Jay, Each IPv6 /64 should be thought of as the same as an IPv4 /32? That seems a tad wasteful. A single /64 has billions of times more addresses than the entire IPv4 address space. It is enough for any conceivable subnet. There are also billions of /56 prefixes available, so no ISP customer would ever exhaust those either. A customer can get as many /56s as they need. The RFC seems to be concerned with aggregation efficiency, and while that may be a concern someday, so far computer and memory capacity has far outstripped prefix growth in the default-free zone. If you can explain why a /64 would ever not be enough for a single subnet, I’m willing to listen. -mel On May 15, 2024, at 9:52 PM, Jay Acuna <mysidia@gmail.com> wrote: A /64 is not "enough" period. Each IPv6 /64 should be thought of as the same as an IPv4 /32. The RFC is still relevant. You are able to be allocated IPs justifying 8-bits per customer (/56) and customers should expect that /56 be the minimum delegated by their providers. The prefix delegation for IPv6 is based on number of separate /64 subnets they might have a reason to use (which can be for many reasons including security and division of traffic and use cases), Not number of individual hosts they may have, since subnet divisions more granular than /64 are not possible. On Wed, May 15, 2024 at 8:17 AM Mel Beckman <mel@beckman.org> wrote: I never could understand the motivation behind RFC3531. Just assign /64s. A single /64 subnet has 18,446,744,073,709,551,616 host addresses. It is enough. Period. -mel -- -J