On Thu, 26 Oct 2006, Tony Li wrote:
It was possible to implement BCP38 before the router vendors came up with uRPF.
Further, uRPF is frequently a very inefficient means of implementing BCP 38. Consider that you're going to either compare the source address against a table of 200,000 routes or against a handful of prefixes that you've statically configured in an ACL.
Isn't that only a problem if you want to run a loose mode uRPF? Given that loose mode uRPF isn't very useful in most places where you'd like to do ingress filtering, this doesn't seem like a big issue.. BTW, I still keep wondering why Cisco hasn't implemented something like Juniper's feasible-path strict uRPF. Works quite well with multihomed and asymmetric routing as well -- no need to fiddle with communities, BGP weights etc. to ensure symmetry. -- Pekka Savola "You each name yourselves king, yet the Netcore Oy kingdom bleeds." Systems. Networks. Security. -- George R.R. Martin: A Clash of Kings