Which Of The Following Layers Of The Osi Model Provides Compression And Encryption Services?

What is OSI Model?

The OSI Model is a logical and conceptual model that defines network advice used past systems open to interconnection and advice with other systems. The Open up System Interconnection (OSI Model) besides defines a logical network and effectively describes reckoner package transfer past using various layers of protocols.

In this tutorial, y'all will learn:

Characteristics of OSI Model
Why of OSI Model?
What is OSI Model?
History of OSI Model
7 Layers of the OSI Model
Physical Layer
Information Link Layer
Transport Layer
Network Layer
Session Layer
Presentation Layer
Application Layer
Interaction Between OSI Model Layers
Protocols supported at various levels
Differences betwixt OSI & TCP/IP
Advantages of the OSI Model
Disadvantages of the OSI Model

Characteristics of OSI Model

Here are some important characteristics of the OSI model:

A layer should but exist created where the definite levels of brainchild are needed.
The office of each layer should be selected as per the internationally standardized protocols.
The number of layers should exist large so that separate functions should not be put in the aforementioned layer. At the same fourth dimension, information technology should be pocket-size enough then that architecture doesn't become very complicated.
In the OSI model, each layer relies on the next lower layer to perform primitive functions. Every level should able to provide services to the next college layer
Changes made in one layer should not need changes in other lavers.

Why of OSI Model?

Helps y'all to understand advice over a network
Troubleshooting is easier by separating functions into different network layers.
Helps you to sympathise new technologies as they are developed.
Allows you lot to compare primary functional relationships on various network layers.

History of OSI Model

Hither are essential landmarks from the history of OSI model:

In the late 1970s, the ISO conducted a program to develop general standards and methods of networking.
In 1973, an Experimental Bundle Switched Arrangement in the UK identified the requirement for defining the higher-level protocols.
In the year 1983, OSI model was initially intended to be a detailed specification of actual interfaces.
In 1984, the OSI architecture was formally adopted by ISO as an international standard

seven Layers of the OSI Model

OSI model is a layered server architecture system in which each layer is defined according to a specific function to perform. All these seven layers piece of work collaboratively to transmit the data from one layer to another.

The Upper Layers: Information technology deals with application issues and mostly implemented only in software. The highest is closest to the stop system user. In this layer, advice from one terminate-user to another begins by using the interaction between the awarding layer. It will process all the way to stop-user.
The Lower Layers: These layers handle activities related to data transport. The physical layer and datalink layers likewise implemented in software and hardware.

Upper and Lower layers farther carve up network architecture into seven unlike layers equally below

Application
Presentation
Session
Transport
Network, Data-link
Physical layers

Let's Study each layer in detail:

Physical Layer

The concrete layer helps you to define the electrical and physical specifications of the information connection. This level establishes the human relationship between a device and a physical transmission medium. The physical layer is not concerned with protocols or other such higher-layer items.

Examples of hardware in the physical layer are network adapters, ethernet, repeaters, networking hubs, etc.

Information Link Layer:

Data link layer corrects errors which tin occur at the concrete layer. The layer allows y'all to ascertain the protocol to establish and terminates a connexion between two connected network devices.

It is IP address understandable layer, which helps y'all to define logical addressing and so that any endpoint should be identified.

The layer also helps you implement routing of packets through a network. It helps you lot to ascertain the best path, which allows you to take data from the source to the destination.

The information link layer is subdivided into two types of sublayers:

Media Access Command (MAC) layer- It is responsible for controlling how device in a network gain access to medium and permits to transmit data.
Logical link control layer- This layer is responsible for identity and encapsulating network-layer protocols and allows yous to notice the error.

Important Functions of Datalink Layer:

Framing which divides the data from Network layer into frames.
Allows yous to add header to the frame to ascertain the physical address of the source and the destination machine
Adds Logical addresses of the sender and receivers
Information technology is as well responsible for the sourcing process to the destination process delivery of the unabridged bulletin.
It also offers a system for error command in which it detects retransmits harm or lost frames.
Datalink layer also provides a mechanism to transmit data over independent networks which are linked together.

Send Layer:

The send layer builds on the network layer to provide data transport from a process on a source machine to a process on a destination motorcar. It is hosted using single or multiple networks, and also maintains the quality of service functions.

Information technology determines how much data should exist sent where and at what rate. This layer builds on the message which are received from the application layer. It helps ensure that data units are delivered fault-free and in sequence.

Transport layer helps yous to control the reliability of a link through flow control, error control, and segmentation or desegmentation.

The ship layer as well offers an acknowledgment of the successful information transmission and sends the next data in case no errors occurred. TCP is the best-known example of the transport layer.

Of import functions of Transport Layers:

Information technology divides the bulletin received from the session layer into segments and numbers them to make a sequence.
Send layer makes sure that the message is delivered to the correct process on the destination machine.
It besides makes certain that the entire bulletin arrives without any mistake else it should exist retransmitted.

Network Layer:

The network layer provides the functional and procedural means of transferring variable length data sequences from one node to another connected in "different networks".

Bulletin commitment at the network layer does non give whatsoever guaranteed to be reliable network layer protocol.

Layer-management protocols that belong to the network layer are:

routing protocols
multicast grouping management
network-layer address assignment.

Session Layer

Session Layer controls the dialogues between computers. Information technology helps yous to establish starting and terminating the connections betwixt the local and remote application.

This layer request for a logical connection which should exist established on end user'south requirement. This layer handles all the important log-on or password validation.

