Frequently Asked Questions

Can I have several address pools?

Yes, a given IPAddressPool can allocate multiple IP ranges, and you can have multiple instances, for example:

apiVersion: metallb.io/v1beta1
kind: IPAddressPool
metadata:
  name: first-pool
  namespace: metallb-system
spec:
  addresses:
  - 192.168.10.0/24

apiVersion: metallb.io/v1beta1
kind: IPAddressPool
metadata:
  name: second-pool
  namespace: metallb-system
spec:
  addresses:
  - 192.168.9.1-192.168.9.5
  - fc00:f853:0ccd:e799::/124

You can even specify which pool to draw from using their name. See usage for using annotations to specify which IP pool and address as part of defining your LoadBalancer.

In layer 2 mode, how to specify the host interface for an address pool?

There’s no need: MetalLB automatically listens/advertises on all interfaces. That might sound like a problem, but because of the way ARP/NDP works, only clients on the right network will know to look for the service IP on the network.

NOTE Because of the way layer 2 mode functions, this works with tagged vlans as well. Specify the network and the ip stack figures out the rest.

Can I have the same service advertised via L2 and via BGP?

Yes. This is achieved by simply having an L2Advertisement and a BGPAdvertisement referencing the same IPAddressPool.

In the most simple form:

apiVersion: metallb.io/v1beta1
kind: IPAddressPool
metadata:
  name: first-pool
  namespace: metallb-system
spec:
  addresses:
  - 192.168.10.0/24

apiVersion: metallb.io/v1beta1
kind: BGPAdvertisement
metadata:
  name: bgp
  namespace: metallb-system

apiVersion: metallb.io/v1beta1
kind: L2Advertisement
metadata:
  name: l2
  namespace: metallb-system

Does MetalLB work on OpenStack?

Yes but by default, OpenStack has anti-spoofing protection enabled which prevents the VMs from using any IP that wasn’t configured for them in the OpenStack control plane, such as LoadBalancer IPs from MetalLB. See openstack port set –allowed-address.