How to Filter Prefixes with Distribute-list

Lessons Discussion
7

Hi Rene,

I had a question on the Design and efficiency portion here.

We can place access-list on “in” or “out” I looked up the following which says standard access list should be placed near destination.

Standard Access Control List (ACL) filters the traffic based on source IP address. Therefore a Standard Access Control List (ACL) must be placed on the router which is near to the destination network/host where it is denied. If we place the Standard Access Control List (ACL) near to source of the traffic, there is a chance for denial or other legitimate traffic from the source network to some other network.

https://www.omnisecu.com/cisco-certified-network-associate-ccna/where-should-a-standard-access-control-list-acl-be-placed.php

I also looked up the extended:

Extended Access Control List (ACL) can filter the traffic based many factors like source IP address, destination IP address, Protocol, TCP or UDP port numbers etc.

Since an Extended Access Control List (ACL) can filter the IP datagram packet based on the destination IP address, it must be placed on the router which is near to the source network/host. If we place the Extended Access Control List (ACL) near to destination, the unwanted traffic may consume the bandwidth till destination, and the the unwanted traffic will get filtered finally near destination.

https://www.omnisecu.com/cisco-certified-network-associate-ccna/where-should-an-extended-access-control-list-acl-be-placed.php

However, what is best practice?? what saves the CPU the most work? I mean it almost seems to me if I placed ACL on the source R2 in your example so that it did not have to even send the traffic I save processing on both R2 and R1 which is more efficient.

also since this is only applied to EIGRP it will not effect other traffic anyway. So the rule of the standard acl would not seem to apply here so it seems like you could break that rule for best interest of the efficiency and use a standard.

However, you could use a extended as well here if you wanted. so another question I have in addition to those already asked is does the extended access list cause more work than the standard to the processor?

what is best practice here that will put the least load on our routers?

Also what is best performance and architect wise: distribution ACL, prefix, or route map?