Create a Subnet

MicroCourse
Time
55 minutes
Difficulty
Beginner
CEU/CPE
3

Video Description

IP Addresses in Relation to the OSI Model This lesson focuses on how IP addresses fit into the OSI Model. IP addresses are logically mapped addresses that map to a physical address. IP addresses aren't mapped to a computer and can be mapped to any MAC we want, they can change and move. They are not hard encoded and are set statically. An IP address is a 32-bit binary address and is divided into four sections called octets, this is because each section has eight numbers. Participants learn how to calculate octets using a specific numerical sequence, starting with one and incrementing our way up by powers of 2.

Video Transcription

00:04
Hi and welcome to cyber dot i t. My name's Anthony and I'm your local subject matter expert here for Network Plus And today we're gonna be talking about the properties of I P addresses. So let's take a look at I p addresses. Now we've talked about how I ke addresses fit into our layer three of roos I model in our network layer,
00:21
but what our I p addresses what do what do they dio
00:25
and how do we compose them and what do they look like? Well, I p addresses our our logically mapped addresses that map to a physical address. So when we say that they're logically assigned addresses, what we mean is that our I p address weaken set for any computer.
00:42
If he addresses aren't hard encoded to a computer so we can map them
00:46
to any particular physical address, we can map them to any Mac address that we want. Thio on I P address can point to one computer one day in the very next day point to a completely different computer. So our I P addresses are logical addresses that can change. Our computers can have multiple i p addresses throughout the course of a day just because we moved between different networks.
01:06
So we want to understand that these I p addresses. They're not hard encoded.
01:10
These I p addresses are provided to our computer by the network were on or are set statically by us. So we need to understand what these different I p addresses are and how we get them.
01:21
So what's the format of an I P address? Well, an I P address is what's known as a 32 bit by an area dress. When you see an I P address on your computer, you'll see something such as 1 92.1 68.1 dot one.
01:41
That's an I P address.
01:42
Our computer doesn't know how to understand that just by reading the numbers 1 92.1 68.1 dot one.
01:51
At its base level, computers on lee understand electrical signals. Computers can on lee stand, understand, on or off
02:00
a one or a zero in binary language. Binary language is the language of computers, is the language of processors and is the base level of how our computers talk. Binary lets our computers know if there is a signal that's on, or there's a signal that's off
02:19
and then on in. Buying area is represented by a one
02:23
and then off in binary is represented by zero. So all of our numbers, all of our characters, all of our programs are all at their base level. Just a bunch of binary, a bunch of binary code that has been written out. So our I P address are 1 92.1 68.1 dot one
02:42
is also buyin ery code. It's a
02:45
string of numbers that's made up by using this buyin Eri
02:50
So
02:52
I p Version four addresses are 32 bit by in area dresses, which means that we have 32 ones or zeroes in our dress.
03:00
It We counted these out earlier, and we have 32 here,
03:05
so 32 bit addresses. We have 32 ones and zeros.
03:08
These addresses are divided into four sections known as octet. It's and the reason they're called octet CE is because in each section
03:17
they have
03:19
eight numbers.
03:21
So how do we go from having an address that looks like this 32 ones or zeroes to an address that looks like this. An actual numerical i p address. Well,
03:32
these sections increments by powers of two.
03:38
So let's take a second there. What me might mean by that?
03:40
Well,
03:43
if we start at the very right hand number of an octet, and we remember because we're breaking it up into four, we're starting at the very right hand side of an octet, a set of eight separated by a period.
03:55
This very first number in an octet
04:00
represents
04:01
a value a of one or value of zero.
04:05
I think of it almost like an abacus, with several different with several different
04:12
low are with several different rods, but only one bead on each rod.
04:16
If our
04:18
if our number in our zero or one's place is a zero is an off electrical signal, then it stands for zero.
04:28
If it's a one, then it's an on.
04:31
So we move over to our next place. We increments by a power of two,
04:36
and our section now stands for a two or a zero.
04:43
So if our next number is, if our next number in our octet sequence is on, if it's a one, then that means that we add two if it's zero than it's off, we don't add to.
