Re: Multiple NICs with Monolithic kernel

[Kevin Buhr <buhr@telus.net>]

Michael West <quagly@mitzit.net> writes:
> 
>      The final thing which I still do not understand is that, after I
>      passed the ether= kernel parameters for each card, only eth0 would
>      work.  But if I `ifdown eth0` then only eth1 would work.  Finally
>      if I `ifdown eth1` then eth2 would work.  This one has got me
>      stumped.  

I'm pretty sure that has nothing to do with the "ether=" kernel
parameter.  It would work the same either way.

It's just the way Linux does business: if you run "tcpdump -i eth1" on
the Linux machine, you'll probably see it accepting packets on eth1.
However, there's nothing forcing it to *reply* to, say, a ping on the
same interface the original packet came in on.  With "eth1" connected,
packets are coming in on that interface but trying to go out on the
disconnected "eth0".  You have to bring "eth0" down before they go out
on "eth1" instead.  Then, you have to bring "eth1" down before they go
out on "eth2" instead.

There are ways to force interface affinity, in the sense that a packet
whose source address is 10.0.1.11 can be forced to route out on eth1,
but that requires something like rule-based routing.

-- 
Kevin <buh@telus.net>