From: Johnny Phan (johnny_d_phan@hotmail.com)
Date: Tue Apr 15 2008 - 13:08:37 ART
After thinking about it a little more, I think I might be mistaken. I was
thinking of the "classic" sense of the word class C. If we go by the
definition below. Then I think Scott is correct.
A Class C address begins with binary 110. Therefore, the lowest number that
can be represented is 11000000, decimal 192. The highest number that can be
represented is 11011111, decimal 223. If an address contains a number in the
range of 192 to 223 in the first octet, it is a Class C address.
----- Original Message -----
From: "Johnny Phan" <johnny_d_phan@hotmail.com>
To: "Scott Morris" <smorris@ipexpert.com>; "'Tarun'" <tarun.ccie@gmail.com>;
"'Athaide, Dwayne'" <DAthaide@eprod.com>
Cc: "'groupstudy'" <ccielab@groupstudy.com>
Sent: Tuesday, April 15, 2008 8:41 AM
Subject: Re: Another Prefix list question
> The correct answer is 192.0.0.0/3 ge 24 le 24 because:
>
> 1) You ONLY want to match the networks between 192-223.
> 2) You ONLY want to match the subnet mask of /24, no more, no less. Try
> it out.
>
> ----- Original Message -----
> From: "Scott Morris" <smorris@ipexpert.com>
> To: "'Tarun'" <tarun.ccie@gmail.com>; "'Athaide, Dwayne'"
> <DAthaide@eprod.com>
> Cc: "'groupstudy'" <ccielab@groupstudy.com>
> Sent: Monday, April 14, 2008 10:53 PM
> Subject: RE: Another Prefix list question
>
>
>> "ge 24" will permit subnetted Class C addresses as well, won't it? :)
>>
>> On the other hand, the "le 32" will also permit SUPERnetted addresses in
>> that range. Just depends on what you are looking for.
>>
>> HTH,
>>
>>
>> Scott Morris, CCIE4 (R&S/ISP-Dial/Security/Service Provider) #4713,
>> JNCIE-M
>> #153, JNCIS-ER, CISSP, et al.
>> CCSI/JNCI-M/JNCI-ER
>> VP - Technical Training - IPexpert, Inc.
>> IPexpert Sr. Technical Instructor
>>
>> smorris@ipexpert.com
>>
>>
>>
>> Telephone: +1.810.326.1444
>> Fax: +1.810.454.0130
>> http://www.ipexpert.com
>>
>>
>>
>>
>>
>> -----Original Message-----
>> From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On Behalf Of
>> Tarun
>> Sent: Tuesday, April 15, 2008 1:40 AM
>> To: Athaide, Dwayne
>> Cc: groupstudy
>> Subject: Re: Another Prefix list question
>>
>> That prefix 192.0.0.0/3 ge 24 means the following.
>>
>> 1) It will match only the first 3 bits of the IP '192.0.0.0' which means
>> any
>> class C address because class C addresses are characterized by a '110' in
>> the beginning of there 1st octet.
>>
>> 2) The 'ge 24' part means that the subnets mask of the class C address
>> just
>> matches has to be either equal to or greater than 24, i.e it will not
>> match
>> 192.168.2.3/16 for example.
>>
>> If you want to permit all "Class C networks" then the prefix list ideally
>> should be
>>
>> ip prefix CLASS_C_NETWORKS permit/deny 192.0.0.0/3 le 32 - this would
>> include all subnetted class C addresses as well.
>>
>> This is a good link on prefix lists:
>> http://ccienotes.blogspot.com/2007/08/ip-prefix-list.html
>>
>> On 4/15/08, Athaide, Dwayne <DAthaide@eprod.com> wrote:
>>
>>> Please check
>>>
>>> If I want to permit only Class C networks
>>>
>>>
>>>
>>> Is this correct?
>>>
>>>
>>>
>>> 192.0.0.0/3 ge 24
>>>
>>>
>>>
>>> Thanks
>>>
>>>
>>> Pass the CCIE in six weeks, Guaranteed!
>>> http://www.certscience.com/CCIE
>>> ______________________________________________________________________
>>> _ Subscription information may be found at:
>>> http://www.groupstudy.com/list/CCIELab.html
>>
>>
>> Pass the CCIE in six weeks, Guaranteed!
>> http://www.certscience.com/CCIE
>> _______________________________________________________________________
>> Subscription information may be found at:
>> http://www.groupstudy.com/list/CCIELab.html
>>
>>
>> Pass the CCIE in six weeks, Guaranteed!
>> http://www.certscience.com/CCIE
>> _______________________________________________________________________
>> Subscription information may be found at:
>> http://www.groupstudy.com/list/CCIELab.html
>
>
> Pass the CCIE in six weeks, Guaranteed!
> http://www.certscience.com/CCIE
> _______________________________________________________________________
> Subscription information may be found at:
> http://www.groupstudy.com/list/CCIELab.html
Pass the CCIE in six weeks, Guaranteed!
http://www.certscience.com/CCIE
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