From: EbonyGuru@xxxxxxx
Date: Thu Aug 15 2002 - 20:29:21 GMT-3
Hey Brian,
Surely you know it is dangerous to play mental games with someone that has
been sucked into the mental vortex thatis called 2 days before your lab.
So, thanks for your help but you must finish what you started.
I believe what you meant to type was the following:
Ip prefix-list CLASS_A permit 0.0.0.0/0 ge 0 le 8
and not:
Ip prefix-list CLASS_A permit 0.0.0.0/1 ge 8 le 8 --- please comment on my
correction.
You have been a great help so far so now please do one of two things, finish
all the classes or refer me to a reliable reference.
So you dont think I am lazy, this is my revised idea of class B filter:
ip prefix-list CLASS_B permit 128.0.0.0/8 ge 8 le 16 ....and so on.
Class C:
ip prefix-list CLASS_B permit 192.0.0.0/16 ge 16 le 24
correct, or way off?
Now bro, end this and quit playing---- :-)
TIA,
E'Guru
In a message dated 15/08/2002 14:39:06 GMT Daylight Time,
brian@cyscoexpert.com writes:
> Subj:RE: IP PREFIX-LIST HELP!
>
>
> Unfortunately no one has gotten it right in this thread yet. If
> you write out the classes in binary, you can see that all class A
> addresses start with a 0 (most significant bit), all class B with 10,
> class C, 110, class D 1110, class E 1111. It's the first 4 most
> significant bits that determine the class of an address.
>
> To match on classful networks, we not only have to match on the
> prefix, but also the prefix-length. Therefore, to accept only classful
> networks, all class A's would have to have a mask of 8, B 16, C 24, etc.
> This can be accomplished with either a prefix-list or an extended
> access-list. Suppose we are matching class A addresses. The first bit
> must be 0, and the mask must be 8.
>
> Ip prefix-list CLASS_A permit 0.0.0.0/1 ge 8 le 8
> access-list 100 permit 0.0.0.0 127.0.0.0 host 255.0.0.0
>
> The prefix-list syntax reads:
>
> Check against the first bit of 0.0.0.0
> The mask is greater than or equal to 8
> The mask is also less than or equal to 8 (exactly 8)
>
> Access-list syntax reads basically the same.
>
> Check the first bit, it must be 0
> The mask is exactly 8
>
> I don't want to spoil all the fun, so let's see if you guys can come up
> with the syntax for class B and class C.
>
> HTH
>
> Brian McGahan, CCIE #8593
> Director of Design and Implementation
> brian@cyscoexpert.com
>
> CyscoExpert Corporation
> Internetwork Consulting & Training
> http://www.cyscoexpert.com
> Voice: 847.674.3392
> Fax: 847.674.2625
>
>
> -----Original Message-----
> From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On Behalf Of
> Chaim Gev
> Sent: Thursday, August 15, 2002 7:51 AM
> To: ciscojunkie@teamhealth.com; EbonyGuru@aol.com;
> ccielab@groupstudy.com
> Subject: Re: IP PREFIX-LIST HELP!
>
> and what about subnets of the callas B networks?
>
>
> >From: "CiscoJunkie" <ciscojunkie@teamhealth.com>
> >Reply-To: "CiscoJunkie" <ciscojunkie@teamhealth.com>
> >To: <EbonyGuru@aol.com>, <ccielab@groupstudy.com>
> >Subject: Re: IP PREFIX-LIST HELP!
> >Date: Thu, 15 Aug 2002 07:59:47 -0400
> >
> >I hate to sound TOO logical, but if you are asked to "filter all class
> B
> >nets" (allow in our deny them in??), would it not simply just be:
> >
> >"ip refix-list zib seq 10 (permit or deny) 0.0.0.0/16"
> >
> >----- Original Message -----
> >From: <EbonyGuru@aol.com>
> >To: <ccielab@groupstudy.com>
> >Sent: Thursday, August 15, 2002 4:57 AM
> >Subject: IP PREFIX-LIST HELP!
> >
> >
> > > Hey Guys,
> > >
> > > Can someone please help me check if this is correct:
> > >
> > >
> > > To filter all class B nets:
> > >
> > > ip prefix-lis zib seq 10 permit 0.0.0.0/0 ge 16 le 24
> > >
> > > Please also tell me where to find a reference with configuration
> >examples.
> > >
> > > TIA.
> > >
> > > E'Guru
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