Direct connection between VMs?

[AndrewT]

Hi,

I've set up 4 VMs, each running as a (Arista) switch (for network training), and have connected various ports on the VMs to each other via bridges. This is working fine for most things, but LLDP does not seem to be getting from one VM to the next - I'm guessing the bridge is not propagating it. Can I enable this somehow - these are point to point connections between my VMs, so I don't really need or want a bridge in the middle, I want the VMs to think that they are directly connected to each other. I've been through the documentation, and can't see any obvious change to the bridge settings that would help, but I did notice someone describing another type of qemu networking: -net listen,port=... and -net,connect.... I can't see any way to set this up under ProxMox, and 'qm' doesn't appear to support this either (I'm on version 2.3 currently).

Any advice about how to fix this greatly appreciated!

Thanks.

 

[bleomycin]

Sorry i can't be of any help, i'm just interested in this as well.

 

[pirateghost]

Configure a bridge with no ip and not connected to a nic. Connect each vm to that bridge

Sent from my Galaxy Nexus

 

[AndrewT]

Hi,

I think that is how I've set up the bridge - I created a separate bridge for each connection that I wanted to make, with no IP or NIC or anything else, and then attached it to two VMs (they each attach via a virtual e1000).

 

[spirit]

I don't think it's possible without bridge.

-net syntax is old qemu syntax.

qemu create a tap interface on the host, the bridge is used to connect the tap interfaces. I don't known if it's possible to connect 2 tap interfaces together without bridge.

what is LLDP exactly ?

 

[spirit]

seem that is possible to enable lldp frame with kernel 3.2

echo 1 > /sys/class/net/brX/bridge/group_fwd_mask

but it's not available in the current proxmox/redhat kernel

 

[AndrewT]

Spirit, thanks for the pointers on 3.2. I did manage to get '-netdev type=socket...' working and it forwards LLDP between VMs, but I had to run the VMs from the command-line, I haven't found a way to set this up via the web GUI yet.

Andrew.

 

[spirit]

Spirit, thanks for the pointers on 3.2. I did manage to get '-netdev type=socket...' working and it forwards LLDP between VMs, but I had to run the VMs from the command-line, I haven't found a way to set this up via the web GUI yet.

Andrew.

your can add custom command lines to vm config file directly (/etc/pve/qemu-server/vmid.conf) (not via gui).

args: -netdev .....

 

[sookis]

Sorry for bumping old thread but im having this issue. In my search for solutions ive found that linux bridges block lldp-frames (and other). The solutions seems to be to change the group_fwd_mask to 0x4000 but i cant make the changes persist after reboot?