OSI Layers In OSI Model: Simple Guide In 10 Points


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

OSI layers and functions

  1. Physical Layer in the OSI Model
  2. Data-Link Layer in the OSI Model
  3. Network Layer in the OSI Model
  4. Transport Layer in the OSI Model
  5. Session Layer in the OSI Model
  6. Presentation Layer in the OSI Model
  7. Application Layer in the OSI Model
  8. OSI model with protocols
  9. OSI layers and devices
  10. OSI layers attacks

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:

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

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 LayerFrame Creation  Transport → Transfer Frames Between Network Nodes

Data-Link Layer Functions:

  1. It adds logical locations of the receivers and sender.
  2. It additionally offers a framework for mistake control wherein it recognizes retransmits harm or lost frames.
  3. 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 LayerPackets Creation  Transport → Packets Assembly

Network Layer Functions:

  1. Its protocols to figure out which route is reasonable from source to destination.
  2. It breaks portions from the transport layer into more modest units.
  3. 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 LayerSegmentation  Transport → Reassembly

Transport Layer Functions: 

  1. It ensures that the message is conveyed to the correct interaction on the destination machine.
  2. It directs the sequencing, size, and eventually the transfer of data between hosts and systems.
  3. 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 LayerSession of Communication

Session Layer Functions:

  1. It additionally permits an interaction to add a checkpoint to the steam of data.
  2. It empowers two frameworks to go into a dialogue.
  3. 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 LayerEncryption  Compression → Translation

Presentation Layer Functions:

  1. It causes you to encode data for security purposes.
  2. Diminishes the number of bits that should be transmitted to the network.
  3. 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 LayerReturn Content in Required Format   Website

                                        Request Content   Website

Application Layer Functions: 

  1. This layer gives different email services.
  2. Network Virtual Terminal.
  3. 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


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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