Prefix versus Access-list when distributing routes

chrisdaly · ‎09-15-2008

When advertising/distributing/redistributing routes, is there a general rule of thumb as to when to use an access-list and when to use a prefix-list?

Edison Ortiz · ‎09-15-2008

It depends on the requirements, if you are asked to deny/permit odd/even networks, then ip access-list is the tool to use.

If you are asked to deny/permit a range of networks you have more flexibility with ip prefix-list

For instance,

ip prefix-list NETPRO deny 10.0.0.0/8 ge 25

This ip prefix list is configured to deny routes from the 10.0.0.0/8 network that have a mask length that is greater than or equal to 25 bits

Kind of hard to do the same while using ip access-list

Know both tools and you make the case which one to use more effectively. I've also read ip prefix-list are processed faster by the hardware.

HTH,

__

Edison.