Re: [v6ops] I-D Action: draft-ietf-v6ops-unique-ipv6-prefix-per-host-07.txt

[Brian E Carpenter <[e-mail]>]

On 17/08/2017 12:24, DY Kim wrote:
> Does this ‘unlimited devices behind the host’ include the following case?
> 
>   - A host gets a /64 prefix.
> 
>   - The host runs for itself an internal ‘Unique-IPv6-Prefix-per-Host’ so that it hands out a /96 prefix to each internal device.
> 
>   - In effect, this comes down to /96 prefixes and 32-bit IIDs.
> 
> Technically, there’s no reason why this cannot be done, I’d assume. However, would this be forbidden in the sense of the current and related std track documents?

It's forbidden by the fact that RFC4291 states that the IID length is 64. Clearly that applies to SLAAC; it's a bit less clear whether it applies to DHCPv6. But the privacy related RFCs make it pretty clear that 32 bits is too small.

     Brian