On 16/07/13 09:38, Uwe Schindler wrote:
Hi,
I really like the dnsmasq implementation as replacement to my
previous installation with radvd, because it closely integrates with
DHCP. It also sends instant RA when a client requests DHCP, so it
does not have to wait until the RA is sent out automatically.
But I found a problem, especially happening with mobile phones
(Android, Galaxy S3 in my case). When those go into sleep mode, they
no longer listen to router advertisements, so after waking up, their
address was already deprecated by the network stack and they have to
wait for a new RA coming in. Unfortunately this happens too seldom
(RA_INTERVAL is 600, means 10 minutes). They don't send any DHCP
requests anymore, because the IPv4 DHCP lease is still fine (I have a
lease time of 24 hrs for IPv4 leases, but 20 minutes for IPv6
lifetime - because those are not really static - see below).
Would it be possible to make the RA_INTERVAL configureable so I can
send RAs in a periodic manner like with radvd? I would like to send
RAs every 3 or 10 seconds like I had with radvd configured. This is
not possible without patching dnsmasq.
That's certainly a straightforward thing to do.
A second thing related to RAs: I am living in Germany, where the
assigned prefix to local networks is not really static (for privacy
reasons), so it changes quite often (every 24hrs, enforced by DHCP
prefix delegation on the PPPoE interface). When the prefix changes,
dnsmasq should send (like radvd is doing) a zero lease time RA for
the old prefix. I found out that dnsmasq.conf can set "deprecated" as
life-time in the dhcp-range, but that would make all RAs going out
have a time of 0s. It would be good if dnsmasq would send "active"
prefixes with the given non-zero lifetime, but once a prefix
disappears from the network adaptor, send extra RAs do deprecate the
old prefix (using the old prefix with time=0) for a number of times.
RA's are not the same as DHCP, there's no such thing as a "lease time".
What there is, is preferred and valid lifetimes. What should happen is
that when old address is about to go away, the address for that prefix
on the network adaptor should have its preferred lifetime set to zero,
and dnsmasq will then notice that and send RA's with the preferred
lifetime also set to zero.
You can see the lifetimes in the output of "ip addr show"
inet6 2a01:348:29f::100/64 scope global
valid_lft forever preferred_lft forever
^^^^^^^^^ ^^^^^^^^^^^^^
Cheers,
Simon.
Uwe
----- Uwe Schindler H.-H.-Meier-Allee 63, D-28213 Bremen
http://www.thetaphi.de eMail: u...@thetaphi.de
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