Thus spake "Daniel Senie" <dts@senie.com>
At 07:11 PM 11/24/2004, Owen DeLong wrote:
Yes, they do. However, today, with RFC-1918, we can at least give them a good technology reason why not. With ULA, we have no such defense... There's simply no reason a unique prefix can't be routed.
So with unique address blocks, blocks that should not appear in the GLOBAL routing table, companies could use those prefixes for private peering all over the place. This sounds like a great idea for companies cooperating in commerce operations. Of course all that private traffic might traverse a network that bypasses the ISPs and NSPs, or perhaps runs over private virtual circuits (MPLS, Frame, ATM or whatever the popular choice is for such circuits that month).
While from a network operator's perspective, this might be a disaster, it's an enabler for corporate networks, and there's no reason to discourage it.
I don't see much argument against the idea of ULAs iff they actually remained local.
If you are a network provider, then filter the entire prefix block and any longer prefixes announced. Please, though, stay out of the way of private interconnectors who've been asking for years to have unique space so they can reliably talk with one another.
If I understand the fear of Owen, Leo, and others, presumably if a couple tier 1s decided (intentionally or not) to route ULAs, then other ISPs would be forced by market conditions (i.e their customers) to route them as well... For instance, what would happen if Google were only reachable by ULAs? I think the WG would welcome any input that would help prevent this from happening. One thought would be to require router vendors to make it so each ULA prefix to be allowed over BGP must be configured individually instead of a single flag to allow all of them. S Stephen Sprunk "Stupid people surround themselves with smart CCIE #3723 people. Smart people surround themselves with K5SSS smart people who disagree with them." --Aaron Sorkin