Hello Justin
Rene created the R1_L0_PERMIT access list with a permit statement for the 192.168.0.0/24 subnet. This was then referenced by the TEST_3 route map with a deny statement for matches to this access list.
So this route map is applied to the distribute-list of EIGRP. Now a router sends the following four subnets via EIGRP and they are “filtered” through this distribute list:
192.168.0.0/24
192.168.1.0/24
192.168.2.0/24
192.168.3.0/24
When they go through, the first is matched by the access list, and the route map says “deny” for this, so it is not allowed. The second is not matched by the access list, but is matched by the implicit deny statement at the end of the route map, and is therefore denied. The same happens to the other two subnets.
Now if we add a permit statement to the end of the route map to match everything, the result will be that the route map will allow everything except for whatever the first statement denies. So with this permit statement, the distribution list will deny the 192.168.0.0/24 subnet, but will allow everything else, thus the other three subnets are sent through.
The final route map and access list that @ReneMolenaar displays at the end (without the typo) is the following:
route-map TEST_3 deny 10
match ip address R1_L0_PERMIT
route-map TEST_3 permit 20
It depends on how the route map is configured. Remember that there is an implicit deny at the end of all route maps. If there is a permit statement at the end like we configured above, and the match condition doesn’t match anything, then it is as if the route map does not exist. If the match condition does not match any address and there is no permit statement at the end of the route map, then the implicit deny will cause deny everything.
Thanks for pointing the typo out, I will let Rene know to fix that.
I hope this has been helpful!
Laz