Joel, Certainly I agree that the text in [LISP] addresses some of the basics of handling overlapping prefixes. I had thought that one point of LISP was to avoid needing to renumber; I believe that in a similar case with IPv4 addresses today, it's not unusual to get the smaller prefix announced.
However, in response to more detailed questions, I keep hearing back assumptions or things that have been discussed on the list and are not captured in a draft. For a protocol like LISP, there are clearly many operational details and assumptions to be agreed upon and that need to be consistent. Last time I looked at the deployment draft, I didn't notice them captured anywhere. Are there plans for such a draft? Alia On Wed, Jun 22, 2011 at 6:49 PM, Joel M. Halpern <[email protected]> wrote: > The normal situation is that an EID block is delegated to an administrative > authority (a company). They use it. > They may use the main block, and use some sub-blocks. That produces "holes" > which are overlapping prefixes. The handling of that is described in the > document. The ETRs which are responsible for the covering EID prefix must > know which blocks are allocated elsewhere. > They have to identify those in the response. > > THe details are spelled out. > > The normal case would be that the division that was sold would be renumbered > into its own or its new parents EID block. After all, they are no longer > part of the original site. The overlapping prefix mechanisms allow for > transition. > > The more extreme case is not permitted. You can not have a LISP EID block, > within which there is a hole which is used as IP addresses but not as LISP > EIDs. (The inner portion can be used as both, but it has to be an EID.) > > Yours, > Joel > > On 6/22/2011 6:32 PM, Alia Atlas wrote: >> >> Dino, >> >> Thanks for your responses - mine are in-line below. >> >> Alia >> >> On Mon, Jun 20, 2011 at 6:19 PM, Dino Farinacci<[email protected]> wrote: > > ... >>> >>> If the site has an EID-prefix of the /16 that is the one it Map-Replies >>> for. >>> We have rules in section 6.1.5 "EID-to-RLOC UDP Map-Reply Message" on how >>> to >>> send Map-Replies when there are overlapping EID-prefixes and there has >>> been >>> much discussion on this mailing list about it. >> >> I agree that there's been lots of discussion on the list. Capturing >> the decisions made >> into the draft would be good practice, IMHO, and ensure it has been >> resolved. >> >> Can an ETR have an prefix which has a hole in it? What happens if the >> ETR does not >> know the correct RLOCs to use for that hole (since it isn't owned)? >> >> I'm thinking of a case where initially there is a LISP site with a >> /16. Then, part of that >> company is sold along with the /24 that is used in that division. >> Now, can the original >> site advertise the /16 with a hole? How would it do that? >> >> The problem here is that the ETR does NOT KNOW the correct locator-set >> for the /24 hole >> that has been sold off. >> >> > _______________________________________________ lisp mailing list [email protected] https://www.ietf.org/mailman/listinfo/lisp
