> On Jun 15, 2020, at 10:56 AM, Tony Przygienda <[email protected]> wrote: > > PNNI had transit areas in hierarchy working but the trick was connection > setup cranck-back. Such a thing would work for RSVP or any of the stateful > connection setups but alas, this is not fashionable right now. Unfortunately, > generic hierarchy with reachability summarization ends up with very > sub-optimal routing or black-holing on aggregates since we cannot "back-off" > generic LPM packet forwarding when we realize we're @ a dead end due to > aggregation. To prevent bi-furcation of topology or transit horizontals > several solutions exist, one of which (configure hierarchy statically > everywhere) the current draft has in now but alas, the topology is star of > stars (you can actually see CLOS conceptually as something like this as well > ;-)
Hi Tony, The modern solution of choice is to relegate all of the traffic engineering to an out-of-band controller that no longer operates in real-time and has the scale to span levels and areas. Tony
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