I think that before we decide whether we are for or against a locator/identifier split, we need to pick a single definition for what the locator is and a single definition for what the identifier is. LISP refers to the IP address of a certain router as a "locator" and the IP address of an end system as the "identifier", and splits them by making them different layers in a tunnel-like (map/encapsulation using an ip/ip tunnel header) overlay network. ILNP and other GSE-derivitives make the IP prefix the "locator" and the IP End Point Identifier the "identifier", and split them in the sense that the identifier is consistent end to end but locator is fungible at stated points in the network according to a set of rules and therefore has different degrees of locality.
I personally am in favor of the latter (ILNP ideally, http://tools.ietf.org/id/draft-mrw-behave-nat66 as a fall-back position which I suspect will be easier to deploy as it does not require host changes), and not in favor of the former. My reasoning is that the ILNP model is a win-win between edge and transit networks, giving them both a direct solution to a problem that they have said publicly and loudly that they would like to see fixed, while LISP is (in my opinion) not. The problem we set out to solve recognized a fundamental difference of opinion being battled out in the RIR communities. Edge networks, as a class, want to be independent of their upstream networks. They want to be able to change upstreams without a significant level of effort in renumbering or changing their routing. They generally don't want a large route table, and generally solve this using default routes to their upstreams, potentially tuned with a few more-specifics for key business partners. Their solution in IPv4 is either IPv4/IPv4 NAT, which has operational problems for several classes of applications, or PI addressing, which explodes the route table by enumerating the edges. Transit networks, as a class, prefer or don't object to having their customers captive to them, and want a route table of a manageable size. For them, a PA allocation - allocation that enumerates only the points where the edge attaches to the transit core - achieves that goal. I prefer the GSE model, instantiated in ILNP, because it gives the edge networks the relative simplicity of management and independence they seek - their network appears to them as if it were PI - while giving the transit networks the relative simplicity of management and route table effects of a totally or mostly PA network. Both sides win. The route table in the backbone enumerates the folks in the world that have AS numbers, whether they are truly ISPs or whether they are simple complex edge networks. The edge networks are independent of their upstreams with the added benefit of being able to address systems in their own and other edge networks statelessly, uniquely, and exactly, just as if addressing were truly end to end, and allows for predictable load sharing across DMZs in parallel, which IPv4/IPv4 stateful NAT does not. I don't believe that LISP does that. It does simplify the transit domain - addressing in that domain is PA. Outside the transit domain, addressing remains PI, and the complexities implied by that are moved from the transit domain (which has expertise in handling that) to the edge (which does not). I think it makes the network harder for the edge to attach itself to without expert help. BTW, I have a similar opinion of shim6, although the wording of the argument is different. shim6 makes the entire network PA, which is good for the transit networks, and makes multihomed edge networks bear the complexity burden of maintaining routing for each prefix they use throughout their networks. The edge, I fear, lacks either motivation or expertise to offload the complexity from the transit core. As to your proposed questions, I think they make a false assumption - that we have four options on the table: - one with a hierarchical system and Global/universal characteristics, - one with a hierarchical system and local characteristics, - one with a flat system and Global/universal characteristics, and - one with a flat system and local characteristics. I'm not sure the proposals are malleable in that way. On Jul 25, 2010, at 5:02 PM, Toni Stoev wrote: > Researchers, > > I think we must not attack each other personally. Nor even each other's views. > We need to find the best solution each of the design goals. > > Here we talk about identity/location split. Robin is against. Most but seem > to be for. > So with the identity/location split we encounter identifier uniqueness. > Whether it has to be global/universal or just local. Some hesitate about > this; others, like me, take universal uniqueness for natural. > Next question: Uniqueness system is to be hierarchical or flat? Any arguments > on flatness side? But there is a ready-made solution. Is it reliable? > Are we going any further with this ambiguity? > > I propose this approach: Let's answer the questions the reverse way. > > 1. Hierarchical or flat uniqueness system? > 2. Global/universal or just local uniqueness? > 3. Shall we make identity/location split? > > Good will > Toni > _______________________________________________ > rrg mailing list > [email protected] > http://www.irtf.org/mailman/listinfo/rrg http://www.ipinc.net/IPv4.GIF _______________________________________________ rrg mailing list [email protected] http://www.irtf.org/mailman/listinfo/rrg
