On Apr 18, 2011, at 12:18 PM, Jeff Wheeler wrote:
2011/4/18 Lukasz Bromirski <lukasz@bromirski.net>:
LISP scales better, because with introduction of *location* prefix, you're at the same time (or ideally you would) withdraw the original aggregate prefix. And as no matter how you count it, the number of *locations* will be somewhat limited vs number of *PI* address spaces that everyone wants
I strongly disagree with the assumption that the number of locations/sites would remain static. This is the basic issue that many folks gloss over: dramatically decreasing the barrier-to-entry for multi-homing or provider-independent addressing will, without question, dramatically increase the number of multi-homed or provider-independent sites.
Done properly, a multi-homed end-site does not need to have its own locator ID, but, could, instead, use the locator IDs of all directly proximate Transit ASNs. I don't know if LISP particularly facilitates this, but, I think it would be possible generically in a Locator/ID based system.
LISP "solves" this problem by using the router's FIB as a macro-flow-cache. That's good except that a site with a large number of outgoing macro-flows (either because it's a busy site, responding to an external DoS attack, or actually originating a DoS attack from a compromised host) will cripple that site's ITR.
The closer you move the ITRs to the edge, the less of an issue this becomes.
Owen