Re: Access-List ( Solution Explanation )

From: Igor M. (imanassypov@rogers.com)
Date: Fri Sep 26 2008 - 11:11:30 ART


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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