Thomas Narten wrote:
Keith Moore <moore(_at_)cs(_dot_)utk(_dot_)edu> 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 mailing list
Ietf(_at_)ietf(_dot_)org
https://www1.ietf.org/mailman/listinfo/ietf