[TriLUG] Networking and Fedora

[Justis Peters]

Jeff Schornick wrote:
> Preparing to make a fool of myself...
>   
>> 10.2.2.0        0.0.0.0         255.255.255.0   U     0      0        0 eth0
>> 10.2.2.0        0.0.0.0         255.255.255.0   U     0      0        0 br0
>>     
> You appear to have two routes to the same destination subnet, equal
> metric to two different interfaces.  Since eth0 and br0 aren't
> currently bridged, I'd imagine this would lead to rather inconstant
> delivery.  I'm honestly not sure how the kernel choses which route to
> use under these circumstances, but I'm 99% sure it won't deliver each
> packet to both.
>
> Do you perhaps want eth0 part of the br0 bridge group?
>   
Didn't see your reply before I sent mine. I think you've got it nailed,
Jeff. I hadn't noticed that eth0 is not yet attached to br0.

The way that Xen users frequently do this is to rename the "real" eth0
to peth0 and then name the bridge itself eth0. You would then add peth0
to the bridge, along with all the virtual interfaces for the guest VMs.
Some people find this confusing; others like it.

Joseph: The quick way to test our theory would be to remove the second
route and then add eth0 to the br0 bridge. The commands should look
something like this:
  route del -net 10.2.2.0/24 br0
  brctl addif br0 eth0

I'm not sure of the preferred way to make those changes persistent in
Fedora, but I'm sure the answer is online and easy to find. Also note
that you probably want to run them in the order listed above. I suspect
that reversing the order might create a feedback loop between the
routing table and the bridge.

Best of luck and let us know how it goes.

Kind regards,
Justis