Implementations/suggestions for Multihoming IPv6 for DSL sites

Jeff Wheeler jsw at
Mon Apr 18 19:18:46 UTC 2011

2011/4/18 Lukasz Bromirski <lukasz at>:
> 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.

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.

In addition, the current negative mapping cache scheme is far from
ideal.  I've written a couple of folks with a provably superior scheme
(compared to existing work), and have received zero feedback.  This is
not good.

> We may of course argue that the current routers are pretty
> capable in terms of processing power for control-plane, but

We agree that the ability to move tasks from the router to an external
control plane is good.  BGP may get better at this as time goes on,

Jeff S Wheeler <jsw at>
Sr Network Operator  /  Innovative Network Concepts

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