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OSI Layers In OSI Model: Simple Guide In 10 Points

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OSI Layers In OSI Model: Simple Guide In 10 Points

10 Mar 2021

Introduction

The OSI Model is a conceptual and logical model that characterizes network communication utilized by systems open to communication and interconnection with different systems. We will below understand various OSI layers and its functions.

The Open System Interconnection or OSI reference model also characterizes a logical network and adequately depicts the computer packet transfer by utilizing different protocols.

The recent Internet did not depend on Open System Interconnection, yet the less difficult TCP/IP model. Notwithstanding, the seven OSI layers model is still broadly utilized, as it envisions and imparts how networks work and help isolate and troubleshoot networking issues.

List of OSI layers

The list of OSI layers in tabular format is under:

OSI Architecture

Layer	Name of Layer
Layer 7	Application	Software/Upper Layers	Sender ↓ Receiver ↑
Layer 6	Presentation
Layer 5	Session
Layer 4	Transport	Heart of OSI
Layer 3	Network	Hardware/Lower Layers
Layer 2	Data-Link
Layer 1	Physical

1. Physical Layer in the OSI Model

The physical layer encourages you to determine the physical and electrical determinations of the data connection.

Physical OSI Layer: Sending cable → Bitstream → Receiving Cable

Physical Layer Functions:

It gives the synchronization of the bits by giving a clock.
It isn’t worried about protocols or other such higher-layer things.
It additionally determines the transmission rate.

2. Data-Link Layer in the OSI Model

The data link layer is very much like the network layer, aside from the data link layer encourages data to move between two devices on a similar network.

Data-Link OSI Layer: Frame Creation → Transport → Transfer Frames Between Network Nodes

Data-Link Layer Functions:

It adds logical locations of the receivers and sender.
It additionally offers a framework for mistake control wherein it recognizes retransmits harm or lost frames.
Framing separates the data from the network layer into frames.

3. Network Layer in the OSI Model

It works for the transmission of data from one host to the next situated in various networks.

Network OSI Layer: Packets Creation → Transport → Packets Assembly

Network Layer Functions:

Its protocols to figure out which route is reasonable from source to destination.
It breaks portions from the transport layer into more modest units.
The sender and receiver’s IP address are set in the header by the network layer.

4. Transport Layer in the OSI Model

It deals with the delivery and error checking of data packets.

Transport OSI Layer: Segmentation → Transport → Reassembly

Transport Layer Functions:

It ensures that the message is conveyed to the correct interaction on the destination machine.
It directs the sequencing, size, and eventually the transfer of data between hosts and systems.
It additionally ensures that the whole message shows up with no mistake else. It ought to be retransmitted.

5. Session Layer in the OSI Model

This layer is answerable for the establishment of connection, support of sessions, verification and guarantees security.

Session OSI Layer: Session of Communication

Session Layer Functions:

It additionally permits an interaction to add a checkpoint to the steam of data.
It empowers two frameworks to go into a dialogue.
It establishes, maintains, and closes a session.

6. Presentation Layer in the OSI Model

It permits you to determine the form in which the data is to trade between the two communicating entities.

Presentation OSI Layer: Encryption → Compression → Translation

Presentation Layer Functions:

It causes you to encode data for security purposes.
Diminishes the number of bits that should be transmitted to the network.
It gives a UI and support for services like file and email transfer.

7. Application Layer in the OSI Model

The Application Layer (7 layers of OSI Model) is the lone layer that straightforwardly interacts with data from the client.

Application OSI Layer: Return Content in Required Format → ← Website

Request Content → ← Website

Application Layer Functions:

This layer gives different email services.
Network Virtual Terminal.
It permits clients to log on to a distant host.

8. OSI model with protocols

Layer Name Protocols	Protocols
Application Layer Protocol	SNMP, POP3, FTP, HTTP, SMTP
Presentation Layer Protocol	TLS, SSL, ASCH, MPEG
Session Layer Protocol	SAP, NetBIOS
Transport Layer Protocol	UDP, TCP
Network Layer Protocol	MPLS, ARP, IPSEC, ICMP, IPV6, IPV5
Data-Link Layer Protocol	Fibre Cable, ATM, Frame Relay, PPP, RAPA, and so on.
Physical Layer Protocol	ISDN, 100BaseTX, RS232

9. OSI layers and devices

OSI Layer	Devices
Application Layer	Application Proxy Firewalls
Presentation Layer	N/A
Session Layer	N/A
Transport Layer	N/A
Network Layer	Router, Layer 3 Switch
Data-Link Layer	NICs, Bridges, Switches, Encryption Devices
Physical Layer	Modems, Repeater, Hubs, NICs, Connectors, Cables

10. OSI layers attacks

Layers	Attacks
Application Layer	Version Rollback Attack, Send Mail, FTP, and Network File System Bugs
Presentation Layer
Session Layer	Portmapper Exploits and Remote Procedure Call Worms
Transport Layer	Sequence Number Prediction, SYN Flooding, and Routing Information Protocol Attacks
Network Layer	IP Smurfing and Other Address Spoofing Attacks
Data-Link Layer	Wired Equivalent Privacy Attacks
Physical Layer

Conclusion

The types of OSI layers are a conceptual and logical model that determines network communication which is utilized by frameworks open to communication and interconnection with different frameworks.

OSI layers causes you to comprehend communication over a network.

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