[Dnsmasq-discuss] Difference between SLAAC and RA-ONLY mode

Shixiong Shang sparkofwisdom.cloud at gmail.com
Wed Dec 18 15:21:09 GMT 2013


Hi, Simon:

This is very helpful! Thanks a lot for your confirmation! 

A quick question, is there any way we can set M-bit to 1 and set A-bit to 0? In other words, I am trying to force VM to use DHCPv6 only, but not SLAAC?

Thanks again!

Shixiong






> On Dec 17, 2013, at 1:08 PM, Simon Kelley <simon at thekelleys.org.uk> wrote:
> 
>> On 17/12/13 17:34, Shixiong Shang wrote:
>> Hi, Simon:
>> 
>> Thanks a lot for your quick clarification! Just want to make sure I
>> clearly understand what you mean….if the dhcp-range contains a range
>> of IPv6 address, then slaac should enable dhcpv6 + ra; if the
>> dhcp-range contains the single IPv6 address, then slack will only do
>> ra, but not dhcpv6…..Same as ra-only. In other words, how
>> slaac/ra-only set MOAL bits depends on dhcp-range…..Is my
>> understanding correct?
> 
> That's correct.
> 
> 
> Simon.
> 
>> 
>> Shixiong
>> 
>> 
>> 
>> On Dec 17, 2013, at 11:55 AM, Simon Kelley<simon at thekelleys.org.uk>
>> wrote:
>> 
>>>> On 17/12/13 12:29, Shixiong Shang wrote:
>>>> Hi, guys:
>>>> 
>>>> I tried both “slaac” mode and “ra-only” modes with dnsmasq
>>>> version 2.66. One thing I noticed was, both modes set the same
>>>> bit value in the RA:
>>>> 
>>>> M-bit = 0, O-bit = 0, A-bit = 1, L-bit = 1.
>>>> 
>>>> I am wondering what’s the difference between these two modes
>>>> then? Would you please shed some light on it?
>>> 
>>> There's no difference: "slaac" and "ra-only" have exactly the same
>>> effect. Reading back the manpage, the description is very confusing
>>> and should be re-written.
>>> 
>>> The reason for having two different keywords is that they can be
>>> used with and without DHCP
>>> 
>>> dhcp-range = 1234::1, 1234::100, slaac
>>> 
>>> will do RA with MOAL bits all set, and provide DHCPv6
>>> 
>>> dhcp-range = 1234::1, slaac
>>> 
>>> will do RA with only AL bits set, and not DHCP. It's maybe clearer
>>> to be able to be able to write.
>>> 
>>> dhcp-range = 1234::1, ra-only
>>> 
>>> in this case.
>>> 
>>> Cheers,
>>> 
>>> Simon.
>>> 
>>> 
>>> 
>>> 
>>>> 
>>>> Thanks!
>>>> 
>>>> Shixiong _______________________________________________
>>>> Dnsmasq-discuss mailing list
>>>> Dnsmasq-discuss at lists.thekelleys.org.uk
>>>> http://lists.thekelleys.org.uk/mailman/listinfo/dnsmasq-discuss
>>> 
>>> 
>>> _______________________________________________ Dnsmasq-discuss
>>> mailing list Dnsmasq-discuss at lists.thekelleys.org.uk
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> 



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