Re: [Qemu-devel] Re: [PATCH-updated] qemu/net: add raw backend

[Jamie Lokier <jamie@shareable.org>]

Michael S. Tsirkin wrote:
> > The fact that network manager does work well with bridged interfaces is  
> > a network manager bug.
> 
> Network manager was just one example.

Even if network manager and all other configuration programs are fixed
to handle a bridge, it's still quite fiddly to configure them.

I find I have to use

   - bridges to an uplink interface for some VMs (guest has IP on same
     network as host, fixed host interfaces, typically in servers)

   - bridges attached to changing uplink for some VMs (laptop, where
     the main internet uplink changes between eth0/wlan0/ppp0/bnep0
     according to available signals)

   - no bridge at all (just routing tap, used on all sorts of machines)
     for VMs needing to run on host-local IPs and talk to the host,
     and maybe NAT to the internet

   - bridges not attached to any host interface, just multiple tap
     interfaces, used to connect guests with host-local IPs that must
     see each other's broadcasts

The corresponding iptables is rather tricky too.

> > It's getting fixed so in the near future, tap will satisfy all of
> > these requirements.

That will be really nice if it does.

-- Jamie