On Mon, 11 Sep 2000, Andi Kleen wrote: > On Mon, Sep 11, 2000 at 02:31:55PM -0400, Edwin Chiu wrote: > > Hi, > > > > If I have multiple default gateways, and I'm using iproute2 for routing, > > how can I define fallback default gateways? > > > > i.e. if gateway 192.168.0.1 dies or goes down, how do I make traffic go > > through 192.168.0.10? > > You don't need to do anything, just define multiple default routes. How is this going to work? How will the kernel know which of the default gateways is currently up? Usually packets to down gateways just vanish unnoticed. Any timeouts from the TCP/IP application go back to the originator, the linux *router* would have problems to realize they belong to a packet it routed some seconds ago (provided it actually is a hop on the back route which cannot be guaranteed). I'd really like to know how this is implemented (pointers/url to readme, docs.. ), it would be a great feature. However, I doubt this will work. I can imagine that the kernel routes default packets to the gateways in a round robin fashion. This way, if one of three default gateway fails, a third of the packets is lost but network connectivity is still there (at least to some extent). Not a really clean solution though, IMHO. I'd assume you need some kind of routing process/daemon that checks availability of the gateways (by ping or some other routing info exchange) and adjusts the routing tables accordingly. Theoretically this process could be embedded into the kernel, but I don't see a real advantage about a user process here. Please enlight me, THX, Michael. -- Michael Weller: eowmob@exp-math.uni-essen.de, eowmob@ms.exp-math.uni-essen.de, or even mat42b@spi.power.uni-essen.de. If you encounter an eowmob account on any machine in the net, it's very likely it's me. - : send the line "unsubscribe linux-net" in the body of a message to majordomo@vger.kernel.org