Session layer offers services similar dialog discipline, which tin be duplex or half-duplex. It is mostly implemented in application environments that use remote process calls.

Of import part of Session Layer:

It establishes, maintains, and ends a session.
Session layer enables two systems to enter into a dialog
It also allows a process to add a checkpoint to steam of data.

Presentation Layer

Presentation layer allows you to ascertain the grade in which the information is to exchange between the two communicating entities. Information technology also helps you to handles data compression and data encryption.

This layer transforms information into the form which is accepted by the application. It also formats and encrypts information which should exist sent across all the networks. This layer is also known as a syntax layer.

The function of Presentation Layers:

Character code translation from ASCII to EBCDIC.
Data compression: Allows to reduce the number of bits that needs to be transmitted on the network.
Data encryption: Helps you to encrypt information for security purposes — for instance, password encryption.
It provides a user interface and support for services like e-mail and file transfer.

Application Layer

Awarding layer interacts with an application program, which is the highest level of OSI model. The awarding layer is the OSI layer, which is closest to the terminate-user. It means OSI application layer allows users to interact with other software application.

Application layer interacts with software applications to implement a communicating component. The interpretation of data past the application programme is always exterior the scope of the OSI model.

Example of the application layer is an application such as file transfer, e-mail, remote login, etc.

The role of the Application Layers are:

Application-layer helps you to identify communication partners, determining resource availability, and synchronizing communication.
It allows users to log on to a remote host
This layer provides various due east-mail services
This application offers distributed database sources and access for global information most diverse objects and services.

Interaction Between OSI Model Layers

Data sent from a one computer application to another needs to laissez passer through each of the OSI layers.

This is explained in the beneath-given case:

Every layer within an OSI model communicates with the other two layers which are below it and its peer layer in some another networked computing system.
In the below-given diagram, you tin see that the data link layer of the first organization communicates with 2 layers, the network layer and the physical layer of the system. It also helps y'all to communicate with the information link layer of, the second system.

Layers of OSI Model

Protocols supported at various levels

Layer	Proper name	Protocols
Layer vii	Awarding	SMTP, HTTP, FTP, POP3, SNMP
Layer 6	Presentation	MPEG, ASCH, SSL, TLS
Layer 5	Session	NetBIOS, SAP
Layer 4	Transport	TCP, UDP
Layer three	Network	IPV5, IPV6, ICMP, IPSEC, ARP, MPLS.
Layer 2	Data Link	RAPA, PPP, Frame Relay, ATM, Fiber Cablevision, etc.
Layer 1	Physical	RS232, 100BaseTX, ISDN, 11.

Differences between OSI & TCP/IP

Layers of OSI Model

Hither, are some important differences between the OSI & TCP/IP model:

OSI Model	TCP/IP model
OSI model provides a articulate distinction between interfaces, services, and protocols.	TCP/IP doesn't offering whatever clear distinguishing points between services, interfaces, and protocols.
OSI uses the network layer to define routing standards and protocols.	TCP/IP uses just the Internet layer.
OSI model use 2 separate layers physical and information link to define the functionality of the lesser layers	TCP/IP uses only i layer (link).
OSI model, the send layer is but connection-oriented.	A layer of the TCP/IP model is both connection-oriented and connectionless.
In OSI model, information link layer and physical are divide layers.	In TCP data link layer and concrete layer are combined as a single host-to-network layer.
The minimum size of the OSI header is 5 bytes.	Minimum header size is xx bytes.

Advantages of the OSI Model

Hither, are major benefits/pros of using the OSI model :

It helps you to standardize router, switch, motherboard, and other hardware
Reduces complexity and standardizes interfaces
Facilitates modular engineering
Helps you to ensure interoperable engineering
Helps yous to accelerate the evolution
Protocols can be replaced by new protocols when technology changes.
Provide support for connection-oriented services as well equally connectionless service.
It is a standard model in reckoner networking.
Supports connectionless and connection-oriented services.
Offers flexibility to adapt to various types of protocols

Disadvantages of the OSI Model

Here are some cons/ drawbacks of using OSI Model:

Fitting of protocols is a tedious task.
You can only utilise it as a reference model.
Doesn't define any specific protocol.
In the OSI network layer model, some services are duplicated in many layers such as the transport and data link layers
Layers tin can't piece of work in parallel as each layer demand to expect to obtain data from the previous layer.

Summary

The OSI Model is a logical and conceptual model that defines network communication which is used by systems open up to interconnection and advice with other systems
In OSI model, layer should only be created where the definite levels of abstraction are needed.
OSI layer helps you to understand advice over a network
In 1984, the OSI compages was formally adopted by ISO as an international standard

Layer	Proper noun	Function	Protocols
Layer seven	Application	To allow access to network resource.	SMTP, HTTP, FTP, POP3, SNMP
Layer 6	Presentation	To interpret, encrypt and shrink data.	MPEG, ASCH, SSL, TLS
Layer 5	Session	To establish, manage, and terminate the session	NetBIOS, SAP
Layer iv	Transport	The transport layer builds on the network layer to provide data ship from a procedure on a source machine to a process on a destination machine.	TCP, UDP
Layer three	Network	To provide internetworking. To move packets from source to destination	IPV5, IPV6, ICMP, IPSEC, ARP, MPLS.
Layer 2	Data Link	To organize bits into frames. To provide hop-to-hop commitment	RAPA, PPP, Frame Relay, ATM, Fiber Cablevision, etc.
Layer 1	Physical	To transmit $.25 over a medium. To provide mechanical and electrical specifications	RS232, 100BaseTX, ISDN, 11.