hello everyone my name is vijay kumar Devireddy and i am glad to have you back on my episode 49 today we are discussing about The OSI Model.The Open Systems Interconnection,or OSI Model is used to explain how network communications occur between a host and a remote device over a local area network or a LAN.Now the OSI Model is very useful to help use categorize different communication protocols that are used in networks,and gives us a common lexicon that we can use to use to describe the functions of different devices.you probably remember the pneumonic of Please Do Not Throw Sausage Pizza Away.This represents the seven layers of the OSI Model,going from the bottom to the top.This is: Physical, Data Link, Network, Transport,Session, Presentation, and Application.The first layer is the physical Layer.This is the layer that represents the actual network cables and radio waves that are used to carry data over a network.Data carried over the network at the Physical Layer is known as bits.And they can be electrical signal or radio wave.Examples of some of the things that operate at the Layer One or Physical Layer,are the things like our network cables whether they're fiber optic,or copper, or coaxial.It could be radio waves like Wi-Fi and Bluetooth.It can be a hub or repeater,which are dumb devices that simply take inputs in and then repeat them out the other side.Our second layer is the Data Link Layer.This is the layer that describes how a connection is established, maintained and transferred over that physical layer.Addressing here is done using physical addresses.Like MAC addresses.Now, at this layer the bits are going to be grouped into frames and then sent over the network.Examples of some things that operate at Layer Two or the Data Link Layer, includes things like MAC addresses,switches and bridges.Now, bridges are an earlier device that have later on evolved into switches.Switches use MAC addresses as their form of physical addressing.This allows a switch to decide where to send that frame of information based on the MAC address it's designed to go to.And so, it's smarter than a hub because it will decide where that particular frame goes as opposed to just repeating it out every single port that it has.Now, as we move up the ladder we get to the third layer which is the Network Layer.This is the layer where logical addressing is actually performed.And this includes things like routing and switching information between hosts, the network and the internetworks.At this layer, the frames are now taken and grouped up into packets, so bits became frames, frames become packets.Now, examples of this include things like the addresses which are IP addresses.This allows us to tell where a piece of information,where a packet is going to be sent over our network.We also use things like Layer Three switches,which in addition to using MAC addresses to decide where things go,they can use the IP addresses at Layer Three.And of course routers which are by far the most common Layer Three device,because they're used to connect all of our networks together around the world.Our fourth layer is the Transport Layer.This layer manages and ensures transmission of the packets occur from the host to the destination it wants.This uses either a TCP, known as a Connection Full Protocol or UDP which is a Connection Less Protocol.You might remember from Network+,TCP has that three way handshake,and it says, hey I'm ready to send you something,okay I'm ready to be sent something.All right, let's start sending it.And then they send the information. --- This episode is sponsored by · Anchor: The easiest way to make a podcast. https://anchor.fm/app