[Dnsmasq-discuss] dnsmasq and RA

[Simon Kelley]

On 01/11/12 12:59, Gene Czarcinski wrote:
> On 10/31/2012 04:41 PM, Gene Czarcinski wrote:
>> Instead of running both radvd and dnsmasq, I would like to run only
>> dnsmasq and have it do what is now being done by radvd.
>>
>> This is for libvirt so there are some specifics which could help.
>>
>> 1. There will be one and only one interface for an instance of dnsmasq.
>>
>> 2. Currently (at least with some patches I have created) run one ipv4
>> dhcp subnetwork or one ipv6 dhcp supnetwork or both one ipv4 network
>> and one ipv6 network.
>>
>> 3.  If a dhcp-range is specified for the ipv6 subnetwork then I need
>> the AdvManagedFlag on which (I believe) is done with the additional
>> dsnmasq parameter "enable-ra".
>>
>> 4.  But, I may have an IPv6 subnetwork but dhcp-range has not been
>> specified.  In this case I want the AdvManagedFlag off.  This one is
>> the situation that I am not clear on.
>>
>> 5.  None of the other dnsmasq capabilities with respect to RA will be
>> used.
>>
>> Comments/suggestions?
>>
>> If this requires a little enhancement patch, I am willing.
>>
>>
> OK, I believe I have answered my own question but I would still like
> confirmation.
> 
> I ran a test with no radvd running ... only dnsmasq.  With enable-ra and
> dhcp-range specified for ipv6 addresses, the client side gets a dhcp6
> address and RA default route.
Check.

>  With enable-ra and NO dhcp-range
> specified, the client gets a SLAAC address and RA default route.

That's not what I'd expect. To get RA on a subnet but not dhcp, you need
to have

dhcp-range=<subnet>,ra-only

enable-ra is superfluous in that case.
> 
> With enable-ra and dhcp-range,I do notice a lot of RTR-ADVERT messages
> ... like one every couple of seconds.  Is there a way to suppress this
> message and/or increase the time between the events or at least the
> messages [that is without disabling dhcp logging] ?

The frequency will decrease over time. It's roughly every 10 seconds for
the first minute, and then about every 10 minutes.

Cheers,

Simon.

> 
> Maybe it would be useful is this message was only sent to the syslog
> once every ten or twenty events.
> 
> Gene
> 
> 
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