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

Uwe Schindler uwe at thetaphi.de
Wed Jul 24 19:16:56 BST 2013


Hi,

> 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.

I meant the life time, it was just a typo somehow :-) The idea here was to send preferred_lifetime=0 in RAs for prefixes that disappeared from the interface to "inform" the clients that they are no longer useable (my provider does not route old prefixes after a reconnect with PPP). Currently you have to set the lifetime very low (which produces more traffic on the wire) or manually delete or switch on/off the network adaptors once the router reconnects or the prefix changes for some reason.

My proposal is to keep a list of "previous prefixes" from the constructor:ethX code and also send those prefixes, but with lifetime=0 to inform all client to no longer use that address. Those 0-lifetime RAs should be sent at least for the length of the original lifetime. Radvd has code to handle this (although it’s a bit buggy).

Uwe




More information about the Dnsmasq-discuss mailing list