On 13 nov 2007, at 2:36, Margaret Wasserman wrote:
I think that Geoff Huston has made the same (or a similar) argument when he has indicated that it is architecturally unsound to associate routing properties with a specific address block. There is no inherent guarantee that any registry-assigned address block will be routable (you need to arrange for routing with your ISP), so there is no need to create a new registry-assigned address block to remove that non-existent guarantee.
When ULAs in general were under discussion some years ago, I repeatedly posed the question whether ULAs should be considered unroutable by design or unroutable because of limitations in routing technology. I never got an answer.
In practice, what are you going to do when you do a DNS lookup for some random domain name and you get a ULA address? Ignore it because you know it's unreachable? Try to send a packet anyway? Choosing the wrong action here probably means you'll have to suffer a timeout and retry with a different address or fail. (The only thing worse than failure is taking a lot of time to fail.)
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