Robin and I have had a few rounds of text revisions. Since the deadline is fast approaching, here is my latest version.

Lixia
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Ivip Critique

Looking at 1000 feet level, Ivip shares the basic design approaches with
LISP and a number of other Map-n-Encap designs based on the core-edge
separation.  However the details differ substantially. Ivip design takes
a bold assumption that, with technology advances, one could afford to
maintain a real time distributed global mapping database for all
networks and hosts. Ivip proposes that multiple parties collaborate to build a mapping distribution system which pushes all mapping information and updates to local, full database query servers located in all ISPs within a few seconds. The system has no single point of failure, and uses end-to end authentication.

"Real time, globally synchronized mapping database" is a critical assumption in Ivip. Using that as a foundation, Ivip design avoids several challenging design issues that LISP team has studied extensively, which include (1) special considerations of mobility support which adds additional complexity to the overall system; (2) prompt detection of ETR failures and notification to all relevant ITRs, which turn out to be a rather difficult problem; and (3) development of LISP-ALT lookup sub-system. Ivip assumes the existence of local query servers with full database with the latest mapping information changes.

However to be considered as a viable solution to Internet routing scalability problem, Ivip faces two fundamental questions. First, it is an entirely open question whether a global-scale system is able to achieve real time synchronized operations as assumed by Ivip. Past experiences suggest otherwise.

The second question concerns incremental rollout. Ivip represents an ambitious approach, with real-time mapping and local full database query servers - which many people regard as impossible. Developing and implementing Ivip may take fair amount of resources, yet there is an open question regarding how to *quantify* the gains by first movers - both those who will provide the Ivip infrastructure and those which will use it. Significant global routing table reduction only happens when a large enough number of parties have adopted Ivip. The same question arises for most other proposals as well.

One belief is that Ivip's more ambitious mapping system makes a good design tradeoff for the greater benefits for end-user networks and for those which develop the infrastructure. Another belief is that this ambitious design is not viable.

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