DHCPv6 PD oddity with client changing prefix size.

Simon Hobson dhcp1 at thehobsons.co.uk
Tue Aug 15 07:08:33 UTC 2017

Can't help with the problem, but an observation ...

Tim DeNike <tim at denike.us> wrote:

> By default we give users a /64 but will allow them to request a /60 or /56.

Why not a /56 by default, and a /48 on request ?

There's an endless discussion over on the V6 Ops list about various things - and a common "discussion point' is whether to relax the /64 that's more or less hardcoded into several standards documents. One of the arguments against relaxation is that it imposes a minimum on ISPs who would otherwise start offering a /96, or a /120, or ... and we'd soon be back to users forced into using NAT.

And there is work in progress (eg to make home users secure by default - eg by separating the IoTat stuff from their main network) that will require multiple /64s.

Don't have a reference, but AIUI, anything less than /56 is "just wrong", and /48 is preferred as a default allocation.

But at least you are offering IPv6 - my ISP ran trials a few years ago and has since gone "very quiet" on their plans :-(

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