Maybe a better solution would be a backup organization that announces the /32 if it disappears and tunnels the packets to the customers over the secondary ISPs.
I'm not sure if I got your point here. Are you suggesting that another ISPIt could. An ISP could set up a related, but independent backup network. Since this network would only have to peer or buy transit in a couple of locations and maintain a bunch of tunnels, this wouldn't be too costly.
has to take over all the traffic for the disconnected ISP? I hardly believe
this will ever happen in the real world :)
If the routers must be able to handle the full set of unaggregated prefixes anyway, why bother aggregating?
Memory scales linear so that's not the biggest problem. Processing scales worse than linear so in the end that will be the downfall of huge routing tables.Well, a large routing table is only a memory/msg-size problem.
This isn't a protocol issue. Vendors can implement this today, but they choose not to.A large forwarding table also slows down the forwarding process. With automatic aggregation at least the latter is solved.