Greetings Laine, > Sent: Wednesday, May 02, 2018 at 8:09 PM > From: "Laine Stump" <laine@xxxxxxxxxx> > To: libvirt-users@xxxxxxxxxx > Cc: daggs <daggs@xxxxxxx> > Subject: Re: connecting host and guest vm using a dummy nic > > On 05/02/2018 12:05 PM, daggs wrote: > > Greetings Laine, > > > >> Sent: Wednesday, May 02, 2018 at 5:56 PM > >> From: "Laine Stump" <laine@xxxxxxxxxx> > >> To: libvirt-users@xxxxxxxxxx > >> Cc: daggs <daggs@xxxxxxx> > >> Subject: Re: connecting host and guest vm using a dummy nic > >> > >> On 05/01/2018 12:12 PM, daggs wrote: > >>> > >>> I want to see if I understood you correctly, I add: > >>> <interface type='ethernet'> > >>> <model type='e1000'/> > >>> </interface> > >>> to the vm's xml, this will result in a new nic in the vm which and in the host which I can use by the host to request dhcp from the router within the vm? > >>> > >> > >> > >> Yes. As long as the emulated device in the guest is listening for DHCP > >> on that interface. > >> > >> Also, note that (as long as your libvirt is at least version 2.1.0) if > >> you don't want to bother doing dhcp on the host and guest, you can > >> assign just a static IP address for the host side of that interface in > >> the libvirt XML like this: > >> > >> > >> <interface type='ethernet'> > >> <source> > >> <ip address='192.168.254.2'/> > >> </source> > >> ... > >> > >> You can even specify routes to be added automatically to the host when > >> that guest is started, e.g.: > >> > >> > >> <interface type='ethernet'> > >> <source> > >> <ip address='192.168.254.2'/> > >> <route family='ipv4' address='0.0.0.0' prefix='0' > >> gateway='192.168.254.1' metric='1'/> > >> </source> > >> ... > >> > >> (this assumes that on the guest side, the OS has configured the emulated > >> ethernet device to have address 192.168.254.1). This can be useful if > >> you want the host to use one path for traffic when the guest isn't > >> running, but switch when the guest *is* running. (In this case, if you > >> can set the default route on the host to have a metric of 2 or higher, > >> then the default route that goes through the guest would be preferred > >> when present). > >> > >> (NB: if you read the documentation for configuring interfaces at > >> https://libvirt.org/formatdomain.html#ipconfig you'll see references on > >> how to configure the IP address of the *guest* in libvirt's xml. Note > >> that this *does not work* for qemu, but only for lxc (and possibly xen, > >> I don't recall right now). This is a limitation of the way that qemu/kvm > >> works (the fact that all guest-side IP info is configured in the guest > >> OS, and libvirt has no reasonable to get to it).) > >> > >> > > > > thanks alot! > > like you've said, I've defined the interface in the xml, booted the device and updated /etc/network/interfaces to alloc dhcp to vnet0. > > that resulted in the proper ip and I can see the router inside the vm. > > BTW, if you'll be running other guests on your host, and may start them > in different orders, you should probably add "<target dev='vmrouter'/> > (or whatever name you like, 15 chars or less and *not* starting with > "vnet") to the <interface> config. IF you do that, you can be assured > that the name of the device on the host will always be consistently > named "vmrouter" (otherwise it just gets the lowest numbered available > "vnetX" device name each time it's started). > I intend to run only one vm on this system, thanks for the tip. > > > > > one thing bothers me, ethtool vnet0 says the speed is 10Mb/s, asking google suggested several solutions. > > I've tried changing the model to virtio but the speed stays the same, the vm router is running kernel 4.4.92, could that be the issue? > > The reported speed should be inconsequential, since there is no wire and > no physical switch involved. It will transfer data as fast as the code > can be executed. > > Also, if virtio works, then *definitely* use that instead of e1000 - the > performance will be much better and overhead much lower. > > so any network test will do? Thanks, Dagg. _______________________________________________ libvirt-users mailing list libvirt-users@xxxxxxxxxx https://www.redhat.com/mailman/listinfo/libvirt-users
