Failed to start default nework in KVM

Issue

• I have RHEL7 host (it is OSP6 controler)
• For development purposed I wanted to use it simultaneously as KVM host as I do on RHEL6 servers.
• On working RHEL6 I have:

# virsh net-list
Name                 State      Autostart     Persistent
--------------------------------------------------
default              active     yes           yes

# brctl show
bridge name     bridge id               STP enabled     interfaces
virbr0          8000.525400048221       yes             virbr0-nic
                                                        vnet3
                                                        vnet4
                                                        vnet5
                                                        vnet6

• On RHEL7 the default network is missing

# virsh net-list
 Name                 State      Autostart     Persistent
----------------------------------------------------------

# virsh net-start default
error: failed to get network 'default'
error: Network not found: no network with matching name 'default'

• There is no even libvirt.log on RHEL7.
• My goal was to be able to start VM under KVM and be able to use 192.168.122.1 interface to have internet access from them using NAT forwarding (aka "virtual networks„) provided by KVM.