Mike Meyers on: Intro to TCP/IP

I'm gambling that most of us out here have heard the term IP address so I'd like to start off by showing you what would be a typical IP address you might see on a computer today so here's one ninety two dot one sixty eight dot 5.10 does that look familiar to you these four digits separated by three dots what we're looking at are the addresses that help us get information to any computer on the internet without these IP addresses the Internet's not going to work but to really understand how all this started we got to go way back in time back in a time when we wanted big networks but we didn't have one yet and what we're going to start with his here in the United States here's a map of the continental United States so there there's Maine and Florida so if we got you know what wait a minute we're gonna do this live forget about it okay let's do this with me in front of you because I love talking about this stuff so here's our map in the United States I'm from Texas all right so here's what map the United States now all around the United States are military installations and there was military installations there is also a lot of universities the idea is that we had all over the United States thousands of local area networks and we wanted to interconnect these local area networks so that anybody in one land could talk to another land get the idea so we would have connections to land up here in Chicago and a land over here in San Jose land over here in Boston land down here at Rice University in Houston somewhere in northern Florida the idea here is that we would have these individual lands and we want to connect them now we're talking the late 1970s early 1980s here so these were connected through basically telephone lines back in the old days and this was being designed by an organization called ARPANET or ARPA is the same organization today and the idea is that we would create multiple connections to these individual nodes which would then act to help other know and more importantly if any of these nodes went down if this one went kaboom we could reroute this information and it would still get to everybody now the problem is is we need some kind of numbering system to organize all this now they were coming up with this numbering system back in the late 1970s early 80s and they were thinking well you know one day there could be you know 1020 thousand computers on this thing which we're eventually going to call the Internet so we need to think big yeah if they didn't think that big so basically what you have is you've got four numbers so I'm gonna say for this example I'm gonna say 10.11 dot 12.30 n-- 0 to 255 all the different combinations come up to around 4 billion addresses and back in the late 70s early 80s they go this is going to be great now keep in mind every computer on this thing which will eventually be called the Internet must have its own IP address but not just a so an IP address we're gonna have all of these lands all over the place so this number is going to do two things at the same time number one it's going to identify which local area network you're a member of and number two it's going to give you a unique what we call host ID that's unique only to you got it all right so the whole idea between taking these and breaking them into four groups with three dots is that we would have what was called tier 1 of the internet now this was the original plan and there would be some local area network here a router and he would be called the 10 router and then this router over here and Rice University in Houston would have been called the 12 router I am making these numbers up but this is basically how it happened then over here in San Jose this would be the six router well Mike why didn't they do 1 2 3 4 because they're computer nerds and they this guy over here like the number 6 there was no rules it was Wild West back then all right so this is kind of the basic idea now I'm gonna do now is I'm gonna concentrate on Rice University that's Galveston Bay there's Galveston Island this is the southeast coast of Texas here's Houston and right about here is Rice University so Rice University there's going to be twelve now the problem here is that there's a lot of people in the Houston area who also want to be connected to this thing which will eventually be called the Internet so what will happen it's a over at University of Houston University of Houston instead of connecting to the big top part they're going to get their own little router and Rice University is then going to call that router 12.1 now here's the important thing anybody who hooks to the 12 router their IP address will start with a 12 now it's up to the folks here at Rice University to delegate down to whoever needs it and back then this was all free and everybody loved each other and this stuff was easy to get so now all of a sudden University of Houston is 12.1 well there's a lot of computers at University of Houston they've got the parallel processing center they've got the engineering college they've even got an art college and I don't know those artsy types they want to have their own little local area network as well so what we're gonna do from there is we're they gonna start passing out so the parallel processing they're gonna be 12.1.0 for again nobody ever did these in order just out of cruelty I think and then over here is going to be 12.1 dot and those crazy art people well they're going to be 12.1 dot there we go now notice these numbers are all different these are all separate local area networks now we've got one more digit right well that last digit is for the individual computers so what would happen is that this one little local area network here would have the network ID of 12.1 44 and then the individual computers would be one two three four five six all the way up to 254 because you cannot use zero or 255 and in other episodes we'll explain why that happens so there is a little bit of limitation but not much so the whole idea behind the whole internet was going to be what we call aggregation and it didn't quite pan out that way because sometimes other people like another Comcast would come in and put a different kind of numbering system in but the bottom line is that it works now what's interesting is that they designed this in such a way that it had a lot of flexibility so for example if you needed an IP address oh by the way you'll just type these into your computer these are allocated to you by the internet authorized numbering authority there I am a and the idea is that no two computers on the Internet can ever have the same IP address so you don't just magically type this in somebody from on high passes you down a block of addresses so for example