Although I always cautioned when ANY hierarchical routing was accused to cause a stretch ratio =3, I would be curious to hear from stretch experienced researchers what they think about the stretch ratio in case of LISP/ALT.
( I cautioned because of a different and btw really virtual topology in mind; LISP/ALT employs a real and not virtual topology of tunnels).
Could a relationship between stretch and mapping churn exist like:
The less ETRs, the less mapping churn, but the greater the stretch ratio!
Resp. a smaller stretch value can only be achieved by more ETRs and more EID-RLOC propagation, i.e. more update churn, i.e. less solving the scalability problem ?