Eszett and IDNAv2 vs IDNA2008

[Eric Brunner-Williams]

> ...  the various try-2008-fail-to-2003 strategies people have talked
> about, which includes the two-lookup approach.  (That two-lookup
> approach is indeed broken in principle, but it might be good enough
> for a transition strategy.)
>   
Andrew,

I've been up part of the night with a child with a sleeping disorder, so 
I'm wicked insufficiently caffinated, but the ARP code (arp_rtrequest(), 
and the subsequent call paths) in *nix (your implementation may differ) 
is/was a two-lookup approach. I recall doing access router (wicked 
rococo access link media types, not a simple fastpath-uber-alles core 
router) where the only mechanism that would result in the service 
discovery required was two-lookup. I expect there are other 
ask-twice-do-once algorithms thriving in the wild.

I appreciate the desire to get the right answer the first time, but 
"broken in principle" needs technical justification, specific to the 
problem domain. If you have the time, and I can wait until SF, could you 
supply the clue by four?

TiA,
Eric