[Dnsmasq-discuss] Cannot assign IPv6 address for /96 subnet

Simon Kelley simon at thekelleys.org.uk
Wed Feb 20 10:58:56 GMT 2013


On 20/02/13 02:16, Sheng Yang wrote:
> Hi Simon,
> 
> Did you use dhcphost option? dhcp-range works for me(if I specify a
> range), but not with dhcp-host option(when I specify dhcp-range as
> static).

Ah, no, I didn't. I should have read back through the thread. I'll check
again, but it rather looks like this is non possible, by design,  (or
miss-design)

Simon.

> 
> --Sheng
> 
> On Tue, Feb 19, 2013 at 1:06 PM, Simon Kelley <simon at thekelleys.org.uk> wrote:
>> So, I did some testing. I configured an server interface with prefix-length
>> 96, and configured dnsmasq with a dhcp-range and 96 prefix.
>>
>> Using dhclient, I got a lease successfully.
>>
>> The only problem is that dhclient configured the client's interface with
>> prefix-length 64.
>>
>> I moment's thought shows that this is expected: there is nowhere in the
>> DHCPv6 messages for the prefix-length information to be passed to the
>> client. There _is_ a prefix-length field in router-advertisements. but
>> AFAIK, there's no way for the DHCPv6 client to use that information.
>>
>> Of course if you're using RA for address-allocation, using SLAAC, the prefix
>> length has to be 64 anyway.
>>
>> If anyone knows better, or can explain how the standard(s) are supposed to
>> work, please enlighten me.
>>
>> Simon.
> 




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