On Jan 24, 2009, Dino Farinacci wrote:
4 - LISP-ALT's Aggregation implies provider dependence.
This is Christian Vogt's critique:
http://psg.com/lists/rrg/2008/msg00259.html
Not true. Aggregation here is for the EID-prefix. Service providers do
not carry EID-prefixes in their cores so you don't depend on them. The
decoupling of the address creates this. The dependence is now on the
ALT. And if your site resides in a specific region of the world, you
get
your EID-prefixes from that registry. So readdressing your domain
would
only occur if you moved it from one region to another (let's leave
mobile ASes out of this for now).
Dino -
There is a tradeoff between EID portability and path stretch along the
ALT topology, and I believe the tradeoff made in LISP/ALT has been
revised a few times.
Portability of EID prefixes requires that the ALT topology follows
EID-addressing. This leads to potentially longer-than-optimal paths
along the ALT topology. Vice versa, if path stretch is to be limited,
then portability of EID prefixes must be restricted.
According to your email to Robin, LISP/ALT currently makes the following
tradeoff: Portability of EID prefixes is limited geographically in
order to curb path stretch along the ALT topology to the maximum that
can happen within a geographical region.
That's possible, of course. The cost is that networks scattered over
different parts of the world, such as those of enterprises with global
presence, cannot use a continuous address space internally -- even if
they all attach to the same provider.
- Christian
_______________________________________________
rrg mailing list
[email protected]
http://www.irtf.org/mailman/listinfo/rrg
