The answer is..
OVN replaced OVS as the networking technology. You cannot switch back to legacy, they
disabled switching between ovs and legacy in the default (1st) datacenter using the gui.
You can however, use Ansible to switch it.
Remove the VDSM ovs setting, it will just mess you up, and it's not supported in 4.2
To able to migrate a VM in 4.2, you have use OVN with OVS.
I did this a few months back, on a 4.2.2 hosted-engine setup:
0) To setup a node in a cluster, make sure the cluster is in OVS, not
legacy.
1) Make sure you have an OVN controller setup somewhere. Default
appears to be the ovirt-hosted-engine.
a) you should also have the external network provider for OVN
configured also; see the web interface.
2) when you install the node, make sure it has openvswitch installed and
running - ie:
a) 'systemctl status openvswitch' says it's up and running. (be sure
it's enable also)
b) 'ovs-vsctl show' has vdsm bridges listed, and possibly a br-int
bridge.
3) if there is no br-int bridge, do 'vdsm-tool ovn-config
ovn-controller-ip host-ip'
4) when you have configured several nodes in the OVN, you should see
them listed as geneve devices in 'ovs-vsctl show', ie:
This is a 4 node cluster, so the other 3 nodes are expected:
[ root at d8-r12-c1-n3 ~]# ovs-vsctl show
42df28ba-ffd6-4e61-b7b2-219576da51ab
Bridge br-int
fail_mode: secure
Port "ovn-27461b-0"
Interface "ovn-27461b-0"
type: geneve
options: {csum="true", key=flow,
remote_ip="192.168.85.91"}
Port "vnet1"
Interface "vnet1"
Port "ovn-a1c08f-0"
Interface "ovn-a1c08f-0"
type: geneve
options: {csum="true", key=flow,
remote_ip="192.168.85.87"}
Port "patch-br-int-to-f7a19c7d-021a-455d-bf3a-c15e212d8831"
Interface
"patch-br-int-to-f7a19c7d-021a-455d-bf3a-c15e212d8831"
type: patch
options:
{peer="patch-f7a19c7d-021a-455d-bf3a-c15e212d8831-to-br-int"}
Port "vnet0"
Interface "vnet0"
Port "patch-br-int-to-7874ba85-8f6f-4e43-9535-5a1b1353a9ec"
Interface
"patch-br-int-to-7874ba85-8f6f-4e43-9535-5a1b1353a9ec"
type: patch
options:
{peer="patch-7874ba85-8f6f-4e43-9535-5a1b1353a9ec-to-br-int"}
Port "ovn-8da92c-0"
Interface "ovn-8da92c-0"
type: geneve
options: {csum="true", key=flow,
remote_ip="192.168.85.95"}
Port br-int
Interface br-int
type: internal
Bridge "vdsmbr_LZmj3uJ1"
Port "vdsmbr_LZmj3uJ1"
Interface "vdsmbr_LZmj3uJ1"
type: internal
Port "net211"
tag: 211
Interface "net211"
type: internal
Port "eno2"
Interface "eno2"
Bridge "vdsmbr_e7rcnufp"
Port "vdsmbr_e7rcnufp"
Interface "vdsmbr_e7rcnufp"
type: internal
Port ipmi
tag: 20
Interface ipmi
type: internal
Port ovirtmgmt
tag: 50
Interface ovirtmgmt
type: internal
Port "patch-f7a19c7d-021a-455d-bf3a-c15e212d8831-to-br-int"
Interface
"patch-f7a19c7d-021a-455d-bf3a-c15e212d8831-to-br-int"
type: patch
options:
{peer="patch-br-int-to-f7a19c7d-021a-455d-bf3a-c15e212d8831"}
Port "eno1"
Interface "eno1"
Port "patch-7874ba85-8f6f-4e43-9535-5a1b1353a9ec-to-br-int"
Interface
"patch-7874ba85-8f6f-4e43-9535-5a1b1353a9ec-to-br-int"
type: patch
options:
{peer="patch-br-int-to-7874ba85-8f6f-4e43-9535-5a1b1353a9ec"}
ovs_version: "2.7.3"
5) Create in the cluster the legacy style bridge networks - ie,
ovirtmgmt, etc. Do this just like you where creating them for the
legacy network. Define the VLAN #, the MTU, etc.
6) Now, create in the network config, the OVN networks - ie,
ovn-ovirtmgmt is on an external provider (select OVN), and make sure
'connect to physical network' is checked, and the correct network from
step 5 is picked. Save this off.
This will connect the two networks together in a bridge, and all
services are visible to both ie dhcp, dns..
7) when you create the VM, select the OVN network interface, not the
legacy bridge interface (this is why I decided to prefix with 'ovn-').
8) Create the vm, start it, migrate, stop, re-start, etc, it all should
work now.
Lots of reading.. lots of interesting stuff found.. finally figured
this out after reading a bunch of bug fixes for the latest RC (released
today)
The only doc link:
https://ovirt.org/develop/release-management/features/network/provider-ph...