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Re: Question about prefix list
From: Wouter van der Vaart <wouter () terrean net>
Date: Thu, 2 Feb 2012 02:43:37 +0100

Hi Ann,

The le parameter can be included to match all more-specific prefixes within a par ten prefix up to a specified length. 
FE: 202.168.136.0/22 le 25 will match 202.168.136.0/22 and all prefixes contained therein with a length of 24 or less.

They appear to be blocking everything with a length longer dan /24 (so /25 /26 etc etc.)

the last line doesn't have this because it's only 1 /24 subnet.

Regards,

Wouter
On Feb 1, 2012, at 15:32 , Ann Kwok wrote:

Hi

I read this prefix list.

Can I know why there is "le 24" after network block in /22 and /21

Why don't have "le 24" after /24?

I also saw another prefix list before. They use "le 32" instead of  "le 24"

What are their different?

ip prefix-list prefix-filter-as100 seq 10 permit 202,168.136.0/22 le 24
ip prefix-list prefix-filter-as100 seq 20 permit 202,22.92.0/22 le 24
ip prefix-list prefix-filter-as100 seq 30 permit 202,21.148.0/22 le 24
ip prefix-list prefix-filter-as100 seq 40 permit 203,178.88.0/21 le 24
ip prefix-list prefix-filter-as100 seq 50 permit 178.88.74.0/24

Thank you so much




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