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Question Regarding Summarization

rai_praveen
Level 1
Level 1

A router has a summary route to network 192.168.0.0/22 installed in its routing table. What range of networks are summarized by this route?

pls tell me this in concise why i did my calculation but i have not figure out the network this summarize route include thats why i ask here so pls show me the answer with calculation so i will learn the method

2 Accepted Solutions

Accepted Solutions

Ziga M
Level 1
Level 1

192.168.0.0/22 has subnet mask 255.255.252.0 and it matches IPs from 192.168.0.0 to 192.168.3.255

View solution in original post

OK so you want to knwo what subnets will be part of summerized block of
192.168.0.0/22. It could be many /25 many /23 or anything from /32 to /22.

Lets assume you want to know which are the block of /24 are part of this summerized
block.

Considering the above query i had given you method.

Ok let me try in some other way /22 will have subnet as 255.255.252.0 and reference subnet is /24 which is having
subnet mask as 255.255.255.0

so If you consider third octate which is 252 in /22 and 255 in /24.

In short when you substract 24-22 which is 2. So you have 2 bits to work upon

it could be

00.....192.168.0.0/24
01.....192.168.1.0/24
10.....192.168.2.0/24
11.....192.168.3.0/24

Here you have moved from 0 (192.168.0.0/22) to 0,1,2,3 (above mentioned /24's)

Let me know if this was your question

Regards
Mahesh

View solution in original post

14 Replies 14

Ziga M
Level 1
Level 1

192.168.0.0/22 has subnet mask 255.255.252.0 and it matches IPs from 192.168.0.0 to 192.168.3.255

brother thanks for reply

can you tell me the calculation you done  to find these address because as per my knowledge /22 has a block size of 4 so if we start as per my calculation below

192.168.0.0

192.168.4.0

192.168.8.0

this output will come but you told that

192.168.0.0 - 192.168.3.255

how pls clear it

Hmm.. after a while, you can calculate direct from the head, so I can't provide you with a formula. Check this:

http://www.subnet-calculator.com/

I went from 24 down, so /24 is 192.168.0.0- 0.255

/23 is 0.0 to 1.255

/22 is 0.0 to 3.255

/21 is 0.0 to 7.255

15.255

31.255

63.255

and so on....

brother sorry i didn't get can you be more precise i don't want subnet calculator to do i want to do manually

pls be more concise about below method.

I went from 24 down, so /24 is 192.168.0.0- 0.255
/23 is 0.0 to 1.255
/22 is 0.0 to 3.255
/21 is 0.0 to 7.255

brother then what address this summerize address contain 172.16.0.0/12.

pls brother reply me in little bit describe way.

pls reply i need to know about summeriztion

i just want to know how you find block size from this summerize address 172.16.0.0/12.

because for /12 block size would be 16 so network increment start like this

172.16.0.0

172.16.16.0

172.16.32.0

am i right  pls reply with answer so i learn the concept

Hello praveen,

Below is the method

If you want to divide /22 into /23 then there is difference of 23-22=1
so 2 to the power 1 which is equal to 2

so there are two possible subnet 192.168.0.0/23 and 192.168.2.0/23

Now say you want to divide /22 into /24 then difference is 24-22=2


so 2to the power 2 equal 4 so possible /24 subnet will be 4

192.168.0.0/24
192.168.1.0/24
192.168.2.0/24
192.168.3.0/24

Hope this helps

Regards

Mahesh

dear mahesh

brother why you divide /22 by /23 then /24 only why not from /25 also second think what is the block size in case of /24 as per my knowledge 4 then network increment start from 0,4,8 so on but for /24 you tell 0,1,2,3 how brother i didn't get so pls pls more precise

OK so you want to knwo what subnets will be part of summerized block of
192.168.0.0/22. It could be many /25 many /23 or anything from /32 to /22.

Lets assume you want to know which are the block of /24 are part of this summerized
block.

Considering the above query i had given you method.