04:57
And that continues on. Uh, we have won. We have won one's place two's place for
05:03
eight,
05:04
16 32
05:08
64 1 28
05:11
when we add up all of these together, if we have a string of buyin Eri in our octet, if we have an entire octet, that is all on. If every single place is a one, then our max number is 255.
05:28
If all of our numbers in an octet or a zero than our number is zero, that's our lowest number that we can have.
05:34
Now when you think of zero, when you think of numbers in in math, you think of annul value. When you think of zero, you think of a nothing
05:44
in our I P addresses, though an address with a zero is a completely valid number, is a completely valid address. Now, not all zeros, but if, for example, are addressed here was 1 92.1 68 not 1.0. That's a valid address,
06:00
so we need to make sure that we or it can be a valid address, depending on our sub nets,
06:06
but so we need to make sure that we understand that if we're counting, if we're counting sequences of address, if we're counting how many numbers are possible in a certain octet?
06:19
Technically, we don't have just 255 available
06:25
because, ah, string of zeros also counts as a digit. We have 256 values available
06:33
250 0 to 255 because zero counts is a value. So we have 256 values available. But the highest number that we can have is 255. Understanding that we have 256 total values available will come
06:51
will come into play later when we're talking about some more
06:56
complicated issues known a sub netting. But just remember that we have 256 total values available, but 255 is the highest number that we can put in. So
07:06
we have our buying Mary here.
07:10
This is what our computer sees. This is our This is our computer language,
07:15
and we need to translate this buyin eri in tow a number so that we can see well, let's start and let's just dissect this entire string of binary. Remember, our I P V four addresses are 32 bit binary dress is divided into four octet. It's four sets of
07:32
eight numbers. Device separated by period
07:35
and we're incrementally from. We'll start with one and then increment by powers of two.
07:44
So
07:45
let's start with our
07:46
left. Most address here are left most octet here.
07:51
Now, if we take this octet and we'll fill it into our chart here, we already explained how are zeros? Place increments. So we started. We fill out our chart. Here we have a one, so just fill in 10
08:05
one
08:07
one
08:09
zero
08:09
zero
08:11
zero
08:13
zero.
08:13
So we have a will start from our highest number and we'll go down.
08:20
We haven't. We have a one. We have an on switch in our 128 place.
08:26
So our number right now is 128.
08:30
We have nothing in our 64 place we have in on in our 32 place. So now add 32 because it's on to our 128.
08:39
Now we add 16 because we have on on our sixteen's place
08:46
and then the rest are zeros. So plus zero plus zero plus zero plus zero. But we don't have to show those. So we have 128
08:54
plus 32 plus 16
08:58
and that will leave us with 128
09:03
128 plus 32
09:05
add to carry the one, we're gonna have 160
09:09
and then we add our 16 and we're gonna have 176.
09:16
So our first number here
09:18
is going to be 176
09:22
Now we have a first number.
09:24
As you can see, this takes a long time, which is why we don't do this all by hand. We do have calculators available for this, but we need to understand at this point in our discussion, we need to understand how this is done.
09:37
So our first places 1 26 miles pick up the pace a little bit. Now our next place is going to be all ones. Now we already know that our highest value when we have all ones is to 55. But let's show why. That's why that is why it iss
09:52
So we have one on on and on and on and on and on and on and on on. We have no office. We have no zeroes in this set in this octet.
10:03
So we have won 28
10:05
1 28 plus 64 1 28 Plus, our 64 is going to give us 192.
10:13
So 1 28 plus 64 is
10:16
1 92
10:20
and then we add that to our 32
10:22
and our 1 92 plus, our 32 is going to give us 2 24 are 2 24 plus our 16 is going to give us 2 40
10:35
all right
10:37
to 24 plus 16
10:41
equals 2 40
10:43
And now our 2 40 plus eight is to 48.
10:46
2 48 plus four is going to be 2 52
10:50
2 52 plus two is going to be 2 54 and 2 54 plus one is going to be 2 55 So that's why our highest number is 2 55 Because when all of our places in our octet are on
11:05
our numbers to 55.
11:07
So let's take a look at our math for this number our math for this octet.
11:13
So we have our place. Here are 1 28
11:16
plus 64 is going to give us our 1 92
11:22
now 1 92 plus 32 is going to give us our 2 24
11:30
And then finally to 24 plus 16
11:33
is going to give us
11:35
two.
11:37
40.
11:37
