As we squeeze IPv4 address space ever further, we ought to revisit the question of how prefixes longer than a /24 propagate across the internet. The obvious risk with longer prefixes is the potential for an explosion in routing table sizes. At the same time, ARIN has an address block from which it will allocate blocks as small as a /28. In the last few years, RIPE NCC has been actively monitoring how far prefixes from this block propagate, to understand the implications of advertising and routing long prefixes. Since October 2014, they have been advertising two IPv4 /25s and two IPv4 /28s. In this article, they review how things have (or have not) changed over the years.
Submitted by Mirjam Kühne