I may have mis-read it (I admit I didn’t read it all that carefully) but I think RFC3531 is talking about the strategy for assigning /64s out of a larger pool (a /56, say). -Adam Adam Thompson Consultant, Infrastructure Services MERLIN 100 - 135 Innovation Drive Winnipeg, MB R3T 6A8 (204) 977-6824 or 1-800-430-6404 (MB only) https://www.merlin.mb.ca<https://www.merlin.mb.ca/> Chat with me on Teams<https://teams.microsoft.com/l/chat/0/0?users=athompson@merlin.mb.ca> From: Mel Beckman <mel@beckman.org> Sent: Tuesday, May 14, 2024 3:13 PM To: Adam Thompson <athompson@merlin.mb.ca> Cc: nanog <nanog@nanog.org> Subject: Re: Q: is RFC3531 still applicable? 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 On May 14, 2024, at 12:54 PM, Adam Thompson <athompson@merlin.mb.ca<mailto:athompson@merlin.mb.ca>> wrote: Not an IPv6 newbie by any stretch, but we still aren’t doing it “at scale” and some of you are, so… For a very small & dense (on 128-bit scales, anyway) network, is RFC3531 still the last word in IPv6 allocation strategies? Right now, we’re just approaching it as “pick the next /64 in the range”, as it all gets aggregated at the BGP border anyway, and internally if I really try hard, I might get to 200 subnets someday. Is there any justification for the labour in doing something more complex like center-allocation in my situation? Worrying about allocation strategies seems appropriate to me if you have 100,000 subnets, not 100. Opinions wanted, please. -Adam Adam Thompson Consultant, Infrastructure Services MERLIN 100 - 135 Innovation Drive Winnipeg, MB R3T 6A8 (204) 977-6824 or 1-800-430-6404 (MB only) https://www.merlin.mb.ca<https://www.merlin.mb.ca/> Chat with me on Teams<https://teams.microsoft.com/l/chat/0/0?users=athompson@merlin.mb.ca>