[Dnsmasq-discuss] Confusion about "no address range available for DHCPv6 request via ..."

[Petr Menšík]

Are you aware that 80 on the end of dhcp-range is lease time, not any 
prefix size? Consider using of constructor:tapvm4qyj3a instead of manual 
end address. If I see correctly the end address is the same as the start 
address. Not sure how this should behave, but I would not be surprised 
if it did not work.

Try this:

dhcp-range=2a01:4f9:2b:35a:7df2::2,constructor:tapvm4qyj3a,80

On 18. 04. 23 10:40, Daniel Farina wrote:
> Hello everyone,
>
> I have been trying to set up an IPv6-only network for a virtual 
> machine with route advertisements and DHCP configuration. I've had 
> some success, but I have a question.
>
> I have a dnsmasq.conf that looks like this, to delegate a /80 chunk of 
> a /64 network to a virtual machine:
>
> interface=tapvm4qyj3a
> enable-ra
> dhcp-authoritative
> leasefile-ro
> ra-param=tapvm4qyj3a,mtu:1280,high,60,1200
> dhcp-range=2a01:4f9:2b:35a:7df2::2,2a01:4f9:2b:35a:7df2::2,80
>
> If I have an address configuration like this on the host outside the 
> virtual machine, it works well:
>
> 3: tapvm4qyj3a: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc 
> fq_codel state UP group default qlen 1000
>     link/ether 82:d6:93:69:72:82 brd ff:ff:ff:ff:ff:ff
>     inet6 2a01:4f9:2b:35a:7df2::1/80 scope global
>        valid_lft forever preferred_lft forever
>     inet6 fe80::80d6:93ff:fe69:7282/64 scope link
>        valid_lft forever preferred_lft forever
>
> The thing I find dissatisfying about this is that the VM is not able 
> to listen on 2a01:4f9:2b:35a:7df2::1 anymore once I've done this, is 
> my understanding: the host will process the traffic, right? If I 
> remove the address on the guest's network, dnsmasq warns me 
> repeatedly, and does not work:
>
> ip addr del 2a01:4f9:2b:35a:7df2::1/80  dev tapvm4qyj3a
>
> dnsmasq-dhcp: no address range available for DHCPv6 request via 
> tapvm4qyj3a
> dnsmasq-dhcp: no address range available for DHCPv6 request via 
> tapvm4qyj3a
> dnsmasq-dhcp: no address range available for DHCPv6 request via 
> tapvm4qyj3a
> ...
>
> My question is partially that of norms: is it normal to squat on a bit 
> of the guest's address space like this? Is there a preferred way that 
> avoids this, or does something different still? I know that a number 
> of non-SLAAC configurations tend to sit on ::2 as the first unicast 
> address, is this related to the reason why?
>
> I will be expanding my use of dnsmasq to DNS, so this may figure in 
> the answer.
>
> Thank you for considering my question.
>
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-- 
Petr Menšík
Software Engineer, RHEL
Red Hat, http://www.redhat.com/
PGP: DFCF908DB7C87E8E529925BC4931CA5B6C9FC5CB