Jacked network bridges

Tod Hansmann plug.org at todandlorna.com
Sat Jan 28 23:03:27 MST 2012

On 1/28/2012 3:12 PM, Gabriel Gunderson wrote:
> This is what I know:
> * Network B is jacked :)
> * The problem is at layer 2. I know this because I can't arping from
> set Y to set X even though they are tied to the same bridge.
> * There are no duplicate MAC addresses.
> * The whole process of building this setup is fully automated (via
> fabric) and can easily be recreated, so it not a human error; it's
> more like a misconfiguration (but why set X and not set Y?). Hosts in
> set X and Y are all created with the same build process.
> * The only thing that's different about them (and I think this *must*
> be key) is that set X also has the 3rd interface to the C network.
> But, that shouldn't have anything to do with network B not working :/
> * I need more sleep.
I'm guessing this has to do with VLAN tagging, and I'm not entirely sure 
how all that works in virtual hosts let alone kvm/libvirt which I've 
never used thus far.  The VLAN tagging could be working on Set X 
specifically because it has the 3rd interface.  I don't know what that 
3rd interface translates into on the wire, and on which of the 3 host's 
wires, but it's probably more telling than you're giving it credit for.

Sorry I don't have more specific ideas on this.  I'm kind of hoping a 
sounding board effect will be beneficial for you here, as your situation 
is very specific.  Call me if you want to keep bouncing ideas back and 

-Tod Hansmann

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