Layer 2: MetalLB shouldn't listen on interfaces which have master

[kvaps]

Is this a bug report or a feature request?:

BUG

What happened:

My nodes have a lot of interfaces, eg. 4 hardware interfaces, 2 bonding, bridge, vlans, and veth interfaces.

When I use arping, I have 8 replies from the metallb speaker. From each interface which passing the traffic.

Eg if you have the next scheme:

   |       |
[eth0]   [eth1]
    \     /
    [bond0]
       |
     [br0]

I will get answer from all of them. That's totally wrong because connectivity will not work if ip address will be associated with interface which have master (eth0, eth1 or bond0)

What you expected to happen:

I expected answer only from br0 interface.

How to reproduce it (as minimally and precisely as possible):

Anything else we need to know?:

Environment:

• MetalLB version:
• Kubernetes version:
• BGP router type/version:
• OS (e.g. from /etc/os-release):
• Kernel (e.g. uname -a):

[kvaps]

Probably we can also exclude interfaces with NOARP flag set

[danderson]

Thanks for the report! This is definitely a bug, in exactly the way you describe.

Unfortunately, getting information about which interfaces are sub-interfaces of others is hard from Go right now, so it's not a 100% trivial fix. There's also a related bug #316 which would allow selecting specific interfaces to listen on, although I still want the default to be automagic.

Thinking...

[kvaps]

Hi @danderson, thanks for quick answer.

I've checked possibilities right now, I think we can use the check for the next directory:

/sys/class/net/<interface>/master

If catalog exists - then ignore interface