From: Elias Chari (elias.chari@gmail.com)
Date: Sun Jun 04 2006 - 14:57:55 ART
Hi again,
I think I cracked it, please test it and tell me what you think. This is all
done with the MS calculator in decimal, so you don't have to worry about
writing the numbers in binary.
Example-1
========
54.1.1.0
150.1.6.0
AND operation gives a network of
22.1.0.0
Do OR of the networks and end up with
182.1.7.0
subtract the network you found earlier and you get the wildcard
160.0.7.0
Therefore ACL is network 22.1.0.0, wildcard 160.0.7.0
Example 2
========
54.1.1.0
150.1.6.0
35.22.48.0
AND gives 2.0.0.0
OR gives 183.23.55.0
Suntract and you get
181.23.55.0
Therefore ACL is network 2.0.0.0 wildcard 181.23.55.0
On 6/4/06, elias.chari@gmail.com <elias.chari@gmail.com> wrote:
>
> Hi Group,
>
> I guess you have all come across a requirement to match multiple networks
> with a one line ACL.
>
> I understand the theory i.e AND operation to get the network part and X-OR
> for the wildcard. Now writting out all the networks in binary and doing the
> operations is time consuming and quite easy to make a mistake when under
> pressure.
>
> I have tried to work it out using the AND and X-OR functions on the MS
> calculator and whilst it woks ok for the AND operation for multiple
> networks, it fails on the X-OR function as it does a comparison of two
> networks at at time.
>
> Has anybody worked out how to get the calculator to compare multiple
> numbers using the X-OR function?
>
> BTW it works for AND when using the networks in decimal format...-)
>
> If we crack this, it could potentially save us quite a bit of time.
>
> Regards,
> Elias
> PS - The equation for an X-OR gate (for those not familiar with it and may
> be interested) is:
> __
> Y = (A+B)(AB)
>
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