Hi, I would suggest the following:
ip prefix-list test seq 5 permit 0.0.0.0/0 ip prefix-list test seq 10 permit 0.0.0.0/1 ge 8 le 8 ip prefix-list test seq 15 permit 128.0.0.0/2 ge 16 le 16 ip prefix-list test seq 20 permit 192.0.0.0/3 ge 24 le 24 Your solution wouldn't filter out those subnets and aggregates whose netmask falls on a classful boundary. And of course the sequence numbers must be different for each entry. :) Thanks, Zsombor At 07:14 AM 7/10/2003 +0000, Raj Singh wrote: >Classless domain ---------R1----------classful domain > >R1 is the border router between the classless and classful routing domain. >R1 maintains a BGP peering session with the classless routing domain, and >runs a classful IGP with the classful routing domain. The classless routing >domain is originating a default route to R1 via BGP, and advertising >prefixes which are subnetted, aggregated, and classful. Since the classful >routing domain does not support the advertisement of subnets or aggregates, >there is no reason for R1 to accept any of these prefixes in from the >classless domain. Configure an access-list or prefix-list on R1 that will >only allow classful networks and a default route in from the classless >routing domain. This access-list or prefix-list should not contain more >than four entries. > >I think this will work but not sure. Can anyone tell me if this is right? >ip prefix-list test seq 5 permit 0.0.0.0/0 >ip prefix-list test seq 5 permit 0.0.0.0/0 ge 8 le 8 >ip prefix-list test seq 5 permit 0.0.0.0/0 ge 16 le 16 >ip prefix-list test seq 5 permit 0.0.0.0/0 ge 24 le 24 > >Any help is duly appreciated in advance. > >Thanks >Raj Message Posted at: http://www.groupstudy.com/form/read.php?f=7&i=72139&t=72090 -------------------------------------------------- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
