[Dnsmasq-discuss] No IPv6 router advertisements for subnets other than /64?

[Simon Kelley]

On 16/09/13 11:16, Roy Marples wrote:
> On 16/09/2013 10:44, Simon Kelley wrote:
>> SLAAC works by generating addresses by composing the prefix and the
>> so-called Interface Identifier.
>>
>> RFC-4291 says: "For all unicast addresses, except those that start
>> with the binary value 000, Interface IDs are required to be 64 bits
>> long and to be constructed in Modified EUI-64 format."
>>
>> and RFC-4862 says: "If the sum of the prefix length and interface
>> identifier length does not equal 128 bits, the Prefix Information
>> option MUST be ignored."
>>
>> from which I deduce that the prefix length MUST be 64 when using SLAAC.
>
> An advertised prefix does not mandate the use of SLAAC.
>
> See a related discussion about DHCPv6 and prefix length here:
> https://lists.isc.org/pipermail/dhcp-hackers/2013-September/002019.html
>
> That has links elsewhere to use case's where the prefix is most
> definitely not /64.
>

That links seems to refer entirely to DHCPv6. Dnsmasq will allow non-64 
prefix lengths for DHCPv6. What we're talking about here is rfc4861 
router advertisements and I'm not sure how the discussion you reference 
applies there.

Cheers,

Simon.