David Conrad wrote:
How do you believe folks will do traffic engineering?
This is an interesting point which occurred to me as I was writing my last email. Outside as-path prepending, I don't have a good answer. Where the relevant organisations have multiple connections to the same upstream, it can be managed using no-export subnet announcements alongside the main supernet announcement. But where there are multiple upstreams involved this will, of course, not work. AS path prepending will continue work to the extent that it does today, which is to say not very well. But the point remains. The default LIR allocation size is /32, which allows for 65K /48's. That is a large number of distinct networks, and will easily satisfy the long-term requirements of small to medium sized ISPs, which - I am going to speculate - comprise the bulk of both AS's and prefix announcements. And if the recommended assignment size were to be changed from /48 to /56 - again allowing ample block size for many organisations, that would optimise address space utilisation further, making a /32 allocation last much longer than previously. Nick