So our 11110000 the rest of us zero. So we don't add anything. We now end up with 2 40
11:48
So our I p address we have represented in red
11:52
in a number that is easier for us to understand, is going to be 1 76 to 55.0 dot 2 40 And now we know how we figured that out.
12:03
So now we know howto work forward with a number
12:05
we took Our buyin Eri are 32 bit address and we worked it into a number Are we worked it into a new an I P address.
12:13
So what do we do if we need to go the opposite way? We need to go from
12:20
1 92.1 68.1 dot one into buying Mary this is useful when we're doing submitting. This is useful when we're working with more advanced features of our I P addresses. So let's take a look and figure out how we do that.
12:33
So
12:33
let's keep our chart. This is a very useful chart, by the way, if you're taking an exam or you are in a situation where you need to be doing, you need to do sub netting or you need to do I p address functions that require you to translate it into binary.
12:50
But you can't have an I P address calculator for whatever reason.
12:54
Then it's good to set up this chart first on a on a marker board or on a piece of paper, so that you'll have a template toe work with is very It's very good and very simple chart to set up.
13:07
So we have our address, and now we're gonna work backwards. R I P address is 1 92.1 68.1 dot one.
13:18
So what do we d'oh? We take our 1 92 and we start from the left of our chart again and work to the right and essentially we start subtracting from our 1 92 And if our value is small enough to fit into our 1 92 we put in on in that switch
13:37
because our binary works from left
13:39
are left to right. So that's how we need to start.
13:43
So we have 1 92
13:45
and we start from the left.
13:46
Does our 1 92 is 1 28 smaller than 1 92? Yes.
13:52
So we put on in one in our 1 28 place. But we also subtract that 1 28 from our 1 92
14:01
So we have 1 92
14:03
minus 1 28
14:07
And that's going to leave us with
14:11
64
14:11
now
14:13
the 64 fit into 64? Yes, exactly. So 1 92 minus 1 28 equals 64 64 does fit into 64. So we put in on there
14:24
and then 64 minus 64 equals zero.
14:30
So there's not gonna be any more numbers here that fit into that. So no, nothing fits into zero. So the rest of these are going to be zero.
14:41
So that means our first octet for our 1 92.16 th Not one, not one. Our first octet is going to be 1100
14:50
00
14:52
00
14:54
That's gonna be our first octet. 12345678
15:00
Now our next one are 1 68
15:03
Let's go ahead and clear our chart. Back out. So now let's move on. To our next number are 1 68 now are 1 68
15:11
There's our 1 68 fit into 1 28 Yes. So we put it on in our 1 28 and 1 68 minus 1 28 equals 40.
15:22
Now the 64 fit into 40. No, does not. So we have an off in our 64 place.
15:30
What, about 32 to 30 to fit into 40? Yes, it does.
15:33
So we said we put in on in our 32 we subtract 32 from 40.
15:39
And this is gonna leave us with eight.
15:41
The 16 fit into eight. No.
15:43
Does that fit into eight? Yes, exactly. So we put in on in our eight. Subtract eight from eight, leaving us with zero, and then the rest of our places are going to be zeros.
15:54
So now our next
15:56
octet is going to be
15:58
10101
16:03
000
16:07
Now, last two off tests are fairly easy. We may even be able to do them without even referencing our chart a lot. But we'll reference our chart for one of them.
16:15
Just for demonstration purposes.
16:18
Our next two octet. It's our ones.
16:22
So there's We have a one over here,
16:26
but just so we have to form a habit, we're gonna start from left to right. Even though I think I know, I think we all know where this is going.
16:33
There's 1 28th into one. No,
16:36
the 64 fit into one. No, this 30 to fit into one. Know the 16 fit into one? No. Is eight fit into one? No, just four fit into one? No, just to fit into one. No, there's one fit into one. Thank you. Finally. Yes, it does.
16:51
So one fits into one. So our next octet and the one after that because it's exactly the same are all zero
16:59
00000
17:03
0112345678 And then our last octet is going to be the same. 0000
17:14
000112345678
17:19
So
17:21
that's how we translate from our standard i p address toe binary. And then we showed how earlier how we translated from binary to a standard I p address all with the use of our handy dandy little chart and all with an understanding of how these binary switches work and how we increments.
17:41
We started one and we increment up our way by powers too.

Up Next

Create a Subnet

Learning to subnet fast and accuratey is key to computer networking. Progress beyond the basics of binary and master this fundamental skill in less than an hour.

Instructed By

Instructor Profile Image
Anthony Harris
Systems Analyst and Administrator at SAIC
Instructor