[SOLVED] How to assign same IP to a different interface (VMBR0 change)?

[michaeljd]

Hello,

As shown below, my management interface is 192.168.50.10 on eno1np0, which is an onboard 1GB NIC. Interface enp1s0f0 is a 10GB NIC. What I want to do is make the 10GB NIC my new management interface and give it the same IP VMBR0 currently has. The 1GB NIC will no longer be used once the change is made.

I had (past tense, I completely tanked it) a 2nd PVE server and tried to do this same thing. I went in through the IPMI and virtual KVM and edited the /etc/networking/interfaces file, replaced the current interface with the one I wanted and rebooted. Seemed simple enough. Nope. I completely tanked the machine. Tried "Ifup interfacename" and "ifup vmbr0" and that didn't work. Neither did many reboots.

The machine shown below is my production environment and it can be rebooted but I cannot totally wipe it out. I'm in the process of building a cluster to go on a 10GB backbone, so that's why I'm making these changes.

How can I make this change without losing access to the PVE management GUI and default VM network interface? I am a Linux neophyte, but can follow a tutorial like nobody's business. Thank you in advance.

 

[jsterr]

You can actually just do this in the web-ui by removing the ip from vmbr0 and putting it onto the 10g interface. everything you do in ui is just a preview until you click on "Apply Configuration". Means Edit vmbr0, remove ip, gateway. Edit enp1s0f0 put IP and gateway on it, make sure autostart = yes on enp1s0f0. Click apply configuration.

 

[michaeljd]

Thanks, jsterr. I forgot about the "preview of changes" and having to click apply configuration. I was thinking that as soon as I removed the gateway info from the VMBR0 interface that I'd lose connection to the console.

I will try this tonight, after work. I use my VMs for my work, so can't risk anything going down during the day.

 

[louie1961]

Unless you really need the port on your switch, I personally I wouldn't move it. I would point all your VMs and VLANs to the 10 gig adapter, and leave management on the 1 gig. Management doesn't require a lot of bandwidth, and separating out your VMs from the management access helps improve security. I am not running a cluster, but I have my management access pointed to its own VLAN. My server management interface is on a different IP and different subnet than all of my VMs. In fact I have 6 VLANs and I have VMs or containers on all of them.

 

[michaeljd]

Thank you, louie1961. I know you're right regarding security and that management doesn't use a lot of bandwidth.

My limiting factor is that I'm currently on a flat network, so can only have one network connection to each machine. I have been planning to (and need to) use VLANs at home. I already have them setup on my firewall/DHCP box, but haven't implemented them at the switch/port level because I'll have to re-run some cables and change some other stuff around. "One small change" winds up causing a weekend worth of work.

Always seems that other projects and home life takes precedence...never enough time to get everything done.

 

[louie1961]

I am not a network pro, but why couldn't you have two network connections to your proxmox box if you have two NICs? I think that is quite doable. Again, unless you need the switch port.

 

[michaeljd]

You can actually just do this in the web-ui by removing the ip from vmbr0 and putting it onto the 10g interface. everything you do in ui is just a preview until you click on "Apply Configuration". Means Edit vmbr0, remove ip, gateway. Edit enp1s0f0 put IP and gateway on it, make sure autostart = yes on enp1s0f0. Click apply configuration.

This worked with a small caveat. After putting the IP/GW info on the 10GB NIC, I still had connectivity to the mgmt interface, but lost connectivity to the VMs. I had to then remove the IP info from the 10GB NIC interface, and create a new VMBR0 for the VMs, using the 10GB interface and it's IP info. Connectivity to the VMs popped right back up. Worlds faster than actual HW machines would, especially Windows.

I wish I knew this yesterday before I messed with the /etc/network/interfaces file on the other machine,. But, experience is what you get when you don't get what you expected!

I just wanted to spell out the fix and the details for any n00bs like me that might run into the same issue someday.

Thanks, jsterr!