Re: [Qemu-devel] Qemu-KVM VETH

[Tim Epkes]

Agree in all points.  Thanks for the information.  I'll give the patch a try.

Tim

Sent from my iPhone

On Sep 20, 2013, at 1:26 PM, Stefan Hajnoczi <address@hidden> wrote:

> On Fri, Sep 20, 2013 at 11:48:50AM -0400, Tim Epkes wrote:
>> The problem aI face is that a bridge in the middle ( using taps) breaks
>> LLDP ( L2 discovery protocol) and should break ISIS as well.  Sockets
>> aren't bad, but if for some reason I take the listener VM down and bring
>> back up, then I have to bring down all connector VMs, which chains on
>> itself if there is a lot of connectivity defined.  When UDP was available
>> that wasn't an issue.
> 
> I just checked linux.git but this patch has not been applied (although
> it's trivial if you're willing to rebuild your kernel from source):
> http://comments.gmane.org/gmane.linux.network/208908
> 
> It sounds like improving net/socket.c might be the right place to look.
> 
>> Anyway, that is how I came to VETHs.  I am aware that you can use UDP
>> multicast, but performance past one hop is extremely poor ( resulting in 3
>> of 5 pings to be lost.  Thanks
> 
> Unfortunately the veth driver does not hand Ethernet frames to/from
> userspace.  We really need something tap-like where userspace can
> inject/extract packets.
> 
> Stefan