SESSION LAYER  :- Create and manage the session via port number is know as session layer.  Synchronization, Dialog, Control, Reconnection.

• PRESENTATION LAYER :- The presentation layer is the simplest in function of any piece of the OSI model. It handles syntax processing of message data such as format conversions and encryption/decryption needed to support the application layer above it. File Formats are Mp4, AVI, MKV, PNG, JPG etc.

• APPLICATION LAYER :- This is last layer of OSI model and this layer represents the data that is understood by the end user. The application layer supplies network services to end user application. Protocols are FTP, HTTP, HTTPS, TELNET, DNS, SMTP, POP  etc..

OSI MODEL

OSI stand for open systems interconnection or OSI model was first proposed by international standard organization (ISO) to solve the multiple problems faced in telecommunication. It is conceptual model of telecommunication networking where the whole process is divided into seven effective layers. The 7 OSI model layers are:-

1- Physical layer
2- Data link layer
3- Network layer 
4- Transport layer
5- Session layer
6- Presentation layer
7- Application layer

WHAT IS NETWORK?

A network consists of two or more computers that are linked in order to share resources (such as printers and Cd's), exchange files, or allow electronic communications. The computers on a network may be linked through cables, telephone lines, radio waves, satellites, or infrared light beams.






Types of Networks-


1. LAN- LAN stands for local area network. It is used to network computers within a limited area like office, school by using the network media.







2. CAN- Can stand for campus area network. Can is an interconnection of local area networks within a limited geographical area. Can is smaller than a wide area network.



3. MAN- Man stand for metropolitan area network, which optimized for larger geographic area than a LAN ranging from several blocks of buildings to entire city.






4. WAN- Wan stand for wide area network that is a network connection of wide area such as the world.






5. PAN- Pan stand for personal area network which is referred to the interconnection of information technology devices mostly up to 10 meters. these interconnected devices might include laptop computer, mobile phones, printers or other devices.