Adding many network interfaces to KVM VM

[yavuz]

Hi,

For an arping machine I need a VM with an address in all our subnets. Since I have setup my hv's with separate vmbr's per VLAN I need a VM with lots of interfaces.

Currently I'm getting the following error when adding the 33rd network interface:

Parameter verification failed. (400)

net32: property is not defined in schema and the schema does not allow additional properties

Is this a KVM/QEMU limitation or a Proxmox limitation? Is there a workaround?

 

[dcsapak]

this is a limitation in pve, and there is no easy workaround (besides changing the source code)

would it not be possible to have one vmbr with 'vlan-aware' on and have one network interface configured as trunk in the vm ?

 

[yavuz]

So I tried this but might need a push in the right direction.

1. I added to /etc/network/interfaces on the host:

auto vmbr0
iface vmbr0 inet manual
        bridge_ports bond0
        bridge_stp off
        bridge_fd 0
        bridge_vlan_aware yes
#VLAN aware

2. Brought the interface up on the host:

ifup vmbr0

3. Installed vlan utilities on guest:

apt install vlan

4. Updated network config on guest:

auto ens18
iface ens18 inet manual

auto vlan3043
iface vlan3043 inet static
  address x.x.x.253/24
  gateway x.x.x.1
  vlan_raw_device ens18

5. Assigned the network interface to vmbr0
6. Rebooted guest

Unfortunately this didn't work. What did I miss?

 

[dcsapak]

you also have to add the 'trunks' config to the virtual network interface
in the vm config

net0: xxxxxx,trunks=<vlanid[;vlanid...]>

so for example:

net0: xxxxx,trunks=1;2;3;4;5;6;7;8;9;10;20;30;40;50;60;....

 

[yavuz]

I added trunks=1;2;3;4;5;6;7;8;9;10;20;30;40;50;60;.... (with my own vlan id's ofcourse) to /etc/pve/qemu-server/147.conf, shutdown the guest and powered up. Unfortunately still not working. Any suggestions?

 

[dcsapak]

is that a debian guest? if yes
then maybe this works:

auto eth0.222
iface eth0.222 inet static
address 10.10.10.1
netmask 255.255.255.0
vlan-raw-device eth0

(of course replace the values with your own)

it seems also you had a typo:
you wrote

auto vlan 3043
iface vlan3043 inet static

instead of

auto vlan3043
iface vlan3043 inet static

(notice the space between vlan and 3043)

 

[yavuz]

The space between vlan and 3043 was only on the forum, in my interfaces file it's without a space, I corrected the post above.

Yes, the guest is Debian, I just updated the interfaces file and replaced vlan3043 by ens18.3043, unfortunately still no traffic. Anything else I'm overlooking?

 

[dcsapak]

mhmm what does ip -d addr and ip -d link report ?

 

[yavuz]

See screenshot.

 

[dcsapak]

and on the host?

 

[yavuz]

See attachments. The links which are of importance are ens3f0 and ens4f0 in bond0.

 

[yavuz]

And just to be complete: here is my interfaces file

 

[dcsapak]

looks all correct to me, are the vlan/ip configs correct (also the vlan tags on the switch ports ?)

 

[yavuz]

100% correct, can use the IP addresses if added in the vmbr3043 which is in bond0.3043. Any other ideas / suggestions?

 

[dcsapak]

ah maybe because you already defined the vlan device on the host, the packages do not get forwarded to the vlan aware bridge,
can you try with a vlan which is not already defined on the host?

 

[yavuz]

I just did ifdown vmbr3044 on hv01, and added an IP from vlan 3044 to the guest (ens18.3044), still doesn't work. Do I need to do something else?

By the way this wouldn't solve my initial problem, I'm merely interested in why it doesn't work at the moment

 

[dcsapak]

sorry i am out of ideas, such setups did always work for me, there is something we miss ...

 

[yavuz]

I will solve this another way, thank you for the help.