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

Shixiong Shang sparkofwisdom.cloud at gmail.com
Thu Dec 19 11:53:41 GMT 2013


I am using version 2.66.



> On Dec 19, 2013, at 5:31 AM, Simon Kelley <simon at thekelleys.org.uk> wrote:
> 
>> On 19/12/13 04:02, Shixiong Shang wrote:
>> I just found a workaround….If I replaced “slaac” mode with “static” mode, then it just worked fine…But I don’t understand why it worked. :(
> 
> What version of dnsmasq are you using? That command line doesn't generate an error with the latest code.
> 
> 
> Cheers,
> 
> Simon.
> 
>> 
>>> On Dec 18, 2013, at 1:15 PM, Shixiong Shang<sparkofwisdom.cloud at gmail.com>  wrote:
>>> 
>>> Hi, Simon:
>>> 
>>> I put the range inside —dhcp-range filed as shown below to enable DHCPv6 mode. When I issued the command, the dnsmasq didn’t return any error. However, it failed to launch and the syslog threw errors. I am wondering which the “bad dhcp-range” refer to?
>>> 
>>> sudo dnsmasq --no-hosts --no-resolv --strict-order --bind-interfaces --except-interface=lo --leasefile-ro --enable-ra --port=547 --dhcp-range=set:tag1,2001:db8:2::2,2001:db8:2:0:ffff:ffff:ffff:fffe,slaac --dhcp-hostsfile=/var/lib/app/dhcp/b3051625-e7de-4500-99d9-e9e80f5a8349/ipv6host --dhcp-option=tag:tag1,option6:dns-server,[2001:4860:4860::8888] --pid-file=/var/lib/app/dhcp/b3051625-e7de-4500-99d9-e9e80f5a8349/ipv6pid
>>> 
>>> Dec 18 10:10:14 net-network2 dnsmasq[19722]: bad command line options: bad dhcp-range
>>> Dec 18 10:10:14 net-network2 dnsmasq[19722]: FAILED to start up
>>> 
>>> Thanks!
>>> 
>>> 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
>>>>>> http://lists.thekelleys.org.uk/mailman/listinfo/dnsmasq-discuss
> 



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