On 2010-05-02 10:44, Fred Baker wrote: > On Apr 30, 2010, at 4:21 PM, Schwarz Albrecht wrote: > >> Question: If a realm is characterized by reachability, then I would >> assume that an "IPv6 realm" would equate to an "IPv6 routing domain", >> right? > > well, here things get squirrelly. > > Look again at the picture in my original email in this thread: > > ------ ------ ------ ------ > // My \\ // \\ // \\ // Your \\ > /ULA Realm \ / ISP1 \ / ISP2 \ /ULA Realm \ > || || || || || || || || > | +---+ +---+ | | +---+ +---+| > | |Me | |DMZ| ------- |DMZ| |You|| > | +---+ +---+ | | +---+ +---+| > || || || || || || || || > \ / \ / \ / \ / > \\ // \\ // \\ // \\ // > ------ ------ ------ ------ > > |<- my realm ->|<-------- Core Realm ----->|<-your realm->| > > If these were IPv4 routing domains, the counterpart to a ULA would be an RFC > 1918 prefix, and the reason that it wasn't injected in the the relevant ISP's > routing was (beyond contracts and all that) that it would make routing in the > ISP ambiguous: it would be actively bad. In IPv6 routing, the reason that a > ULA is "local" is that the ULA domain doesn't advertise it outside of its > domain and the ISP doesn't accept it if it did. But if they two agreed to > advertise and believe it, there is no substantive reason that they *couldn't* > - it wouldn't hurt anything.
And if Me and You cared to interconnect their networks with a leased line, they could mutually announce their ULA prefixes to each other. This would bind the two routing domains in some way, but they would still be separate autonomous system. Which wouldn't hurt anything either. That's actually why ULAs are (a) unique and (b) of nominally global scope, and it's another reason why the term "IPv6 Realm" doesn't seem useful. Brian > Now, in the default-free zone (to the extent that such a thing really exists > in the core), there are all sorts of places in which we aggregate routing, > disbelieve routes advertised, and choose to advertise or not advertise > routes. That makes it hard to argue that the fact of applying policy to > routes marks off routing domains. I tend to come back to the definition of an > "autonomous system", no doubt made for EGP or BGP but escaping search at the > moment: "a set of networks using a common routing protocol and under common > administration" for a "routing domain" - it is a region in which we can > rationally expect routing to be consistent. > _______________________________________________ > nat66 mailing list > [email protected] > https://www.ietf.org/mailman/listinfo/nat66 > _______________________________________________ nat66 mailing list [email protected] https://www.ietf.org/mailman/listinfo/nat66
