prefix-list vs access-list and these two articles

Answered Question
Sep 25th, 2006

I have read in CCNP curriculum that Cisco says :

" Use prefix lists as an alternative to access lists with many BGP route filtering commands. The advantages of using prefix lists rather than access lists include the following :

1- Significant performance improvement in loading and route lookup of large lists.

2- Support for incremental updates. Filtering by way of extended access lists does not support incremental updates.

3- A more user friendly command-line interface.

4- Greater flexibility ".

But when I read the article below , I could not figure out what does he mean :

" Unlike the IP access-list, which was designed to match traffic, the IP prefix-list was designed specifically with network reachability information in mind ".

Regards

I have this problem too.
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Correct Answer by Richard Burts about 8 years 10 months ago

This link is to a good article by Russ White in the Internet Protocol Journal which includes some discussion of control plane and data plane (forwarding plane). I hope that it will help you to understand these concepts.

http://www.cisco.com/web/about/ac123/ac147/archived_issues/ipj_7-1/high_availability_routing.html

HTH

Rick

Correct Answer by Harold Ritter about 8 years 10 months ago

What this article means is that the prefix-list would be used at the control plane level rather than the forwarding plane level.

For instance you wouldn't use a prefix-list to filter traffic (forwarding plane) as you do with an ACL. The prefix-list is mainly used for route filtering (control plane).

Hope this helps,

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Overall Rating: 4.3 (3 ratings)
Correct Answer
Harold Ritter Mon, 09/25/2006 - 23:14

What this article means is that the prefix-list would be used at the control plane level rather than the forwarding plane level.

For instance you wouldn't use a prefix-list to filter traffic (forwarding plane) as you do with an ACL. The prefix-list is mainly used for route filtering (control plane).

Hope this helps,

zillah2004 Tue, 09/26/2006 - 07:55

((control plane level rather than the forwarding plane level)).

Thanks hritter, could you kindly explain it with more details, because I did not get what is the exact difference, between the control level and the forwarding level ?

Regards

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