From: ccie2be (ccie2be@nyc.rr.com)
Date: Fri Nov 05 2004 - 01:01:42 GMT-3
No, those 2 prefix aren't the same.
The 1st prefix list means that the 1st 24 bits must equal to 192.168.0 and
the net mask is 24 bits long.
The 2nd perfix list means that the 1st 24 bits must equal 192.168.0 (same as
before) but the le 32 that follows means the net mask can be from 24 bits
long to 32 bits long.
Don't overlook that le means LESS THAN OR EQUAL.
So, the 1st perfix list means 192.168.0.0 255.255.255.0 ONLY/
The 2nd prefix list means the following matches:
192.168.0.0/24
192.168.0.0/25
192.168.0.0/26
192.168.0.0/27
192.168.0.0/28
192.168.0.0/29
192.168.0.0/30
192.168.0.0/31
192.168.0.0/32
So, you see there's a big difference.
HTH, Tim
----- Original Message -----
From: "marc van hoof" <mvh@marcvanhoof.com>
To: "ccie2be" <ccie2be@nyc.rr.com>
Cc: "Cisco Net" <network.cisco@gmail.com>; "Group Study"
<ccielab@groupstudy.com>
Sent: Thursday, November 04, 2004 10:54 PM
Subject: Re: Prefix lists differences ?
> so what you're saying is that if you don't specify the ge xx le xx, it
> means that you are specifying a minimum mask length ?
>
> seems odd, but i'll believe it...
>
> basically that would mean that
>
> ip prefix-list 10 permit 192.168.0.0/24
>
> is the same as
>
> ip prefix-list 10 permit 192.168.0.0/24 le 32
>
> ??
>
> on this topic, do people remember the days before prefix-lists, where you
> HAD to use extended ip access lists for route filtering, and the
> "destination address/mask" of the extended acl referred to the mask of the
> route ?
>
> it was never any fun to see:
>
> access-list 100 permit 192.160.0.0 0.0.0.255 255.255.255.0 0.0.0.255
>
> cheers,
> -marc.
>
> On Thu, 4 Nov 2004, ccie2be wrote:
>
> > They're the same.
> >
> > The slash 24 in the 1st prefix list means the 1st 24 bits of the network
> > address must match and the ge 24 le 24 means the net mask must be
exactly 24
> > bits.
> >
> > In the 2nd prefix list, when you don't have either ge or le, then the
/24
> > refers to both the network address and the net mask.
> >
> > HTH, Tim
> >
> > ----- Original Message -----
> > From: "Cisco Net" <network.cisco@gmail.com>
> > To: "Group Study" <ccielab@groupstudy.com>
> > Sent: Thursday, November 04, 2004 10:20 PM
> > Subject: Prefix lists differences ?
> >
> >
> >> Hi
> >> Is the meaning of the following 2 Prefix lists are same ?
> >> -ip prefix-list ONE permit 100.100.100.0/24 ge 24 le 24
> >> -ip prefix-list TEO permit 100.100.100.0/24
> >>
> >> I thought both are same.. What do you think ?
> >> Regds
> >> Cert
> >>
> >> _______________________________________________________________________
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> >
> > _______________________________________________________________________
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