[SOLVED] Proxmox Host with eth0 has same Mac as vmbr0 - Broken port on Fritzbox

[ajfriesen]

Hey,

I just created a proxmox installation last week with GPU pass through.
Since adding the GPU or any pcie devices changes the ethernet interface name I searched for a way to fix that.

I found this post how to do that and applied this:
Post in thread 'Is there any way to keep the NIC from going down after PCIe change...' https://forum.proxmox.com/threads/i...ing-down-after-pcie-change.137389/post-611497

Now, after some testing and checking of my server will fit in my shelf I discovered that proxmox hi is not available.

I see the eth0 interface but IP address. Double checked the Mac and looks good.

But the vmbr0 interface has the same Mac and got the IP of my proxmox host?

I checked journal and dmesg but did not see anything suspicious.

I think the same Mac address has something to do with proxmox UI and ash and ping not beeping possible. Not 100% ire though.
Might someone of you have an idea?

 

[LnxBil]

But the vmbr0 interface has the same Mac and got the IP of my proxmox host?

That's normal. Unless you want to have PCIe passthrough of your underlying network interface, this is the correct behaviour. Normally, your NIC is attached to the bridge as well as every VM nic attaches to the same bridge, if everything wants to be run natively in your networks - technically it is bridged - and therefore the bridge is needed.

 

[ajfriesen]

Okay, if this is normal I am wondering, why I can not ping, SSH and see the proxmox UI.

I see that the IP address for my host and for my VM are actually listed in my router.

Any idea how to debug this further?

 

[bbgeek17]

Any idea how to debug this further?

Take a look at the output of "ip a" and "cat /etc/network/interfaces". If you don't see anything suspicious - post the output here, preferably as text but photos work as well.

Good luck

---

Blockbridge : Ultra low latency all-NVME shared storage for Proxmox - https://www.blockbridge.com/proxmox

 

[ajfriesen]

Can not SSH into the host right now, so sorry for the picturers. But with PiKVM I can grab a screenshot:








So this had still my old interface name in there.
I changed enp4s0 to eth0 but still does not work after a reboot.

 

[LnxBil]

Please post the output of brctl show vmbr0.

 

[ajfriesen]

Please post the output of brctl show vmbr0.

 

[LnxBil]

So, it is enslaved, that's good.

Can you ping the gateway from your beast? Can you try to run dhclient -v eth0 and report what it shows?

 

[ajfriesen]

So, it is enslaved, that's good.

Can you ping the gateway from your beast? Can you try to run dhclient -v eth0 and report what it shows?

I can not ping the gateway...

Then I thought, lets get physical.
I swapped the cable and suddenly the proxmox host is online and my pikvm is not reachable anymore.

I think on of the ports on the FritzBox is broken.

So much time wasted...

Thank you @LnxBil for getting me there!

Edit:
Yep, the 4th port on the FritzBox is broken.

 

[LnxBil]

Yep, the 4th port on the FritzBox is broken.

AFAIK, ports can be activated/deactivated and also be part of the guest network depending on the configuration. Maybe check the FritzBox setting.

 

[ajfriesen]

AFAIK, ports can be activated/deactivated and also be part of the guest network depending on the configuration. Maybe check the FritzBox setting.

Yeah, I saw this as well and checked.
I can only switch between 1GB or 100MB on that port.
But it is dead.
Even though the LEDs work fine

 

[LnxBil]

That's a pity.