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supernetting question

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18 years 1 month ago #17378 by gwydion
hi, I need some help with a problem involving supernetting. If I have 2 companies and one of them has 10 departments and a class C address 195.78.63.0 and the other one has 10 contigous class C addresses starting from 195.78.64.0, how do I create a supernetting chemem for these 2 companies? I am confused because I am nost sure if the 3rd octed of the starting address has to be divisible by 2 or by 19 in this case. And what role do the 10 departments of the 1st company play for the supernetting scheme? Thank you.
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18 years 1 month ago #17405 by Dove
Replied by Dove on topic Re: supernetting question
Hi gwydion,
you havnt mention how many systems will be in each department. ok as for 10 department you can use the following supernatting.


255.255.255.240

it gives 256-240=16-2=14 subnets each subnets having 14 host IP address....

so the 1st subnet IPs are 195.78.63.0 -195.78.63.15
2nd subnet IPs : 195.78.63.16 - 195.678.63.31
3rd Subnet IPs : 195.78.63.32 - 195.78.63.47 etc...

like this you may create the suprenat for other IPs too..


Hope it will help you


Dove
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18 years 1 month ago #17453 by zenzippy
Replied by zenzippy on topic Re: supernetting question
Hi gwydion,

company A
the one with 10 departments wil have a summary address of
195.78.63.0/24

Company B
you say they have 10 contiguous class c address 195.78.64.0 to 195.78.74.0

this can be summarized as 195.78.64.0/20 this will be seen by company A's router as one big supernet of 195.78.64.0/20

the mask of /20 will summarize upto a block of 16, so 195.78.64.0 to 195.78.79.0


well thats how I understand it.
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18 years 1 month ago #17454 by zenzippy
Replied by zenzippy on topic Re: supernetting question
oops, just realized these are not private address so maybe a block size of 8 would be a better answer.
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18 years 1 month ago #17476 by Smurf
Replied by Smurf on topic Re: supernetting question

Hi gwydion,

company A
the one with 10 departments wil have a summary address of
195.78.63.0/24

Company B
you say they have 10 contiguous class c address 195.78.64.0 to 195.78.74.0

this can be summarized as 195.78.64.0/20 this will be seen by company A's router as one big supernet of 195.78.64.0/20

the mask of /20 will summarize upto a block of 16, so 195.78.64.0 to 195.78.79.0


well thats how I understand it.


Thanks for that answer, i was struggling to see how you could fit just upto 195.8.74.0 range and thought you would have to go beyond it. Glad i was on the same wave length.

Wayne Murphy
Firewall.cx Team Member
www.firewall.cx

Now working for a Security Company called Sec-1 Ltd in the UK, for any
Penetration Testing work visit www.sec-1.com or PM me for details.
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18 years 1 month ago #17567 by Dove
Replied by Dove on topic Re: supernetting question
Hi Zenzippy,
How you applied block size 8 for your requirement. you said you need 10 IPs for each dept know then how come.

The possiblity is either you can use the block size 16 and above only.

can you tell me how you subnetted.


Dove
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