Randy Bush wrote: > Geoff: > >>> and this case, although not common, has been visible in the routing >>> table already >>> > Randy: > >> oh? and how do you detect it? how many are there? how much of a real >> problem is it? >> > > so i had a three hour drive from seeing kids in portland to the exciting > westin colo in seattle. i did not even make it through the neil young > on my ipod. but i kept thinking of how one could test or demonstrate > your assertion. perhaps neil scrambled my thinking, but it did not even > get to winterlude. > > for each prefix in some routing table, rv, dump of one of my routers, > whatever, see if that prefix can be decomposed into two or more prefixes > which one can demonstrate are 'given' to the announcing asn by two or > more different would-be certificate authoritiess, e.g. rirs or disparate > delegatees of rirs. > > i could not really see how to do this for other than the case where the > prefix can be shown to be in the delegation registries of two rirs. > > please give us one example which supports your assertion, or whack me > with a clue by four about how one could better test/demonstrate your > assertion. >
Let me ask Geoff about the specific kinds of scenarios, to simplify things a bit. (I'm curious, too.) Would the visible examples be adjacent prefixes (suitable for aggregation) originated by one specific ASN? Or, would the visible examples be adjacent prefixes from two ASNs, being *proxy* aggregated by a third ASN? Or some other variation involving one or two ASNs? Try as I might, I am unable to figure out any way to split a block more than one way. And for two blocks to be able to be aggregated (without covering other prefixes, i.e. not a proxy aggregate for any third parties), they have to be adjacent. Which means the two entities giving those blocks, would have to give the *whole* block (in both cases) to the recipient, with nothing left over for the giver or the giver's other customers. A=CIDR(x/n) -> B=CIDR(x/n+1) + C=CIDR(x+foo/n+1) RIR split A, gives B to Bob and C to Carol. Bob gives B to Dave, and Carol gives C to Dave. Dave can now join B+C to get A again. Nothing else works, unless B is passed down through Eric, Franz, and Greg, and C is passed down through Harriet, Ian, and James. In each case, without taking anything from B or C. Is this known to have happened, and is it visible in the routing table?? Brian _______________________________________________ sidr mailing list [email protected] https://www.ietf.org/mailman/listinfo/sidr
