From: S Malik (ccie.09@gmail.com)
Date: Sat Sep 27 2008 - 09:36:12 ART
Correction please,
For Network portion it should be ANDed and for WC.Mask it should be XORed.
For AND operation all the bits should be 1 (high) to get o/p of 1 and for
XOR, if all the bits are same (either all bits are 1 or 0) then o/p is 0,
Therefore AND will result in 0000 1000 = 8
XOR will result in 0000 0011= 3
On Sat, Sep 27, 2008 at 8:13 AM, S Malik <ccie.09@gmail.com> wrote:
> For Network portion it should be ANDed and for WC.Mask it should be
> XORed. For AND operation all the bits should be 1 (high) and for XOR, if all
> the bits are same (either all bits are 1 or 0) then o/p is 0,
>
> Therefore AND will result in 0000 1000 = 8
> XOR will result in 0000 0011= 3
>
> On Fri, Sep 26, 2008 at 10:11 AM, Igor M. <imanassypov@rogers.com>wrote:
>
>> 128.128.8.0
>> 128.128.9.0
>> 128.128.10.0
>> 128.128.11.0
>>
>> You have too look for matching and differing octets, in this case octets
>> 1,2
>> and 4 are the same. Also you got to remember that '1' is a dont-care, and
>> '0'
>> is a 'match'
>> Now the differing one - octet 3. Convert each one of them
>> to binary:
>>
>> 0000 1000
>> 0000 1001
>> 0000 1010
>> 0000 1011
>> ---------
>> 0000 1100 (bitwise AND) - this is your host portion of acl
>> 0000 0011 (0 - match, 1 - dont care)
>>
>> ip access-list standard ACL-BB1
>> permit 128.128.12.0 0.0.3.0
>> hth
>>
>> ----------------------
>>
>> I.M., M.Eng. P.Eng.
>>
>> Network Architect
>>
>> CI Investments
>>
>> ----------------------
>>
>> --- On Fri, 9/26/08, Razzaq Shaikh <shaikh.razzaq@gmail.com> wrote:
>> From: Razzaq Shaikh <shaikh.razzaq@gmail.com>
>> Subject: Access-List ( Solution Explanation )
>> To: "Cisco certification" <ccielab@groupstudy.com>
>> Received: Friday, September 26, 2008, 9:50 AM
>>
>> Hello,
>> Please someone can explain the solution
>>
>> queston) Allow only 128.128.8.0 / 128.128.9.0 /128.128.10.0
>> /128.128.11.0routes from BB1
>>
>> answer) ip access-list standard ACL-BB1
>> permit 128.128.8.0 0.0.3.255 ( * what is the formula for
>> this )
>>
>>
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