Robin, > > Short version: Can anyone explain exactly how LISP-NAT is > supposed to work, what it is useful for (especially > in terms of what it can do which other approaches > can't) and what its limitations are? > > Does anyone argue that LISP-NAT will actually > be useful enough to be adopted? > The LISP Interworking draft explains how LISP-NAT works, and why it is useful. LISP-NAT can be used in conjunction with Proxy Ingress Tunnel Routers, or on its own to enable hosts at a LISP site to exchange packets with hosts at a non-LISP site. Sites using LISP-NAT can on their own decide their hosts from Non-Routable) EID space, while communicating with non-LISP sites via its outside Routable (LISP-R) EIDs. Thus it can be an alternative to using network based Interworking infrastructure. For an interesting discussion of the limitations of NAT in general, you might read: http://tools.ietf.org/id/draft-vogt-address-translation-harmfulness-03.t xt which seems to cover most of the caveats of using NAT. You mentioned in an earlier email that you doubted whether LISP-NAT can be made to actually work, but we have existence proof in the existing LISP network that it can be implemented successfully. I also don't want to be drawn into a debate about the pro's and cons of NAT, except to say that it exists, and is popular for IPv4. Since NAT exists, and can be applied to solve the Interworking problem, the authors decided to include it in the Interworking specification and to experiment with it. -Darrel
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