Way to Aggregation Subnet

Unanswered Question
Feb 25th, 2008

I have this question.

Say I have the these range of subnets:

And the closest super subnet is

1) I heard from my friend that the lowest number will usually be the super subnet number. Is it true?

2) What is the most fastest way to calculate the super subnet IP?

I have this problem too.
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Jon Marshall Mon, 02/25/2008 - 03:07


1) The supernet will be

2) The way i would work it out is

Subnet mask 22 =

256 - 252 = 4.

So your networks increase by 4 and will take you the next multiple of 4 ie.


Hope this makes sense


Hi Kian

Just to add to what Jon has posted.

Don't get sucked into the "lowest number will be the supernet number" idea.

When you are given IP ranges like your example where they start and finish on a supernet boundry, then yes, the lowest subnet will be the supernet number.

However suppose you were given

In this instance the lowest subnet number does not fall cleanly on a supernet boundry and therefore would NOT be the supernet number.

Personally speaking I would summarise these subnets as follows

There by reducing the number of routes in a routing table from 8 down to 4.


Best Regards,



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