On Wed, Oct 20, 2004 at 05:37:34PM +0100, Nick Drage wrote: > However if you want to give the routes different metrics.... > > ip route add default via 1.2.3.4 metric 1 > ip route add default via 4.5.6.7 metric 2 > > "ip" will accept that input. > > That should mean if the host can't send the traffic via 1.2.3.4 it will > realise this ( I presume solely if it gets no arp-reply for 1.2.3.4) it > will try and send the traffic via 4.5.6.7 instead. > > That seems to be the way it should work, however on a test box my host > is happily trying to arp for 1.2.3.4 continuosly. > > Anyone help me finish off this answer ;) yes--the linux routing code will do dead gateway detection and fall back to a lower metric route in the event of failure, and also go back to the higher metric route upon resurrection. this can be useful for an active-standby setup. as for which route added by 'route' actually gets used--i've never spent the time to figure out how it picks the one it uses, but it certainly only appears to ever use one--maybe it picks the one with the lowest numerical value... or maybe it uses one of those magic 8-ball things... -j -- Jason Opperisano <opie@xxxxxxxxxxx>
