[Dnsmasq-discuss] Make RA_INTERVAL configureable? Deprecate old prefixes?

[Uwe Schindler]

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.

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.

Uwe

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Uwe Schindler
H.-H.-Meier-Allee 63, D-28213 Bremen
http://www.thetaphi.de
eMail: uwe at thetaphi.de