you would call up if you're at University Houston you'd call up the U of H people and they would allocate something 12.1 dot wondered even more than they call a price University in Rice University would give them a 12.3 or whatever was next on the list you get the idea so you always came down from on high and got yourself a block of addresses any block of addresses where the first three numbers are set and you can do anything you want on the fourth number we call those Class C if you get a block of addresses now there's another limitation here I'm going to avoid this for the moment and the first two numbers are locked it's a Class B and then if the first number is locked and you get to do whatever you want with the last three then we call it a Class A if you have a Class C address you have 254 hosts you can have in that local area network if you have a Class B you get 256 or 256 about 65,000 534 and if you've got a Class A it's in the millions so most the time the people who got Class A's were people like Rice University or somebody they knew they were going to pass it down to the bottom line is is that we live in a world where IP addresses are based on the idea that you're always going to be no more than four routers away from the top of the Internet and boy did they make a mistake there so the total address space of the IP addressing was about four billion IP addresses but the problem is a lot of them were wasted on all kinds of dumb stuff like for example no address can end with two fifty-five so that gets rid of a bunch or you would have certain addresses like anything that started with one was experimental they called it reserved and nobody could use them so there was lots of limitations for billion sounds like a lot even in today's world but it was nowhere near enough you're gonna have to watch other episodes to see how we snuck around this limitation cuz we've done a pretty good job of it right now what's important to me is that you understand the nomenclature of an IP address so let's make sure we have four characters and these characters go from 0 to 255 you will have three dots in between them and watch out on the exam they will actually have examples up where they'll have an IP address and it'll have like 257 in it or something like that and they're going to say which of these four is valid not the one with 257 also keep in mind that addresses never end with a 0 or a 255 and we'll save that for other episodes to make you understand why that exactly is with IP addressing we're gonna add something to our frame here so what I'm gonna do is now add in the destination IP address and the source IP address this is going to allow us to jump from local area network to local area network so to actually watch all this in action let's zoom in a little bit and I'm gonna concentrate on just two small local area networks that just happen to be connected together with the same router I've got two local area networks here now there's a switch in here and I'm gonna draw some computers I just like to draw a circle to show you what the network ID is inside every one of these computers I have entered a value that starts with 10.11 dot 12 dot something so we put a zero on the end to show that we're not talking about a computer we're talking about a network ID so that's one of the reasons we can't put a 0 on the end of an IP address because it identifies an entire land so this computer right here might be 10 dot 11 12 . 44 and this one right here might be 10.11 dot 12.2 22 those numbers get in there because somebody typed them in every operating system as a place for us to enter these values now over here on this other network which is 10.14 6.0 I'm just going to draw one computer in here and he's going to be 10.14 dot 6.7 so let's get some communication going now if this computer over here 10.11 dot twelve dot forty-four wants to talk to 10.11 dot 12.2 twenty-two so what's he's going to do is he's going to take a look at the IP address where he's sending it to and he's going to compare it to something called a subnet mask this is another value that you have to enter into your computer so a subnet mask usually looks something like this 255 255 255 dot 0 wherever you see a 255 the numbers have to be the same wherever you see a 0 the numbers can be different so let's compare these two addresses they're both 10.11 dot twelve and only the last digit is different correct so by looking at the subnet mask that's how your computer calculates this he knows something very important he knows that that other address is in his local area network that easy just by comparing the address he's sending it to with his own IP address that way he could go ahead and put on the proper MAC addresses and just send it right over to that computer it's a local call as we say now let's change the story a little bit now we've got a computer over here 10.14 dot 6.7 and this computer over here wants to talk to him now when he takes a look at that address which is going to be 10.14 dot 6.7 you'll see the 10 matches that's great but the next two digits don't match this means it's not on his land luckily any computer that's connected the Internet is part of a network that also has this router thing connected to it and a router is going to have an IP address that which is part of this network and it's usually going to be 10 down 11 not 12 almost always we call the router dot 1 it's just etiquette it's not a law of physics so what will happen is when 44 sees that he can't talk to this guy directly what he does instead is he sends it to 10.11 dot 12.1 so this computer this router acts kind of like a way to the internet in fact that's what we often call this we call it the default gateway so if you want a computer to be on the Internet you're number one gonna have to give it an IP address number two you're gonna have to give it a subnet mask and number three you're gonna have to give it a default gateway the subnet mask is only there to let your computer know if it's a local call or a long-distance call and if it's a long-distance call it sends it to the default gateway where do we type in this IP address and subnet mask and default gateway how do I enter it well you're gonna have to wait for the next episode [Music]

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Keywords: http://www.totalsem.com, Total Seminars, Mike Meyers, CompTIA Certification, Video Training, CompTIA A+, A+, A+ 2019, CompTIA A+ 2019, A+ 220-1001, A+ 220-1002, CompTIA A+ 220-1001, CompTIA A+ 220-1002, A+ 1001, A+ 1002, CompTIA A+ 1001, CompTIA A+1002, IT training, Computers, Computer, Networking, TCP/IP, What is TCP/IP, TCP, IP, Internet, Internet addressing

Id: UNrg38_I6oA

Length: 14min 23sec (863 seconds)

Published: Tue Aug 06 2019