On 23/02/2017 03:41, Job Snijders wrote: ... > Why publish a document that conflicts with (almost) every deployed > global IPv6 backbone? This would be a farce. Job is correct, and I think the document editor can find one of the various proposed formulations that avoids the farce. Nobody is saying that /64 isn't extremely widely used where it's appropriate to have a portable fixed length IID. Set the default at 64 and trust operators to change it where they need to. That's realistic. Brian