[Dnsmasq-discuss] Using IPv6 DHCP

Simon Kelley simon at thekelleys.org.uk
Wed Oct 3 14:34:08 BST 2012


On 03/10/12 13:45, Sean Boran wrote:
>> I was initially surprised: it works just like you would like it to.
>>
>> Now, this works with radvd and dnsmasq.  The question is whether dnsmasq
>> could do the same thing for RA while continuing to do the dhcpd/dhcpd6 and
>> dynamic dns stuff so that it was unnecessary to run radvd.  This works on an
>> IPv6-only network.
> 
> Now that only works with your patch to fedora?
> 
> 
> Using radv as you described (AdvSendAdvert on; AdvManagedFlag on;),
> instead of dnsmasq
> 
> - On Ubuntu 12.04, network=automatic, SLAAC (but not DHCP) addresses
> are assigned, default route works.
> - with Automatic/DHCP, a dhcp address is assigned, but no route :-(
> - with Automatic/Address only, SLAC+dhcp address is assigned, route works.
> 
> On a windows 7 client, only a slaac address is assigned, route is fine.
> You indicated being able to get windows 7 to work as desired?
> 
> 
> Finally, disable radvd and in dnsmasq "enable-ra" agin.
> The Ubunut client with "with Automatic/Address only", gets only SLAAC,
> not DHCP.
> In the discussion so far, was it indicated if dnsmasq RA ca do the
> equivalent of "AdvSendAdvert on; AdvManagedFlag on;" ?
> 
> 

There's a third dimension, which is the "A" flag in advertised prefixes,
which is what tells clients if they are allowed to use SLAAC addresses.


There are six different relevant dhcp-range declarations, a simple
dhcp-range with IPv6 addresses, the same, but with ra-only, the same
with ra_stateless, a subnet with ra-only, a subnet with ra-names, and s
subnet with ra-stateless. Here is the matrix of what gets set/provided
where.

                     M-bit   O-bit   A-bit  stateless-DHCP DHCP-address
range                  x        x                  x             x
range+ra_only          x        x       x          x             x
range+ra_stateless              x       x          x             x
ra-only                                 x
ra-names                                x
ra-stateless                            x          x

The first line assumes that enable-ra is set, otherwise dnsmasq never
sends any router advertisements.

> In the discussion so far, was it indicated if dnsmasq RA ca do the
> equivalent of "AdvSendAdvert on; AdvManagedFlag on;" ?
>

enable-ra and a dhcp-range will do that.

Cheers,

Simon.
















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