Time
15 hours 34 minutes
Difficulty
Intermediate
CEU/CPE
20

Video Description

Classless IP Addressing (part 1) Now that we've discussed Classful IP Addressing, we diagram and explain Classless IP addressing and examine what the differences are between the two and why they exist. You'll learn how to sub divide a class B IP address into smaller "sub" address or subnet mask when more addresses within the same IP address are needed and how those "sub" address are determined.

Video Transcription

00:04
Now we move away from the world of class ful I p address ing to class less addressing.
00:09
Why?
00:11
Well, because, for example,
00:14
if you pick a classy address 210 10 10 So 210 10 10
00:22
slash 24. Since this is a classy address or the mass being 2552552550 or represented as last 24
00:32
the network addresses 210 dot Tenn 210.0.0. The range of addresses that can be derived from this is 0.12 dot to 54
00:45
dot to 55 being a broadcast,
00:51
so you can get 254 addresses using a classy address base.
00:57
If you
00:58
pick a Class B address space,
01:00
you get more addresses than 2 54 and a class C
01:04
class address range. You get a huge number
01:07
16777214 I believe
01:11
what if your company
01:12
I asked you to purchase
01:15
I p addresses for them
01:17
and they wanted 30 addresses?
01:19
Well, if we were still using Class A, B and C, you could come back with a classy range,
01:26
but you would have still bought 254 addresses. So because because you would have to buy the whole class the whole range.
01:34
So if somebody asked you to spend,
01:38
let's say these addresses cost $1000 a month. They ask you to spend $30,000 you spend $254,000. You're in trouble.
01:49
So class full I p address ING won't work if we need address is less than 254.
01:56
So let's pretend our company needs 30 addresses.
02:00
How do we do that? Let's start with the night. Be 1 51 0 on 45.0. Now this technically is a Class B addressed
02:12
because it falls within the range off between 1 28th
02:16
and 1 91
02:17
So this should be a slash 16 or 25525500
02:23
What happens if I give it a slash 27 mask? Well, the first thing I want to find out is what would the mass look like in dot and decimal?
02:31
This is the cider notation, the slash format. What would the Mass look like? What would it be to 55255255 something right?
02:40
Well,
02:43
24 bits. I definitely turned out
02:46
in the 1st 3 out,
02:47
so the 1st 3 objects would simply be 255255 and 255 So the first act it is all ones, which gives me eight bits. Second octane is all ones, which gives me a total of 16 bits. Eight plus eight.
03:01
And then the third op ed is also all turned on, which gives me plus 8 24 bits.
03:08
Three extra bits are turned on
03:10
in the last doctor of the fourth Doctor.
03:14
Let's find out what that does to 345
03:20
six,
03:22
7812
03:24
48 16 32 64 1 28
03:32
So three bits turned on here
03:37
and the rest are off.
03:40
If I add up 1 28 64 32
03:46
I get
03:47
2 24
03:50
So the mask and dotted decimal would end up being 255255255 to 24.
03:57
How many total hosts can I have in this network?
04:00
Let's find out.
04:01
You start at 1 50
04:04
101
04:06
45.0. This is
04:12
my network address. I look at the value off the last bit turned on in the subnet mask. Hence I put a square around it.
04:20
The value of the last bit turned on in the subnet mask is 32.
04:26
Remember this rule? This gives me my block size. What do I mean by block size? See in a second.
04:32
So always remember when solving questions with class less I P's always turned the sub net mask into binary. And you don't need to turn the whole mascot by angry because the first octet, second doctored and third doctor are all ones.
04:47
The four talk that the relevant that you're working in, you can turn it into binary
04:53
and look at the value off the last bit turned on.
04:57
So 27 bits turned on or slash 27 simply means 8883
05:03
And I only drew out the last octet with three bits on because the 1st 3 AQ taps are all ones anyways,
05:11
So when you look at the value of the last bit turned on, this gives me my block
05:18
size.
05:20
That simply means that if this is my first street or my first network, my next street starts at 1 50
05:30
101.45. 32.
05:36
I just added 32 to 0.
05:41
My next street would start at
05:44
1 50
05:46
0.101 dot 45.64
05:55
and I would keep adding 32. How did I get 64? I added 32 again and I got 64. If I had 32 again, if I had space,
06:02
the next network or the next street would start at 96 so on and so forth. All the way till 255
06:11
So, my first valid host for this first street, my first valid house address is dot Won. My last possible address on this street would be dot
06:21
31. However, remember the rule. The last possible address on any network
06:29
is your broadcast. So my valid range would be between one and
06:36
30. So 1 50.121 dot 45.1 would be my first valid address.
06:43
1 51 21.45 30 would be my last valid address.
06:48
Did I get 30 addresses? Yes. Did we need 30? Yes. What I'm looking for from you if I asked you to go by 30 addresses is
06:58
an I P address with a slash 27 mask or a 255255255 to 24 mask
07:04
again. The next street over.
07:06
My first valid would be 33. My last possible address would be 330.63 which is my broadcast. My last valid address, which is assign Herbal would be 62 my Rangers again total of 30 addresses. This would be my valid ridge.
07:25
Now, could I use
07:26
that? Two to the power and minus two formula here. Of course I could. How many host bits do I have? 12345
07:35
True to the power five minus two to the power five is 32 minus two equals
07:45
30.

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