OK.
So we're going to discuss a little bit about what a network is.
First of all and there isn't much that an work isn't.
Once we know what the network is just as a background now a network basically just means that we have
a bunch of nodes and we have a bunch of ways to connect those notes.
OK so there we go.
We have something like this.
Now we can have information that we're sending across the network that could be one thing.
OK we have edges and you know we don't need all the technical things but we have edges right there and
we send information possibly what else could we send the kids and info we can send water.
We can send electricity right.
We can have a network of electricity that is being going from one place to another.
We can have water that is traveling from one place to another we can have like we said any various form
of information it's traveling and it doesn't need to be that it has to be on a wire it could be that
someone is telling somebody else like a social media network.
OK.
Networks have a lot of applications now.
The point being that there is a vast array of them and there's a lot of different things that we might
be thinking about when we think about networks.
But but the mathematics of it is is an important part of it as well which is to say what rules do you
have for your network.
For instance if you talk about electricity you may be have some big pipes which lead into.
Or big wires or pipes whatever you're talking about which lead into smaller ones.
And it could be that they're not allowed to go backwards.
Right it could be that it's not allowed.
It's only going to go one way versus maybe if you're sending information you can have protocols which
go two ways.
So we have to figure out something very important which is what are the protocols.
To this in other words what are the rules systems that we're going to have if I send you information.
How long should I wait to see if you've got it.
Should I.
Do you have to respond to me that you got it or can you.
Can I just assume that you got it.
Should I send it three times just to make sure that everything is going the way that it should be.
Or is that not the case.
So Protocols are a very important part of network of K networks the definitions of how the network works
is also extremely important.
Other words like we said does it only go one way but sometimes it can go both ways.
Maybe this one can go both ways but this one can only go one way doesn't have to be that everybody in
the network connects.
What is the topology of the network.
Is it that everybody connects in every way possible like this.
Kate Kate and graph and graph theory.
Or is it that that's not everybody connects and then they're going to have people on the outside over
here that you know have to connect in other ways do you want to connect like this where everybody connects
in that fashion or do you want to have something where everybody connects to an inner node in the inside
that way.
Now what are the differences.
Well it depends what information we have and you can see obviously if the Internode goes out the rest
do over here.
If one of these goes out the other it could talk that way possibly but maybe not depending on the system.
So there's a lot of questions that we might have about networks and but mathematically we can define
these and explain these and do what we have problems in mathematics about traversing a network.
OK.
Can I get from one point to the other.
OK.
Can I get from one point to the other without ever go with touching every node once right.
Because we're sending information we don't want to be redundant.
Can I do it with only touching every edge once.
OK so if I reverse this I was able to touch Let's say every node.
Can we do that let's say I'll go here here here here here here.
OK I touched every note and I got back to where I was what about every edge can I do that doesn't seem
that way in this graph.
Right.
So we can ask those questions which are you know quite important whether we're talking about train schedules
whether we're talking about you know transportation routes in you know for a company all these different
things now in networks in computers we have something called the oocyte model there are seven layers
we have the physical datalink network transport session presentation and application.
OK.
The physical layer is the bottom layer that has to do with what's going on inside the computer we're
going to be discussing a lot of those things zeros and ones how was transferring information and changing
it.
The datalink layer a reliable Directorate.
Points point connection with the network.
Each layer has security involved in it.
Each layer has different protocols involved in it.
Each layer has different jobs.
Each layer does different things you can have the packaging.
You can have eccentricities of addressing routing delivery of datagrams between networks and a point
to point and so that's the network layer.
So we're going to be discussing each of these you have the transport layer that's getting from one place
to another.
These of course are going to be stuff we'll discuss the session application presentation layer or completely
different area wise separate into several different layers as well because then each person can you
know in a group could work on these all separately and then you'd have less issues with you know with
dealing with things.
If we if we isolate each concept and then you know deal with it separately so it is a very good thing
that we do that so you can you know get the information you can you know package the information you
can give it you can give it you know an address and all that stuff you can send it along on the routes
etc. and then you can have protocols for sending it along the route and transferring it and getting
information from point A to Point B as we can see.
You've got to package information you've got to give it the right route.
You've got to give it you know all this stuff goes into network.
What's the route this is going to take.
Is it going to take route little they route little B.
Well if it takes a little they that would be quicker if it takes with little B that would be slower.
How do we decide what we take.
What is the package going to look like so we can assure that it got there securely.
Right that's going to be very important to get there securely can we show that.
Are there tests to identify that got there securely.
Was it packaged in an intelligent way that perhaps we can send little data packets along to the food
food food food food food these are data packets in case you're wanting to put put put.
And that's the sound that data packets or should be they be in order or can we send them and all kinds
of different orders and then to have them remade in any kind of any kind of mash up and then just remake
it at point B.
Right.
So that's the question that we're going to have to address with these with these points over here.
OK now there's other things to address here like HTP and whatever but we're going to be focusing on
these layers of physical datalink network and transport layers each of which has protocols you may have
heard of like IP Internet Protocol rights.
You know you have stuff like then there's different versions of things that you can have.
So for instance we have these numbers that you would look up 1 6 8.
That that that that that you know and then we have names that you need and we have all kinds of different
steps that go into this in order to ensure that every step along the way everybody agrees.
We both agree on the same protocols in other words we both know exactly what's happening so nobody gets
confused about what something means etc. and then we all have the same systems in order to do that.
So for instance if we send that over copper wires or over optical wires etc. We know the data can be
managed and and retain so it's very important to think about networks not just in terms of stuff related
to computers specifically but in general we it's very important to be thinking about the rules for a
network and what it should do and what what we would need to have as protocols that we follow so that
everything will run smoothly.
So we'll be discussing the different layers.
I'm just giving you a picture right here so that way you can see it and then we'll be developing these
concepts throughout.