Ok let me try in some other way /22 will have subnet as 255.255.252.0 and reference subnet is /24 which is having
subnet mask as 255.255.255.0

so If you consider third octate which is 252 in /22 and 255 in /24.

In short when you substract 24-22 which is 2. So you have 2 bits to work upon

it could be

00.....192.168.0.0/24
01.....192.168.1.0/24
10.....192.168.2.0/24
11.....192.168.3.0/24

Here you have moved from 0 (192.168.0.0/22) to 0,1,2,3 (above mentioned /24's)

Let me know if this was your question

Regards
Mahesh

thanks brother

now i am gettingthe concept little bit can we have some more example related to my question just forget my question and you pick some address and describe so i get the concept fully

pls reply brother you method of telling thing is very good some more examples and i will get the concept fully

let take this summarize address 172.16.0.0/12

now pls tell me the subnet this summerize address contain

Hello praveen,

Sorry for the late reply . actually I was on dinner.

Well If you want to divide /12 into /24 then it is dificult to show the method here because it has difference of 12 (>octate size of 8)
so there will be two octate for which we consider.

Lets do it like dividing /12 into /15. so we will have 15-12=3 bits for subnetting and  the total subnets will be 2^3=8

/12: 255.240.0.0
/15: 255.254.0.0

Now to calculate subnet you just need to substract 254 from 256 (256-254=2) hence the subnet will be in increment of 2

like

172.16.0.0/15172.16.0.0/14172.16.0.0/13172.16.0.0/12
172.18.0.0/15
172.20.0.0/15172.20.0.0/14
172.22.0.0/15
172.24.0.0/15172.24.0.0/14172.24.0.0/13
172.26.0.0/15
172.28.0.0/15172.28.0.0/14
172.30.0.0/15

I think you are asking me about summerization and I am replying about subnetting, but anyway both are connected as a concept. In short your /12 an contain above eight /15 or it could contain four /14 or two /13. Same way you can expand it upto /24

Regards

Mahesh

hi Mahesh

   brother thanks for reply.wait i just tell you what i want two know suppose 192.168.0.0 /22 is a summarize route ok

now i just want to know what subnet this summarize route contain now you told me the addresss are

192.168.0.0

192.168.1.0

192.168.2.0

192.168.3.0

ok now pls tell me how you find the increment number from this summarize route 192.168.0.0. /22 to get this 4 address

192.168.0.0

192.168.1.0

192.168.2.0

192.168.3.0

hope now you understand what i want to know

   pls Brother reply me with easy details so i get the concept and i am able to interpret the summerize route and know what subnet this sumerize route contain in it

Hello praveen,

192.168.0.0/22  255.255.252.0

For above address you want to know what sort of /24 address it may contain.Just follow below two steps

> First decide how many subnets of /24 would be there in /22


  /22 has a mask 255.255.252.0 and /24 has mask 255.255.255.0 so substract
  22 from 25 which yield 2. hence the no. of subnets it will contain is 2^2=4

> Next you will decide what are those subnets


  well all you need is to find the difference (substract 255 from 256 , 256-255=1

  so   there will be difference of 1) hence you every subnets will be in increment of 1

  like

  192.168.0.0/24,

  192.168.1.0/24,

  192.168.2.0/24

192.168.3.0/24.

In short you need   to follow these two steps.

Lets do same for deciding how many /25 will be there in /22 address

Step-1> 25-22=3 so 2^3 will be 8, It contain eight /25 subnets
Step-2> /25 subnet-mask is 255.255.255.128. Result of step-2 is  256-128=128, so every subnet will be
  in increment of 128.

  like

192.168.0.128
192.168.1.0
192.168.1.128
192.168.2.0
192.168.2.128
192.168.3.0
192.168.3.128
192.168.0.128

Hope this time it is clear

Regards

mahesh
 
 

thanks thanks thanks brother finally i got the concept thanks for such wonder ful explanation

may i know you gmail email address so if got any problem i will contact you on chat if you don't mine pls share i won't disturb you

But thanks again for you explaination

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