Re: [Qemu-devel] Networking possibilities

[Tim]

> I would like to know if it is possible to run a few instances
> of Qemu's ( ie a few guest OS'es ) and make them network 
> with one another ? In each of the instance there maybe 
> multiple network cards, I would like to be able to specify each 
> network card to go to which tun device and then allow another 
> instance to connect specifically to that particular tun device,
> instead of only connected to the host OS.
> 
> That's tun/tap devices are used to connect multiple instances
> of qemu together or with the host OS.
> 
> Bottomline I would like to be able to set up a farm of guest OS's
> which could perform internetworking among each other. This is
> extremely useful for testing/developing networking software. 
> Is it possible ?


One possible way to do this would be to spawn all of your Qemu
instances, each with their own TUN interface, then bridge the TUN
interfaces together on the (linux) host.  Linux bridging code comes
standard with 2.6 kernels now (i believe), and I have used it before to
bridge a Qemu TUN interface with a physical interface in the host
before.  I haven't tried putting together multiple TUN interfaces before
though. 

There are several references online for how to do Linux bridging.  If
you can't find them through google, I can dig up a link.

HTH,
tim