Do you *really* want your DNS TTL set down in the same range as the time for a BGP route fall-over?
Q: what is the route convergence time of 'the internet', for any given route? It is certainly larger than BGP route fall-over time. DNS may well not be an ideal protocol for doing this [1]. However, as Howard eloquently posted earlier, I was rather evidencing that BGP isn't the only tool available, and is certainly not the only tool possible. Heh, may be we'll have to go do some work on a new one, or enhance a current one. [1] = you may well find that client stacks are a larger problem.
We usually run with hign TTLs, and drop them down before impending changes. Unfortunately, there's no easy way to do that 24 hours before the backhoe gets there...
So you /could/ always run it low. Look at technologies like ultradns / nominum, to see how this can actually work well. And feed that database (far easier distribution problem) from your reachability information.
Also, if you run BigSite.com and drop your DNS TTL, I *do* pay, because now my DNS server has to hit the network for a look-up for your site - you just added several packets to the transaction.
Ummm, so if X is accessing Y's site, Y pays for some of the network costs, and X pays for some of the network costs. However, at least in this proposal Z (unconnected 3rd party) doesn't suffer - he does suffer from routing table bloat. The suggestion that the users (both source and destination) should pay for performance, rather than the rest of the internet in general, is, of course, shocking to some :-) Alex