persistent settings for virbr0-nic

[Elleni]

Being new with centos, I hope this question has not been asked already zillions of times. I did not find an answer asking google, so I thought, maybe its about time to sign in here and say hello

I have so far setup centos 8 as kvm host, and within two guests - one windows and one with centos based nethserver.

Everything works fine so far but I have a question. For NethServer vm being able to act as dhcp server I have disabled dhcp for virbr0 and created an isolated network. That works fine.

I also have activated promiscious for virbr0-nic following this guide.. Now I wonder, if the description for making this change persistent is also correct for a kvm nic as there are only ifcfg-* files for the physical nics of my server. Should I still just create ifcfg-virbr0-nic in /etc/sysconfig/network-scripts/ and add PROMISC=yes there? Or is there another place, where this can be made persistent?

After reboot of the kvm host I realized that the isolated network has disappeared, so another question is why. I can recreate it and put it in promisuous mode with just:

virsh net-create virsh.br-lan.net.xml && ip link set virbr0-nic promisc on

but it would be nice, if those two things could be persistent. Is that possible?