Not that this is really all that NANOG relevant, but if one checks into the archives on the NANOG and RIPE mailing lists, you will find that after lots of discussion, I agreed with Daniel Karrenberg and many others that /19s were eminently reasonable MAXIMUM prefix lengths for globally-visible NLRI. A minimum aggregation boundary leading to no prefixes larger than 18 bits is desirable, and any aggregation that leads to even shorter global prefixes is a big plus for scalability. Consequently, just to repeat myself, /19s for everyone meeting registry requirements is probably just fine. Now let's eliminate globally visible /24s. All of them. ESPECIALLY the historical stuff in the swamp and toxic waste dump. BTW, this probably can serve as notice to people that the step from proxy aggregation of long prefixes to outright lNAT for offenders is not that far in the future... Of course, the plus then is that people at the edges can be as sloppy as they want wrt routing announcements; from the perspective of large chunks of the topology (peers' and suppliers' networks, for example), even rather heavily meshed networks could and will appear to be neatly aggregated into PA address space. Sean. P.S.: Those vendors who are crowing about flow-directed shortcuts for IPv4 would be wise in investing in other flow-directed technologies, such as lNAT, intrusive web caching and redirection, and the like. I am fairly confident that the near future will bring a popular recognition among large transit providers (that is, your initial market) of the Internet as a services-based network with congestion avoidance principally performed at the edges, with unknown spaghetti (odd IP topologies, address and protocol translations and gatewaying, etc.) in the middle. All this nonsense about addressing MUST go away, and an ability to stage migrations to post-IP transport protocol(s) is also very handy. Developing a mindset wherein IP itself is not necessarily end to end, IP addresses may change relative to topology, and may change over time is a really keen way of accomplishing that.