Score:2

Bridged KVM guest crashes other guests on Ubuntu Desktop 20.04

ph flag

I am new to Ubuntu, but am running Desktop 20.04. I have installed KVM and configured bridged networking per the following two links based on my understanding that the legacy networking service has been replaced by NetworkManager and netplan: Creating an ubuntu kvm networked bridge interface , How to setup bridge networking with kvm on ubuntu.

I am able to bridge my windows guest and it starts and runs with complete local network and internet connectivity. But when I start another windows guest, it crashes the first. And vice versa. Both are configured to use the host-bridge with a static IP.

My /etc/netplan/01-network-manager-all.yaml file contains: enter image description here

And the ip addr output confirms the bridge is working correctly: enter image description here

And networkctl list output is: enter image description here

And brctl list output is: enter image description here

Any help or suggestions would be greatly appreciate. Thank you.

Doug Smythies avatar
gn flag
You haven't specified a renderer in your .yaml file. I have seen other comments that it matters. Your IPs and MACs are different for each windows guest, correct?
matt01 avatar
ph flag
Yes, the IPs and MACs are unique for each guest. And I addded 'renderer: networkd' to the file, and restarted the systemd-networkd service. But the problem still persists.
Doug Smythies avatar
gn flag
Everything looks O.K. to me. As a test, I am running 3 VMs under 20.04, with bridged networking right now. I had a very very difficult time getting this working in early May. [My problem](https://askubuntu.com/questions/1333453/bridged-networking-in-kvm-qemu-lan-addressed-packets-dropped) turned out to be that my processor was too new for 20.04, and I had to enable HWE so as to have a newer kernel. The only significant difference I see between us, is that I have STP turned off.
matt01 avatar
ph flag
That is interesting. I had a "forced upgrade" as well as I damaged the old processor when upgrading the case & motherboard. I'm now running a Ryzen 7 5800x, which was released recently. So I wonder if there is an incompatibility with Ubuntu 20.04 desktop. Anyway, thank you for taking the time to look at the issue, @DougSmythies .
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