OSI Model

today my topic is OSI model this video is much longer than my other videos even though I try to simplify it OSI model is very useful too for learning and understanding about network technologies and a protocols it's a great model at explaining how data flows between natural hosts and what a row of protocols play in the data transmission process so please bear with me OSI model has seven layers starting from Malaya salmon application presentation session transport network data link and physical here are some tricks to help you to remember this is seven layers from layer 7 to layer 1 you can use this mnemonic all people same to need Domino's Pizza all people seem to need Domino pizza or you can use this one all people should try new dr.pepper all people should try new dr. pepper you can use one of them whatever works for you from layer 1 to layer Sammy you can try this trick please do not through sausage pizza away all right please do not through sausage pizza away it's gonna be all about food and a drink now let me demonstrate how data flows through the each of the seven layers of the OSI model when the client makes request to the server and in the server replies to the client eight is it generated at application-layer on the client-side trail was down the stack to presentation session transport network datalink anything physical painter through the network media data chair was to the physical layer on a server side then up to data Link Network transport session presentation and application when the server response server data goes down from a top layer application to presentation all the way to the physical layer and attained through the network media all the way to the client-side and the danger was from physical layer data link layer all the way to the top layer application thus completing one round-trip the round-trip of how data flows through all these seven layers on both sides is a physical path on which data actually and physically flows keep in mind the OSI model also addresses another important aspect how data flows on a logical path layer two layer communication for example the sender's application layer generates with data while the receivers application layer rays data the same does the presentation layer encrypts and a compresses the data while the receivers presentation layer decrypt and a decompresses data the same as the transport layer chops up a data into segments while the receivers transport layer put all these segments together the Sandra's network layer make a package while the receivers network alia opens the package and at the sender's data link layer makes the frames why the receivers declare opens frames now let me talk about OSI model layer by layer let me start with the layer seven application in non-technical terms application layer is about users application such as Firefox Chrome or Safari for website or Microsoft Outlook for email technically this application layer refers to application protocols such as HTTP for web pages and SMTP pop3 imap4 for email those protocols facilitate communications between your application and your operating system application data is generated here Leigha six presentation layer the presentation layer provides a variety of coding and conversion functions on application data these functions ensure that information sent from application layer or client would be understandable and comprehensible by the application layer of the server to put it simply this layer is try to translate application data into a certain format that every different system could understand for example if I send a picture to my friend's computer I must use some standard formats like gif or PNG so that my friends computer could understand if I want to share videos in YouTube I must to use a standard format like mp4 or AV I've another example as a professor of university I wasn't Mary in Lambeth Kansas I must speak English or elicit English otherwise my students would complain if I use an irregular shape to represent application data presentation Lee would it change it to a square which everyone is familiar with fearful the main function of this layers protocols are basically about data conversion data encryption and a data compression layer file session layer the best example to explain this layer is a telephone call in which first you establish the connection then start a composition and they terminate the session thus the major function of this layer is simply establish manage and terminate connection between the sender and the receiver without this layer the data would not go any further layer 4 transport layer transport layer accepts the data from the session layer and it chops up the data into smaller segments and add heavy information such as destination port number source port number and a sequence number which is used by the receiver to put the segment's back in order and assemble them the main protocols in this layer are TCP and UDP in a separate video I will talk about their difference in but here we only needed to know that TCP is a dominant protocol why is the transport layer completes its job this segments are moving to layer 3 network the Internet Protocol or IP the primary protocol at Network layer takes the segment's and as actual header information such as sender's IP address and receivers IP address thus packets are created network layer is all about IP addressing and IP routing without this layer parties will never travel to any other networks receivers IP address is like a receivers mailing address on an envelope without it your letter will never be delivered to the destination layer to data link layer when the IP packets arrive at this layer more header information such as source and a destination MAC address is added to each packet Fila FCS is also attached to the end of the packet altogether Ethernet frames are created MAC addresses physical address for your network interface card or NIC add this layer NIC has a crucial job of creating frames on the same side and reading or destroying frames on the receiver side last but not least layer physical layer protocols add a physical layer accepts frames from the data link layer and a generate bits and face bits are made of electrical impulses or light depending on whether the copper wires or fiber optic is used through the network media the data travels to the receiver thus completing a whole journey of with seven layers on the sender side keep in mind that OSI model is not a Balazs or physics is only a guideline whilst many protocols fit neatly into one of the seven layers others do not but OSI model is a great tool to learn and understand how Network hosts communicate with each other any series network professionals and students should know I hope this video is helpful and thank you very much andis you next time [Music]

Channel: Sunny Classroom

Views: 153,529

Keywords: sunny sun sunnysunkansas sunnyclassroom, networking, cybersecurity, security+, networking +, cyber threats, cyber defense, IoT, Wi-Fi security, OSI model, sunny classroom, sunny sun, USM, University of Saint Mary

Id: nFnLPGk8WjA

Length: 12min 13sec (733 seconds)

Published: Sun Feb 18 2018