OSI Layer

Compare and contrast OSI and TCP/IP models :

1.Physical Layer: 

    it is responsible for moving data form one node to the next. 

Function:

I. Transmission media
II. Types of encoding
III. Data rate{no of bits sent each sec}
IV. Synchronization of bits.
V. Line configuration (Example: point to point , multipoint)
VI. Topology (Bus,Star,Ring,Mesh)
VII. Transmission (simplex ,half duplex, full duplex)

2.Data like Layer: 

    it transforms the physical layer into a reliable link.

Function:

I.Framing: conversion of bits to frames. framing are working in four methods can be used to mark the start to end of frame.
i) Character Count:
ii) Flag bytes with byte/character staffing
iii) Starting and ending flags, with bits staffing
iv) Physical bye coding valuations.
II.  Physical addressing : header is adding to frame.
III. Flow control
IV. Error control
V. Access control

3.Network Layer:

     Responsible for source to destination delivery of packets.
Function:
I.  Logical Addressing: header to the packet coming  from upper.
II.Routing :

4. Transport Layer:

    Responsible for process to process delivery.
Function:
I.Service point  addressing: it is a Port address at which that particular Application is running.
II. Segmentation and reassembly: it is in this massage is dividing in to segmentation segment. and reassembly is reassemble to divided  massage. Segmentation is work on sending side and reassembly work on receiving side.
III.Connection control : it is divided in two type i) connectionless ii)connection oriented.
IV.Flow and Error Control.

5.Session Layer:

Function:

I.Dialog Control: it is divided in two type i) half Duplex(one way at a time) ii) Full Duplex(two ways at a time)
II.Synchronization:it is adding checkpoints

6.Presentation Layer:

 it deals with  the syntax and semantics of the information exchanged between two systems.

 Function:

I.Translation    : converting a massage to compatible bit stream.
II.Encryption   : the translation of data into a secret code. Encryption is the most effective way to        achieve data    security. Converting plaintext to cipher text and encryption work from sending side.
III.Decryption : Decryption is converting cipher text to plaintext and Decryption work from receiving side.
IV.Compression : reducing number of bits contained in the information. It is divided in two type :
i)Lossless : in this type if you have compress the file or document  then no change  in file/document quality.
ii)Lossy : in this type if you have compress  the file or document then quality has been change.

7.Application Layer:

 Application Layer is the Protocol Data unit(PDU) at this Layer is just call the Data. Application layer is a software’s which interact human with each other. It enable the users human and software to access the network. (Example: Web Browser, yahoo massager).

Functions:

I. Network virtual Terminal: software version of physical terminal (remote host login is facilitate providing)
II.file transfer access and management
III.email services
IV.Directory services
(Note: data transfer with including header  it’s call Encapsulation and  data transfer without header it's call Decapsulation)




Summary:

Open system interconnection 

Application layer: The software which one human to another. (Web browsers)

presentation: Representation of data(Image,Video,Audio,Text)

session:Which creates and maintain the session.

transport:End to End delivery of data(TCP/UDP) Segment

Network:source IP address Destination IP Packet Router, L3 Switch

Data Link : Source Mac Address | Destination MAC Frame Switch

Physical : Encoding | Decoding