IP Prefix list

Unanswered Question
Feb 6th, 2007

what is the main difference between IP Prefix list and Access-list with BGP?

its much better to understand the advantages and disadvantages between the both... i am looking for some good explanation? i also want the various option of the ip prefix list command for further referance...?

i also want some basic overviews of the various map command used in BGP for the route selection and advertisement manipulation...



I have this problem too.
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royalblues Tue, 02/06/2007 - 06:56


Prefix list offers more flexibility in editing as well as in defining the range of mask lengths

eg. you could have a single prefix list which filters a subnet x.x.x.x/21 le 24. The same would require multiple access-list statements.

Significant performance improvement in loading and route lookup of large lists

Support for incremental updates

Filtering using extended access lists does not support incremental updates.

Though with new IOS releases we can edit the access-list

The command-line interface for using access lists to filter BGP updates is difficult to understand and use, since it uses the packet filtering format.

Eg. access-list 101 permit ip host host which is a slight deviation from the traditional access-lists

?Greater flexibility

In regard to your second question, the following map commands are available while advertisement

route-map, suppress-map, attribute-map & advertise-map

HTH, rate if it does



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