On Sun, 2012-07-29 at 11:11 -0500, Bruce Dubbs wrote: > Bryan Kadzban wrote: > > Bruce Dubbs wrote: > >> What I'm using right now is: > >> > >> # Ignore Xen virtual interfaces > >> if [ -e /proc/xen ]; then > >> msg="The rules file should not be created in the Xen environment" > >> usage > >> fi > >> > >> I'm not sure if that is right or not. Someone with Xen needs to verify. > > > > Hmm, I don't know much about how Xen actually works for network devices, > > but I can see two ways to do it in general. > > > > First, it could provide exclusively virtual NICs, with effectively > > random MAC addresses at each boot. (Like qemu does AFAIK.) It would use > > tun/tap or something like that to get out to the real network. But > > second, it could provide access to the host's NIC directly to the VM, > > intercepting the actual hardware MMIO operations and watching to make > > sure the VM<->VM isolation is maintained. > > > > If it does only the first, then your method seems like it should work -- > > if Xen is running at all, then refuse to write a rules file. But if it > > ever does the second, then the script will have to filter out interface > > by interface, which ones are OK and which ones are not. > > > > The latter (filtering by interface) is what the current rules do, but of > > course that doesn't mean that's the only way to successfully do it. > > > > Anyone run Xen? Should we just try it and see what happens? :-) > > It doesn't seem very likely to me that any virtual system would have > more than one virtual NIC. What would be the purpose?
I've seen plenty of virtual systems with multiple virtual NICs. This is quite often seen in enterprise environments where non-production systems use virtualisation to minimise hardware spend, in order to support production systems that are deployed on real tin. The layer 3 network design is usually kept consistent between production and non-production environments in order to rule out differences between them causing any behavioural differences. Therefore, if you can imagine a production system requiring management, application and backup VLANs, for example, the non-production VM would have to have 3 virtual NICs. Regards, Matt. -- http://linuxfromscratch.org/mailman/listinfo/lfs-dev FAQ: http://www.linuxfromscratch.org/faq/ Unsubscribe: See the above information page
