Hello, CentOS8, oVirt 4.4.1.10-1.el8 I am trying to setup active-backup (mode=1) bonding mode with custom properties. I have one 10GE switch, the second is just 1G. 10GE link is the primary one. cat /etc/sysconfig/network-scripts/ifcfg-bond0 BONDING_OPTS="active_slave=ens5 downdelay=0 miimon=100 mode=active-backup primary=ens5 updelay=0" TYPE=Bond BONDING_MASTER=yes PROXY_METHOD=none BROWSER_ONLY=no IPV4_FAILURE_FATAL=no IPV6_DISABLED=yes IPV6INIT=no NAME=bond0 UUID=c054364e-47cf-47ee-a7fc-70b37c9977e7 DEVICE=bond0 ONBOOT=yes MTU=9000 When I try to add a custom parameter "fail_over_mac=active" (which I believe could solve my problems with stalled mac addresses in switch's cam table in case of failover) I got... "Error while executing action HostSetupNetworks: Unexpected exception" ...in manager. In the engine.log it looks like 2020-07-22 21:20:35,774+02 WARN [org.ovirt.engine.core.vdsbroker.vdsbroker.HostSetupNetworksVDSCommand] (default task-8) [da1984f3-f38b-4e0a-ac80-a81e67d73ff0] Unexpected return value: Status [code=-32603, message=Internal JSON-RPC error: {'reason': 'MAC address cannot be specified in bond interface along with specified bond options'}] 2020-07-22 21:20:35,774+02 ERROR [org.ovirt.engine.core.vdsbroker.vdsbroker.HostSetupNetworksVDSCommand] (default task-8) [da1984f3-f38b-4e0a-ac80-a81e67d73ff0] Failed in 'HostSetupNetworksVDS' method 2020-07-22 21:20:35,774+02 WARN [org.ovirt.engine.core.vdsbroker.vdsbroker.HostSetupNetworksVDSCommand] (default task-8) [da1984f3-f38b-4e0a-ac80-a81e67d73ff0] Unexpected return value: Status [code=-32603, message=Internal JSON-RPC error: {'reason': 'MAC address cannot be specified in bond interface along with specified bond options'}] 2020-07-22 21:20:35,811+02 ERROR [org.ovirt.engine.core.dal.dbbroker.auditloghandling.AuditLogDirector] (default task-8) [da1984f3-f38b-4e0a-ac80-a81e67d73ff0] EVENT_ID: VDS_BROKER_COMMAND_FAILURE(10,802), VDSM ovirt-hci01.mch.local command HostSetupNetworksVDS failed: Internal JSON-RPC error: {'reason': 'MAC address cannot be specified in bond interface along with specified bond options'} Could anybody explain me what 'MAC address cannot be specified in bond interface along with specified bond options' means? I believe a MAC address is not configured in interface configuration. Or does it mean 'fail_over_mac=active' is not supported in oVirt? Thanks in advance, Jiri