ALL ABOUT OSI MODEL

OSI MODEL

(OPEN SYSTEM INTERCONNECTION)

It is the most important topic of networking that is frequently asked in all competitive exams so I try to explain it in brief and easy manner.

OSI stands for Open system Interconnection model which is used for communication of applications over the network. It is the product of Open Systems Interconnection Project at the International Organization for the Standardization. This model defines a networking framework to implement protocols in seven layers. It is also called a seven layers model because the overall working of this model is divided into seven layers. Each layer receives the services from its lower layer and provide service to its upper layers.

The below four layers (i.e, Physical Layer, Data link Layer, Network Layer & Transport Layer) are called the host layers and above three layers of this model (i.e, Session Layer, Presentation Layer & Application Layer) are called the media layers.

PROTOCOLS and TECHNOLOGIES used in each LAYER

Application Layers : Http,https,Telnet,Rdp,Smtp,pop3,Smb,Ftp

Presentation Layer: encryption, ASCII, EBCDIC, TIFF, GIF, PICT, JPEG, MPEG, MIDI

Session Layer : NFS, NetBios names, RPC, SQL, Sockets

Transport Layers :TCP,UDP

Network Layers :IP,ARP,ICMP,RARP

Datalink Layers : PPP, FDDI, ATM, IEEE 802.5/ 802.2, IEEE 802.3/802.2, HDLC,

FrameRelay, Ethernet, FDDI, Token Ring, 802.11 Standards 

Physical Layer: Ethernet, FDDI, B8ZS, V.35, V.24, RJ45.

TYPE OF DATA HANDLE

Physical layer –bits

Data link layer-frames

Network layer-datagrams or packet

Transport Layer-Segment

Presentation Layer-Encoded data

Application layer-User data.

RESPONSIBILITIES OF EACH LAYER in OSI Model

Physical layer- Encoding and Signaling,Transmission modes, Hardware Specifications, Topology

Data Link Layer-Data Framing, Addressing,Error Detection and Handling,Flow Control

Network Layer-Logical Addressing ,Routing

Transport Layer- Segmentation and Reassembly, Acknowledgments and Retransmissions, Flow Control, Error Control, Service Point addressing

Session Layer-Dialog Control(half/full duplex), Synchronization

Presentation Layer- Compression and Encryption, Translation

Application Layer-User applications

Devices used by Each Layer

Repeater-Physical Layer
Bridge-Data Link Layer
HUB-Multiport Repeater-Physical Layer-
Switch-Multiport Bridge-datalink-used for LAN connection
Router-Multiple LAN connection-Network-used for LAN-LAN Comm,WAN Comm
Gateway-all layers

Good Day :)