From: Shine Joseph (shinepjoseph@iprimus.com.au)
Date: Sat Apr 05 2008 - 15:57:44 ART
Athaide,
In the example provided, there is no difference in either prefix list. You
are essentially saying match the first 23 bits and you need a subnet mask of
ge 24 and le 24(which is 24 only).
The solution guide says match the first 23 bits with a subnet mask of le 24.
Here in this case it can only be 24.
But, look at this example:
ip prefix-list FILTER seq 10 permit 28.119.16.0/22 ge 24 le 24
Vs
ip prefix-list FILTER seq 10 permit 28.119.16.0/22 le 24
The first one is saying match the first 22 bits with a subnet mask of 24
only. In this case the matches are:
28.119.16.0/24
28.119.17.0/24
28.119.18.0/24
28.119.19.0/24
Whereas, second one is pointing to match the first 22 bits and the subnet
mask can be le 24. That means, you the prefixes can have a subnet mask of
either 23 or 24. In this case the matches are:
28.119.16.0/23
28.119.16.0/24
28.119.17.0/23
28.119.17.0/24
28.119.18.0/23
28.119.18.0/24
28.119.19.0/23
28.119.19.0/24
HTH,
Shine
-----Original Message-----
From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On Behalf Of
Athaide, Dwayne
Sent: Sunday, 6 April 2008 2:16 AM
To: groupstudy
Subject: Prefix list question
If I want to match the following Subnets in a prefix list
28.119.16.0/24
28.119.17.0/24
My answer
ip prefix-list FILTER seq 10 permit 28.119.16.0/23 ge 24 le 24
SG
ip prefix-list FILTER seq 10 permit 28.119.16.0/23 le 24
Please comment
thanks
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