From: Frank (ocsic@web.de)
Date: Wed Sep 13 2006 - 05:01:32 ART
Zikopoulos Aristomenis schrieb:
Hi Aris,
coud you explain a bit more what you mean with "many mistakes"?
Do you mean on the IE webpage or on my calculation regarding to
the IE link?
Frank
> Hello ,
> There are many mistakes.
> Check the forum. http://forum.internetworkexpert.com/
> Regards,
> Aris
>
> -----Original Message-----
> From: nobody@groupstudy.com on behalf of Frank
> Sent: Wed 9/13/2006 10:06 AM
> To: Cisco certification
> Subject: access-list mask/wildcardmask calculation
>
> Hi,
>
> here is a source from IE for calculating ip access-list mask and
> wildcardmasks.
>
> http://www.internetworkexpert.com/resources/01700370.htm
>
> I have a question regarding this .
>
> I'm currently comparing my results and the ways described there and
> calculations
> are different from what i would setup the "normal" way.
>
> Do you understand what i mean? Here is an example:
>
> Two addresses that should be covered by an access-list.
>
> 192.168.32.5
> 192.168.48.99
>
> The IE page says:
>
> 11000000 => 192
> 11000000 => 192
> bbbbbb- AND
> 11000000 => 192
>
> 10101000 => 168
> 10101000 => 168
> bbbbbb AND
> 10101000 => 168
> 00100000 => 32
> 00110000 => 48
> bbbbbb AND
> 00100000 => 32
>
> 00000101 => 5
> 01100011 => 99
> bbbbb- AND
> 00000001 => 1
>
> Resulting mask 192.168.32.1
>
> Wildcardmask:
>
> 11000000 => 192
> 11000000 => 192
> bbbbbbXOR
> 0000000 => 0
>
> 10101000 => 168
> 10101000 => 168
> bbbbbbXOR
> 00000000 => 168
>
> 00100000 => 32
> 00110000 => 48
> bbbbbbXOR
> 00010000 => 16
>
> 00000101 => 5
> 01100011 => 99
> bbbbb-XOR
> 01100110 => 102
>
> Resulting wildcardmask: 0.0.16.102
> So for the IP addresses
> 192.168.32.5
> 192.168.48.99
>
>
> The mask for a matching access-list is 192.168.32.1 and the wildcardmask
> is 0.0.16.102
> ip access-list 1 permit 192.168.32.1 0.0.16.102
>
> Is this the most optimal mask calculation?
>
> But i would set up:
>
> ip access-list 1 permit 192.168.32.0 0.0.31.255
>
> To match the 192.168.32.0 subnet to 192.168.63.255 where i cover both ip
> addresses.
> What is the difference. Is the other result more opimal in just covering
> these two addresses?
>
>
> Frank
>
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This archive was generated by hypermail 2.1.4 : Sun Oct 01 2006 - 16:55:40 ART