Skip to main content

Networking 3 - OSI Model

To ensure worldwide data communication, systems must be developed which are compatible to communicate with each other ISO has developed a standard. ISO stands for International organization of Standardization.

OSI Model -This is called a model for Open System Interconnection and is commonly known as OSI model. The ISO-OSI model is a seven layer architecture. It defines seven layers or levels in a complete communication system.

Functions of Different Layers :
Related image

Physical layer

The Physical layer is also called as the Layer 1. Here are the basic functionalities of the Physical layer:
·         Responsible for electrical signals, light signal, radio signals etc.
·         Hardware layer of the OSI layer
·         Devices like repeater, hub, cables, ethernet work on this layer
·         Protocols like RS232, ATM, FDDI, Ethernet work on this layer

Data Link layer

The data link layer is also called as the Layer 2 of the OSI model. Here are the basic functionalities of the data link layer:
·         Responsible for encoding and decoding of the electrical signals into bits.
·         Manages data errors from the physical layer
·         Convers electrical signals into frames
·         The data link layer is divided into two sub-layers
o    The Media Access Control (MAC) layer
o    Logical Link Control (LLC) layer.
·         The MAC sublayer controls how a computer on the network gains access to the data and permission to transmit it.
·         The LLC layer controls frame synchronization, flow control and error checking.
·         MAC address is a part of the layer 2.
·         Devices like Switch work at this layer

Network Layer

The Network layer is also called as the layer 3 of the OSI model. Here are the basic functionalities of the network layer:
·         Switching and routing technologies work here
·         Creates logical paths between two hosts across the world wide web called as virtual circuits
·         Routes the data packet to destination
·         Routing and forwarding of the data packets.
·         Internetworking, error handling, congestion control and packet sequencing work at this layer
·         Router works at layer three
·         Different network protocols like TCP/ IP, IPX, AppleTalk work at this layer

Transport layer

The Transport  layer is also called as the layer 4 of the OSI model. Here are the basic functionalities of the Transport layer:
·         Responsible for the transparent transfer of data between end systems
·         Responsible for end-to-end error recovery and flow control
·         Responsible for complete data transfer.
·         Protocols like SPX, TCP, UDP work here

Session layer

The Session  layer is also called as the layer 5 of the OSI model. Here are the basic functionalities of the Session layer:
·         Responsible for establishment, management and termination of connections between applications.
·         The session layer sets up, coordinates, and terminates conversations, exchanges, and dialogues between the applications at each end.
·         It deals with session and connection coordination.
·         Protocols like NFS, NetBios names, RPC, SQL work at this layer.

Presentation layer

The Presentation layer is also called as the layer 6 of the OSI model. Here are the basic functionalities of the presentation layer:
·         Responsible for data representation on your screen
·         Encryption and decryption of the data
·         Data semantics and syntax
·         Layer 6 Presentation examples include encryption, ASCII, EBCDIC, TIFF, GIF, PICT, JPEG, MPEG, MIDI.

Application Layer

The Application layer is also called as the layer 7 of the OSI model. Here are the basic functionalities of the Application layer.
·         Application layer supports application, apps, and end-user processes.
·         Quality of service
·         This layer is responsible for application services for file transfers, e-mail, and other network software services.

·         Protocols like Telnet, FTP, HTTP work on this layer.
TCP/IP model in Next Blog

Comments

Post a Comment

Popular posts from this blog

OSSEC - Open source And Free Host Intrusion Detection System (HIDS)

As it clarify with name that it is host based intrusion detention system we need to set it up in host/server which we want to monitor. Features File Integrity checking Log Monitoring Rootkit detection Active response Benefits Compliance Requirements -  PCI and HIPAA Multi platform Real-time and Configurable Alerts Integration with current infrastructure Centralized management Agent and agentless m onitoring Configuration   I did in Ubuntu so here are commands I used  sudo apt get update -y sudo apt-get install apache2 -y sudo apt-get install build-essential -y sudo apt get update -y wget https://github.com/ossec/ossec-hids/archive/2.9.2.tar.gz sudo tar -zxvf 2.9.2.tar.gz cd ossec-hids-2.9.2/ sudo ./install.sh sudo /var/ossec/bin/ossec-control start cd /home/ubuntu wget https://github.com/ossec/ossec-wui/archive/master.zip sudo apt-get install unzip -y sudo unzip master.zip mv ossec-wui-master /var/www/html/ossec ...
Post a Comment
Read more

An Nvidia card was not detected in your system fix for Asus Laptops

This article explains how to fix issue like "NVIDIA display settings are not available" OR "An Nvidia card was not detected in your system" in your Asus laptop. The Error looks like  And GPU is not present in armory crate as well You will not be able to Nvidia driver in Device Manager as well To fix this go to your armory crate software and check if Eco mode is enabled in GPU mode. Select any other mode i.e., standard  If you do not see it in your Home Page, go to device and select GPU power saving option and select any other mode than Eco mode. As you select any other mode your GPU will be back This happens because Eco Mode Completely disables GPU for power saving from armory crate Made a video as well regarding this do check it out.
Post a Comment
Read more

OpenVAS vulnerability scanner

  OpenVAS is a framework of several services and tools offering a comprehensive and powerful vulnerability scanning and vulnerability management solution. The framework is part of Greenbone Networks commercial vulnerability management solution from which developments are contributed to the Open Source community since 2009. ·          The actual security scanner is accompanied with a regularly updated feed of Network Vulnerability Tests (NVTs), over 50,000 in total. All OpenVAS products are Free Software. Most components are licensed under the GNU General Public License (GNU GPL). ·          About NVT Feed - Greenbone maintains a public feed of Network Vulnerability Tests (NVTs) for the OpenVAS project, the Greenbone Community Feed. It contains more than 50,000 NVTs, growing on a permanent basis. This feed is configured as the default for the OpenVAS Scanner and relates to the Gr...
Post a Comment
Read more