ACLs Filtering Locally Generated Traffic

ACLs filter incoming or transient traffic. They do not filter all traffic that is generated by the local router:

• An inbound ACL checks locally generated traffic.
• An outbound ACL will not check locally generated traffic.

If you want to filter traffic that is generated by the router, it's best to use Control Plane Policing (CoPP).

Links:

https://forum.networklessons.com/t/standard-access-list-example-on-cisco-router/889/22?u=lagapides