Thomas Narten wrote: > Keith Moore <moore@xxxxxxxxxx> writes: > > >> Sooner or later, routing scalability will be a problem in IPv6. When >> that happens, each network will pick some means to decide which prefixes >> get advertised within its network and which get filtered. It's not >> rocket science to guess that networks will favor their own customers, >> the networks with which they have explicit agreements, and the networks >> from which their customers derive the most value. That probably puts >> most ULAs and PIs fairly far down in the preference list. >> > > Actually, my read of arguments coming from those opposed to ULAs is > that a good number of folk are worried that the some, if not many, > ULAs would be pretty high up on the preference list. I.e., those > hosting content that has become popular. And owners of those services > will simply go to ISPs and say "route this, or I'll find someone else > who will". And the sales and marketing departments of many ISPs will > fall over each other to be the first to say "why certainly we'd love > your business". And then the simple notion of filtering "all ULA > space" goes out the window and we have huge mess, that involves even > more pressures to accept more routes (despite the limitations on > technology), etc. > > You may disagree with that scenario, but it is one that does concern > people in the operational community and is one reason why the proposal > is currently wedged. > Actually I don't disagree with the scenario at all; in fact I think it's exactly what I envision. I just don't see why it's such a horrible thing. What I see as happening when the owners of those services go to ISPs and say "we'd like to have these ULAs be routed" is this: The ISPs say "Great, and we'd love to route them for you. However, as we are sure you know, routing table space is scarce, and routing updates are expensive, and ULAs aren't aggregatable. So it costs a lot to route them, not just for us but for other ISPs also. There are brokers who lease routing table space in ISPs all over the world, and they'll sublease a routing table slot for your ULA prefix - for a price. But you'll be competing with lots of services for a small number of routing table entries, and they go to the highest bidders. " "On the other hand, it appears the particular services that you are offering to the general public would work just fine with PA address space. Furthermore, we'll be happy to offer you our "graceful transition" (tm) service in our contract with you, so that when the term of our contract comes to an end, we'll continue to accept traffic at your old PA addresses and tunnel that traffic to your new addresses for a specified period of overlap - basically the length of your DNS TTLs for those addresses. You can still use ULAs for your internal traffic and - via bilateral agreement - for traffic with other sites. We'd be happy to arrange tunnels to those other sites for routing traffic to and from your ULAs. Or if those destinations are our customers, we'll route those ULAs natively - we just won't advertise them to other networks that we know will filter them. But a lot of sites prefer that their ULAs not be advertised on the public Internet because that lessens the exposure of their non-public services to miscreants." Keith _______________________________________________ Ietf@xxxxxxxx https://www1.ietf.org/mailman/listinfo/ietf