Sander Steffann wrote:
i suspect that, as multi-homing continues to grow and ipv4 space fragments to be used in core-facing nat[64]-like things, a decade from now we'll see the boundary move to the right.
Maybe, if the equipment can handle the number of routes. I actually see two opposing things: the scarcity will require more fragmentation with smaller fragments, which requires less strict filtering.
The problem is not prefix length (it is a problem if >32, which is the case with IPv6) but the number of routes, which grows because of not fragmentation but poor way of multihoming through routing. Note that if IPv6 will be as popular as IPv4, it has almost equal number of routes for multihoming.
On the other hand the fragmentation will already start with e.g. /20s being fragmented into /24s. That might already cause problems for current hardware, which might cause people to filter more strictly. Unfortunately my crystal ball is broken at the moment.
Considering that a fast cheap 18bit 16M entry 1 chip SRAM has been available for many years, route vendors do not have to deploy slow and complicated logic for route look up, unless they want to make IPv4 route look up as slow as that of IPv6. Even 4G entry will not be a problem, except that it may cause BGP update computation slower. Masataka Ohta