DCN - Computer Network Models

Models in Computer Networking

Software, firmware, chip level engineering, hardware, and electric pulses all play a role in networking engineering. The entire networking idea is separated into numerous levels to make network engineering easier. Each layer is responsible for a certain task and is independent of the others. However, practically all networking operations rely on all of these levels in some way. Layers share data and rely on each other solely to accept and deliver input and output.

Layered Tasks

• One entire network process is separated into discrete jobs in the layered architecture of the Network Model. 
• Each little job is then allocated to a layer that works meticulously to complete the assignment alone. Each layer is responsible for only one type of task.
• One layer of a host deals with the work done by or to be done by its peer layer at the same level on the remote host in a tiered communication system. 
• The work is started at the lowest level by a layer or at the highest level by a layer. If the top-most layer initiates a job, it is sent to the layer below it for processing. 
• The lower layer performs the same thing as the upper layer; it processes the task and then sends it on to the lower layer. If the job is started by the lowest layer, the process is reversed.

Layered Tasks

• Every layer clubs together all procedures, protocols, and methods which it requires to execute its piece of task. All layers identify their counterparts by means of encapsulation header and tail.

OSI Reference Model

• Open System Interconnection (OSI) is a reference model that specifies how information from one computer's software application passes across a physical media to another computer's software application.
• The OSI is made up of seven levels, each of which serves a different network function.
• The International Organization for Standardization (ISO) established the OSI model in 1984, and it is currently used as an architectural paradigm for inter-computer communications.
• The OSI model breaks down the process into seven smaller, more achievable steps. Each layer is given a certain duty.
• Each layer is self-contained, allowing each layer's tasks to be completed individually.

OSI Model

Let's discuss about OSI Model in detail....

OSI Layered Working

1. Application Layer: This layer is responsible for providing interface to the application user. This layer encompasses protocols which directly interact with the user.
2. Presentation Layer: This layer defines how data in the native format of remote host should be presented in the native format of host.
3. Session Layer: This layer maintains sessions between remote hosts. For example, once user/password authentication is done, the remote host maintains this session for a while and does not ask for authentication again in that time span.
4. Transport Layer: This layer is responsible for end-to-end delivery between hosts.
5. Network Layer: This layer is responsible for address assignment and uniquely addressing hosts in a network.
6. Data Link Layer: This layer is responsible for reading and writing data from and onto the line. Link errors are detected at this layer.
7. Physical Layer: This layer defines the hardware, cabling wiring, power output, pulse rate etc.

Click here for Detailed study