Route Filtering with distribute-list

3 ways to filter routes for redistribution :

- Standard ACL
access-list permit ip 10.0.0.0 0.0.15.255

Match 10.0.0.0/20 but also 10.0.0.0/21 .. 21 etc any smaller mask.

To match also the mask use Extended ACL

-Extended ACL
access-list 101 permit ip 10.0.0.0 0.0.0.0 255.255.248.0 0.0.0.0

Match only 10.0.0.0/20

-Prefix-list
ip prefix-list TEST 10.0.0.0/20

But permit to limit a range of valid mask
ip prefix-list TEST 10.0.0.0/20 le 24
It match 10.0.0.0/24 and also 10.0.4.0/22

ip prefix-list TEST 10.0.0.0/20 ge 24
It match 10.0.0.0/24 but also 10.0.0.0/25 ...