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Re: Bridging Network Connections with libvirt are unreliable

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On Wed, Aug 28, 2024 at 4:06 AM Rainer Dorsch <ml@bokomoko.de> wrote:
>
> Hello,
>
> I have a (for me) weird problem on a bookworm system
>
> rd@h370:~$ inxi -S
> System:
>   Host: h370 Kernel: 6.1.0-23-amd64 arch: x86_64 bits: 64 Desktop: KDE Plasma
>     v: 5.27.5 Distro: Debian GNU/Linux 12 (bookworm)
> rd@h370:~$
>
> It uses bridging network connections with libvirt work unreliable.
>
> I have in /etc/network/interface bridging networks e.g.
>
> iface eno1.2 inet manual
>
> # libvirt VM
> auto br2
> iface br2 inet dhcp
>     # Use the MAC address identified above.
>     hwaddress ether 18:31:bf:52:1b:1c
>     bridge_ports eno1.2
>     # If you want to turn on Spanning Tree Protocol, ask your hosting
>     # provider first as it may conflict with their network.
>     bridge_stp off
>     # If STP is off, set to 0. If STP is on, set to 2 (or greater).
>     bridge_fd 0
>
> to make the interface available for libvirt.
>
> In addition there are non-bridging networks, e.g.
>
> allow-hotplug eno1.4
> iface eno1.4 inet dhcp
>
> All of them share the same physical network but defined separate VLANs.
>
> The full /etc/network/interface file of the machine is here https://
> bokomoko.de/~rd/Debian/interfaces
>
> That works well for many hours or even days, but at some point in time the
> network is suddenly gone, and all network services die.
>
> root@h370:~# ifdown br2
>
> and
>
> root@h370:~# ifup br2
>
> heals the issue immediately. The non-bridging networks don't see the problem.
> The problem occurs independently of libvirt running or not.
>
> In the systemd log, the first entry indicating network problems is that the DNS
> server switches to another interface. But it could easily be a consequence and
> not the cause of the issue:
>
> Aug 28 06:57:54 h370 dhclient[1195]: DHCPREQUEST for 192.168.4.203 on eno1.4
> to 192.168.4.1 port 67
> Aug 28 06:57:54 h370 dhclient[1195]: DHCPACK of 192.168.4.203 from 192.168.4.1
> Aug 28 06:57:54 h370 dnsmasq[2386]: reading /etc/resolv.conf
> Aug 28 06:57:54 h370 dnsmasq[2386]: using nameserver 192.168.4.1#53
> Aug 28 06:57:54 h370 dhclient[1195]: bound to 192.168.4.203 -- renewal in
> 18265 seconds.
>
> As a workaround I could probably write a small script, which pings another
> network host and restarts the br interfaces, but I would prefer to understand
> why the problem occurs at the first place.
>
> Any idea or hint is welcome.

Do you know if MAC Address Randomization is happening on your interfaces?

Jeff

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Thread

Bridging Network Connections with libvirt are unreliable Rainer Dorsch <ml@bokomoko.de> - 2024-08-28 10:10 +0200
  Re: Bridging Network Connections with libvirt are unreliable Tim Woodall <debianuser@woodall.me.uk> - 2024-08-29 20:40 +0200
    Re: Bridging Network Connections with libvirt are unreliable Rainer Dorsch <ml@bokomoko.de> - 2024-08-30 18:50 +0200
  Re: Bridging Network Connections with libvirt are unreliable Jeffrey Walton <noloader@gmail.com> - 2024-08-30 01:20 +0200
    Re: Bridging Network Connections with libvirt are unreliable Rainer Dorsch <ml@bokomoko.de> - 2024-08-30 19:00 +0200

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