On 08/25/2015 08:17 PM, Spanky Horawitz wrote:
I'm trying to migrate my VirtualBox test lab to KVM.  In my VB configuration, I have several VM routers with 4 interfaces each.  Each router has a bridged interface which connects them all together and to the outside world.  I have servers/clients dispersed on each of the other private (Isolated) segments that use the routers as default gateways.

In trying to make this work, I used Virtual Machine Manager to define 3x Virtual Networks (Isolated networks) and created a VM router which has 3 interfaces (192.168.x.1) on each Isolated network and a 4th interface using the br0 interface to get to the outside world.  The router is able to connect to the outside world.

Using Virtual Machine Manager, I also created "client" VM and connected it's single interface to one of the Isolated networks.  While testing connectivity of the "client" VM to the router, it seems to go straight to the Host (tested using 'ssh 192.168.x.1'.)  I'm trying to isolate the networks from the Host and have the router receive packets for the 192.168.x.1 address on the individual Isolated network segments.

Host:
br0 (em1): 192.168.1.16
vibr0 (default): 192.168.122.1
virbr1: 192.168.2.1
virbr2: 192.168.3.1
virbr3: 192.168.4.1

VM router:
eth0: 192.168.1.10
eth1: 192.168.2.1
eth2: 192.168.3.1
eth3: 192.168.4.1

VM client:
eth0: 192.168.3.101


Is there some trick to isolate the Host from the VM's?

"Isolated" means "connection only to the host and to the guests on this network". If you want the guests to be isolated from the host, then you need to define a virtual network with no IP address at all for the host, then run a DHCP server on the guest that is acting as the router.


  Is there a comprehensive guide that explains how the networks should be setup (with/without Virtual Machine Manager)?

Several years ago someone started writing such a guide, but then switched to another job before it was finished. There is a lot of information on the libvirt wiki, but not necessarily well organized or formatted:


   http://wiki.libvirt.org/page/Networking