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

[Simon Kelley]

On 16/09/13 11:49, Roy Marples wrote:
> On 16/09/2013 11:44, Simon Kelley wrote:
>> 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.
>
> It shows a case where a RA prefix is (from memory) /112 and the address
> is assigned by DHCPv6 and not SLAAC.
> DHCPv6 has no prefix notion (thus each address would be /128).
>

OK, got it. That lead me to RFC 5942, which is also very relevant.

So it looks like, when doing DHCP_and_RA on a subnet, the prefix length 
can indeed be something other than 64.

That's allowed by dnsmasq, if you configure a subnet for DHCPv6 and use 
--enable-ra to get the prefix advertised as well, then prefix length can 
be greater than 64.

Cheers,

Simon.