[address-policy-wg] IPv6 PI for profit, webhosting and route deaggregation

* Nick Hilliard:

> You can certainly do this with lookup engines.  Problem is that if you
> do it, you're breaking the deterministic rib->fib relationship model
> and replacing it with a nondeterministic system, which will probably
> work very well in almost all situations, but which has corner cases
> which fail catastrophically once you run out of lookup engine bits.

I'm not convinced.  The TCAM data structure have no relationship with
the RIB anymore (and the compilation process has not always been
bug-free), either.  Aggregation is just a table mangling that could be
performed in a transparent fashion.

It's an interesting question if you can implement efficient deletes
with aggregation.  But then, you could fake that with a brute-force
approach.

> Looking at it another way, automatic route aggregation creates
> overcommit between the RIB and the FIB.  If that overcommit charge is
> exercised, things will break horribly.

I think the point is to push it so far away that you won't hit it.
There are always some limits.  The important question is whether you
encounter them during (reasonable) life-time of the device.

In any case, I would expect that current TCAM-based implementations
could be exhausted before their nominal capacity is reached with a
carefully crafted list of routes.

-- 
Florian Weimer                <fweimer at bfk.de>
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