Network Models

-

 Layering: Divides a task into sub-tasks and then solve each sub-task independently.

Advantages of layering:

  • Extensibility.
  • Facilitates modular engineering.
  • Accelerates evolution.
  • Simplifies teaching and learning.
OSI Model (Open System Interconnection Reference Model): It is a description for layered communications and computer network protocol and transmission design. It is also referred to as OSI Seven Layer Model.


Layers and its functions:
1. Application: Gives access to network resources.
                                     Protocols: SMTP, HTTP, FTP.

2. Presentation: Translates, encrypts and compresses data.
                           Protocol: MPEG, ASCH, SSL.

3. Session: Ensures establishment and termination of the session.
                   Protocol: NetBIOS, SAP.

4. Transport: Enables data transport from source to destination machine.
                      Protocol: TCP, UDP.

5. Network: Provides internetworking and packet movement.
                     Protocol: IPV5, IPV6, ICMP.

6. Data link: Organizes bits into frames.
                     Protocol: RAPA, PPP, ATM.

7. Physical: Provides mechanical and electrical specifications.
                    Protocol: RS232, ISDN, 100BaseTX.

TCP/IP Model: It is a communication protocols used to interconnect network devices on the internet.

The TCP/IP protocol suite was defined as having four layers:
  • Host-to-network: Bottom layer of TCP/IP model which connects host to the network.
  • Internet: Delivers IP packets to their destinations.
  • Internet Protocol: Transports data in packet called datagrams.
  • TCP: A transport layer that controls error, controls flow and does the sequencing.
OSI model vs TCP/IP model:

UDP (User Datagram Protocol): 
  • It is a transport layer that is used to establish low-latency and loss-tolerating connections between applications on the internet.
  • Useful in real time data transfer and quick transfer for large data

Similarities between OSI & TCP/IP:
  • Both are based on the concept of a stack of independent protocols.
  • Functionality of layer is roughly similar.
  • Up to Transport - network oriented.
  • Above - User oriented.
 Differences between OSI & TCP/IP:





 



Comments

Post a Comment

Popular posts from this blog

Basic structures of a computer

-
Image
 Computer System  A computer system consists of input. processing and output components which are also the basic functions of a computer system. Input is a place or a device through which energy or information enters a system. Input devices are keyboards, mouse, microphone and many more. Processing consists of CPU that executes instructions from the computer programs. CPUs are composed of two or more processors known as cores. Multicore CPUs enables computers to carry out instructions which leads to a better performance. Output is a place or a device which produces or delivers data. Output devices are monitor, printers, headphones, projectors and many more. Storage Components The two main category of storage are short-term storage and long-term storage. Random Access Memory (Short-term memory) RAM is a temporary memory where the data stored must be retrieved within a short span. It is also referred to as 'working storage'. A disk drive (Virtual memory) is used when there is no...
Read more

Client Server Architecture

-
Image
 Client Server architecture is an architecture or model of a computer network in which many clients request and receive service from a central server. Client computers: provides an interface to allow a computer user to request services of the server and to display the results the server returns. Servers: waits for request to arrive from clients and then respond to them. Client: It can be any computer that requests something from the server. Example: visiting any website we request the webpage from its domain.   Server: It is a computer that is designed to serve the request to the client. Example: the client asks for the webpage then the server responds with the webpage to the client.                                                        Working of Client-Server architecture The client submits a request through a network-enabled device. Th...
Read more

Fetch, execution and IO

-
Image
 The heart of the computer is the CPU which is also known as the Processor. It includes the arithmetic and logic and control in the system bus. Data is stored in bits. One byte is equivalent to eight bits. Computers interpret our intentions and process information by the representation of those instructions as bit. Process of storing data User types a character. Keyboard converts the character into binary code. All the processing and storing are done in binary form. Transmission to the printer is in binary form. Printer converts binary code to characters before printing. Functional units It is organized into words of typically 32 bits which contains 8-bit bytes. A personal computer memory might have 4 gigabytes or more. Cache memory: It is an adjunct to the main memory which is smaller and faster. It holds the sections of data and program currently/frequently bring executed. (Functional units) Processor: Logic circuits: for performing arithmetic and logic operations on word-size da...
Read more