I'm working on a load balancer for outbound IP traffic across multiple DSL lines. When one of those lines fail the kernel has to detect this and stop using the line. I applied patches to the kernel to make this work. Can't tell you where I got them, the bloody forum won't let me but look at the loadbalancing section in the Advanced Routing HOWTO and you'll find them.

On my current test site I have the loadbalancer hooked up to the LAN via the Realtek card built into the motherboard (etth0). The DSL lines are on a Winbond NE2000 clone (eth1) and a 3Com card (eth2).
When I pull the cable out of eth1 the kernel detects this and a "NETDEV WATCHDOG: transmission timed out" message appears in the syslog, which is exactly what I want to happen.
However, when I pull the cable out of eth2 I don't get these messages, and the kernel keeps trying to send traffic over the disconnected eth2 interface.

So, how do I get the NETDEV WATCHDOG to bark?

TIA, Rogier

I have a stupid question. I looked at this advanced routing howto: http://tldp.org/HOWTO/Adv-Routing-HO...loadshare.html and I don't see any mention of kernel patching. Are you using an older or newer howto?

I haven't tried load balancing before, but I use the fair queueing system which is pretty much the same thing, just with one ethernet card.

Yeah, it was some other howto, but anyway the patches aren't important, it's just that the bloody kernel doesn't seem to notice me pulling the cable out of eth2.