Showing posts with label system. Show all posts
Showing posts with label system. Show all posts

Wednesday, 10 September 2014

OSI MODEL for Networking.

       
The International Organization for Standardization (ISO) developed the Open System Interconnection (ISO) reference model.OSI model is most widely used for networking.OSI is a seven layer standard.
          OSI model does not specify the protocols required to be used to perform networking tasks but is a model for understanding and designing a network architecture.
The Seven layers of OSI model are as follows :
1. Physical Layer : It is the lowest layer of the OSI model.It co-ordinates the functions required to transmit a bit stream over a communication channel.
Functions of Physical layer:
-Physical characteristics of interface and media.
-Representation of bits.
-Data rate.
-Synchronization of bits.

2. Data link layer : This layer is responsible for transmitting frames from one node to another.
Functions :
-Framing.
-Physical Addressing.
-Flow control.
-Error control.
-Access control.

3. Network Layer : This layer is responsible for delivery of packets from source host to destination host.
Functions :
-Logical Addressing.
-Routing.

4. Transport Layer : This layer is responsible for delivery of messages from one process to another.
Functions: 
-Port addressing.
-Segmentation and reassembly.
-Flow control.
-Error control.
-Connection control.

5. Session Layer : This layer is responsible for dialog control and Synchronization.
Functions:
-Dialog Control.
-Synchronization.

6. Presentation Layer : This layer deals with the syntax and semantics of the information being exchanged.
Functions : 
-Translation.
-Encryption.
-Compression.

7. Application Layer : This layer is responsible for accessing the network by the user.
Functions :
-Network virtual terminal.
-Mail services.
-Directory services.
-File transfer,Access and management(FTAM).
 
These are the different layers present in the OSI Model and their associated functions.

Thank you for reading.
Vishwesh Wali from India.

Thursday, 17 October 2013

Some of the important abbreviations

              
 * www : World Wide Web
 * http : HyperText Transfer Protocol
 *html : HyperText Markup Language
 *GPRS : General Packet Radio Service
 *ISP : Internet Service Provider
 *IP : Internet Protocol
 *WAP : Wireless Application Protocol
 *GSM : Global System for Mobile communication
 *CDMA : Code Division Multiple Access
 *TTL : Transistor-Transistor Logic
 *ISI : Inter Services Intelligence
 *RAW : Research and Analysis Wing
 *STD : Standard Trunk Dialling
 *ISD : International Subscriber Dialling
 *PCO : Public Call Office
 *ATM : Automated Teller Machine
 *RTO : Regional Transport Office
 *PAN : Permanent Account Number
 *URL : Uniform Resource Locator
 *USB : Universal Serial Bus 
 *CCTV:Closed Circuit Television
 *BESCOM : Bangalore Electricity Supply Company limited
 *BHEL : Bharat Heavy Electricals Limited.
 *BEL : Bharat Electronics Limited.
 *BWSSB : Bangalore Water Supply and Sewerage Board.
 *SSLC : Secondary School Leaving Certificate.
 *HDFC : Housing Development and Financial corporation.
 *HSBC : Hongkong and Shanghai Banking Corporation.
 *UPA : United Progressive Alliance
 *NDA : National Democratic Alliance.
 *SIM : Subscriber Identity Module.
 *ADSL : Asymmetric Digital Subscriber line.
 *PNR : Passenger Name Record.
 *CCV : Card Code Verification.
 *CVV : Card Verification Value.

Meaning of Top level domains in Domain Name System of internet: .com was one of the first Top Level Domain of the Domain Name System of internet.Here is a list of some common suffixes used in various websites with its meanings.

.com - Commercial Enterprise
.co.in - company specifying country as India
.nic - National Informatics centre
.edu - college level educational institution
 .gov - government website
 .mil - for military
 .org - not for profit organization
 .net - entity involved in net infrastructure such as ISP