On 01/02/12 21:06, Les Mikesell wrote: >> Hmm... >> >> I just tried this and besides needing ip route "add" default >> >> It does not seem to work when I unplug the cable on my primary link. Well, I should disclose that is an experiment, and I may not have explained the config fully - see the pages I referenced for more authoritative information. I did think I had it working but I am less sure now, and caching looks like it may be a problem. I should emphasise that the main question I have here is: is RHEL's scheme for configuring routing flexible enough to accommodate such configurations? And if it isn't, is there anything I should bear in mind when hacking a script to do this sort of thing, in order to avoid breaking my system or generally fighting against the system's assumptions? > I don't think CentOS is smart enough to automatically drop routes > associated with a NIC that is down like a Cisco would. If you put > routes in /etc/sysconfig/network-scripts/routes-eth? to match the > device names, the ifup and ifdown scripts will add/remove routes when > you manually run time to enable/disable a particular NIC, Right; and then one NIC's state controls the routing configuration for both. I can't see an easy way around that. > but that doesn't get you automatic failover. > And with ethernet type devices it > is pretty rare for the link to go away at the same time the packets > stop getting through anyway. Just to clarify, by "that" do you mean custom "routes in [..]/routes-eth?" or the nexthop configuration I mentioned? It'd guess the former, but I'm more interested in the latter. Based on some tests I suspect it works initially, then if things change, the routing cache will keep the old non-working config until someone flushes it. Note, I'm not sure about this either (due to the general fog of fatigue), and I'm thinking I should try a an entirely different approach. Thanks, N