In the last blog , we saw what the OSI Layers .Now its time to see what each layer is ,in short
A) Application Layer-It is employed in software packages which implement client-server software. When an application on one computer starts communicating with another computer, then the Application layer is used.
B) Presentation Layer-This provides function call exchange between host operating systems and software layers. Mostly dealing with compression ,encryption and decryption
C) Session Layer-The Session layer defines how data conversations are started, controlled and finished. It allows to create dialog between the systems .
D) Transport Layer - Ordering and reassembling of packets that may have been broken up to travel across certain media. It guaranties that the packet reached the destination successfully.
E) Network Layer- Mostly, the routing of packets is done here. Responsible for the delivery of packets end to end and implements a logical addressing scheme to help accomplish this.
F) Data Link Layer - Its divides the packet into frames and provide error correction by adding a trailer bit to the frame.
G) Physical Layer--This layer deals with the physical aspects of the media being used to transmit the data. Deals with the conversion of data bits into electric signals , their transmission and synchronization .
This can be easily memorized by
" ALL PEOPLE SEEMS TO NEED DATA PROCESSING"
hope u understood and Best of Luck.
keep looking....
OSI, Open Systems Interconnection model ,is open standard for communication among two systems. OSI model was developed " Charles Bachman " which evolved to remove various difficulty faced in ARPANET. If you are interested ,the actual document is available free of cost at
TU-T/X.200-series of recommendations
or
http://www.itu.int/rec/T-REC-X.Imp200-200612-I/en
The Open System Interconnection (OSI) model is a set of protocols that attempt to define and standardize the data communications process. Its divides the communication channel into 7 layers ,each layer performing its own functionality. Numerous protocols at each layer provide security and encapsulation . each layer is at the top of another and transfer data to each other from SAP ( service access protocol)
The figure below show us the 7 layers of OSI
As in the figure the last three layers are grouped as "Media layers" and the upper four as "Host Layers". Media layers are mainly responsible for transferring the data through the physical medium ( converting the data into bit streams , synchronizing it, etc) where as the host layer is mainly focused on how the data is to be represented and various applications interfaces.
NOTE: Segment and Presentation Layers are usually not very useful and hence were removed in TCP/IP MODEl.
hope u understood and Best of Luck.
keep looking....
