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We have developed networking as a way to share resources and information and how that's achieved directly



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maps to the particular architecture of the networking operating systems that we have been using.



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Now, in this lecture, we are going to talk about the most common known application architecture,



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that is peer-to-peer architecture.



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There are two main network types that you need to know about.



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The first one is peer to peer, and the second one is client to server, which are going to see in the



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next lecture.



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And by the way, it's really tough to tell the difference just by looking at the diagram or even by



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checking out like the video of the network, but the differences between peer-to-peer and blind.



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So architectures are pretty major, that they are not just physical differences, they are logical differences,



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too.



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Now, you'll see what I mean in a bit.



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So what is a peer to peer network architecture?



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Well, computers connected together in peer to peer architecture do not have any central or special



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authority that all peers, meaning that when it comes to authority, that all equals, for example,



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your group of friends.



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Right.



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No one has the authority to judge you or to decide who is greater.



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But when a teacher enters a classroom, the teacher has the moral authority that is an example of clients



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of architecture.



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Then the authority to perform a security check for proper access rights lies with the computer that



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has the desired resources being requested from it.



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Now, it also means that computers existing in a peer to peer network can be applied to machines that



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access resources and server machines and provide those resources to other computers.



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Now, peer to peer network architecture is perfectly fine for less number of hosts.



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But if you're trying to have more than 50 or even 100 computers in a peer to peer network architecture,



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then it becomes a tedious task.



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If your network is running Windows, Mac or Unix in a local area network workgroup, you have to have



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a peer to peer network.



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Now, when it comes to peer-to-peer architecture, security is not centrally governed, each and every



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user has to remember and maintain a list of users and passwords on each and every machine.



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Worse, some of all those important passwords for the same users change on different machines, even



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for accessing resources.



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It's a total mess.



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And since every user has to remember the usernames and passwords of other computers, a lot of memory



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is required in this type of architecture.



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For example, as you can see on the screen.



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This is an example of peer-to-peer network architecture.



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Now, Millie, Pluto, Mickey and Louie are four types of users.



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And as you can see on the screen, each user is storing the passwords of remaining three beers.



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Now, for example, if Pluto wants to access the resources of Mickey and Mickey has to remember the



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password of Pluto, this is such a mess.



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Now, this seems okay for four computers, but what if there are hundreds, thousands of computers,



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then?



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Is it possible to store all the information in thousand computers of each and every year?



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No, that would take up a lot of time and a lot of memory.



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We do not have that much of memory just to store usernames and passwords and to tackle this problem.



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Client server architecture is.



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Used in today's most of the business applications in the next lecture will have a look at client server



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network architecture.