From: marvin greenlee (marvin@ccbootcamp.com)
Date: Tue Dec 07 2004 - 15:50:43 GMT-3
If you want ONLY 24 bit subnets, you need ge 24 le 24. By itself, ge 24
will allow anything with a mask that is 24 bits or longer. By setting the
ge AND le, you are making both a requirement. Ge 24 le 25 would allow
either a 24 bit or a 25 bit mask, for example.
- Marvin Greenlee, CCIE#12237
Network Learning Inc
marvin@ccbootcamp.com
www.ccbootcamp.com (Cisco Training)
-----Original Message-----
From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On Behalf Of
adeolu@sympatico.ca
Sent: Tuesday, December 07, 2004 10:23 AM
To: gladston@br.ibm.com; ccielab@groupstudy.com
Subject: Re: Re: PREFIX LISTS [bcc][faked-from]
Importance: Low
Thanks for clearing that up. Another slight variation....
ip prefix-list test seq 10 permit 192.168.32.0/21 ge 24
The intention is to ensure that only /24 subnets of the supernet are
permitted.
Will the prefix-list work?
>
> From: gladston@br.ibm.com
> Date: 2004/12/06 Mon PM 03:16:20 EST
> To: ccielab@groupstudy.com
> Subject: Re: PREFIX LISTS
>
> Hello,
>
> Hope somebody correct me if I am wrong.
>
> By Halabi definition:
>
> "Supernet is any network that contains fewer bits than a network's natural
mask"
>
> ip prefix-list test17 seq 5 deny 0.0.0.0/1 le 7
> matches 0 to 127, with mask less than 8 (127 loopback and le meaning 7
and less)
>
> ip prefix-list test17 seq 10 deny 128.0.0.0/2 le 15
> matches 128 to 191 with mask less than 16
>
> ip prefix-list test17 seq 15 deny 192.0.0.0/3 le 23
> matches 191 to 223 with mask less than 24
>
> So far, so good. Denies any supernet of all Classfull.
>
> Permit everything else:
>
> ip prefix-list test17 seq 20 permit 0.0.0.0/0 le 32
>
> ===================
> quoted
> Can this also be answered as follows?
> ===================
>
> ip prefix-list test17 seq 5 permit 0.0.0.0/1 ge 8
> matches 1 to 127 with mask greater than 7
> will match classfull and subnets of the range 1 to 127
>
> ip prefix-list test17 seq 10 permit 128.0.0.0/2 ge 16
> matches 128 to 191 with mask greater than 15
>
> ip prefix-list test17 seq 15 permit 192.0.0.0/3 ge 24
> matches 192 to 223 with mask greater than 23
>
> ip prefix-list test17 seq 20 deny 0.0.0.0/0 ge 32
> matches everything else
>
> Yeah, I think you reach your goal both ways.
>
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