Quoting RFC2860 [Re: I-D Action:draft-azinger-scalable-addressing-00.txt]

[Fred Baker]

On Sep 28, 2010, at 6:42 AM, David Freedman wrote:

> Excuse my ignorance on the subject, but I thought the purpose of L/I was
> to only route locators on the "internet" and to route "identifiers" (i.e
> belonging to services/people) via an overlay (but perhaps I've had my
> head in the LISP cloud for a while)

That is certainly the LISP view of it.

The statement of the concept originates from the NIMROD architecture proposed by Noel Chiappa in the early 1990's. The premise was that the network was composed of a number of networks, which were described using "maps", which is to say "bags of addresses with attributes and inter-map interconnectivity"; that is recursive, so one map might summarize a number of other maps. The description of an address built on the experience in XNS and related protocols (as opposed to DECNET IV, which used a machine identifier and routed to it, and as opposed to IPv4, which identifies an interface and embeds location and identity into the address) with explicit representation of identity and location separately. You might read RFC 1992 for a deeper discussion of that.

GSE, which ILNP and NAT66 are based on, instead of creating a tunnel overlay as LISP does, treats the IPv6 prefix as location and the EID as identity. Like IPv4, IPv6 routes to an interface; unlike IPv4, it strongly distinguishes between location and identity in that sense. The thing I wish was there, and really isn't in a coherent manner although HIP takes a stab in this direction, was an identity for a set of processes, what today nearly 20 years later we instantiate on a virtual machine.