vmbr0 state UNKNOWN after restarting network

[andrea_it]

Hello,
I just installed proxmox 6.4-14 on Debian 10 on Hetzner dedicated root server.

After many tries I'm finally able to create VM (in routed mode) and everything seems to work fine.

I discovered that when I restart networking service in the host (systemctl restart networking) vmbr0 state become UNKNOWN and consequently all the VM lose the connection with internet.
Is this the expected behaviour? I would expect vmbr comes up instead.

ip a

26: vmbr0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc noqueue state UNKNOWN group default qlen 1000
    link/ether 0a:aa:05:3d:76:65 brd ff:ff:ff:ff:ff:ff
    inet x.y.z.237/32 brd x.y.z.237 scope global vmbr0
       valid_lft forever preferred_lft forever

The only way I found to restore the connection on VM is to edit the network configuration of a VM (i.e. delete mac address / change mac address).

Immediately after this operation vmbr0 state goes to UP as expected.

ip a

31: vmbr0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc noqueue state UP group default qlen 1000
    link/ether 9a:71:a2:8c:88:fb brd ff:ff:ff:ff:ff:ff
     inet x.y.z.237/32 brd x.y.z.237 scope global vmbr0
       valid_lft forever preferred_lft forever

I think it will be rare I have to restart netwroking service on the hosts but in case I'll need to, what should I do?

Is this an intended behaviour? Is it possible to automatically bring up vmbr0 after restarting networking from the host?

Thanks in advance

 

[dylanw]

I just installed proxmox 6.4-14 on Debian 10 on Hetzner dedicated root server.

Note that with a fresh installation, it's recommended to go for Proxmox VE version 7, as Proxmox VE version 6.x will reach "End Of Life" status in July of this year [1].

Would you mind posting your network configuration? cat /etc/network/interfaces

I discovered that when I restart networking service in the host (systemctl restart networking) vmbr0 state become UNKNOWN and consequently all the VM lose the connection with internet.

Was this carried out after making changes to the network configuration? It is recommended to install the package 'ifupdown2' [2] (default in Proxmox VE 7), so that the network configuration and be changed and reloaded in place with the command: ifreload -a. Without this package, after updating the network configuration, a reboot is generally recommended.

[1] https://pve.proxmox.com/pve-docs/pve-admin-guide.html#_frequently_asked_questions_2
[2] https://packages.debian.org/buster/ifupdown2

 

[andrea_it]

After many hours in troubleshooting I finally discovered I simply forgot to make persistent the setting: sysctl net.ipv4.conf.enp7s0.send_redirects

In the end I also reinstalled proxmox 7 given that I thought the problem was with ifupdown2 while it was definitively not.

Thanks for your help