Configuring MetalLB BGP peers

Configuring MetalLB BGP peers

As a cluster administrator, you can add, modify, and delete Border Gateway Protocol (BGP) peers. The MetalLB Operator uses the BGP peer custom resources to identify which peers that MetalLB speaker pods contact to start BGP sessions. The peers receive the route advertisements for the load-balancer IP addresses that MetalLB assigns to services.

About the BGP peer custom resource

The fields for the BGP peer custom resource are described in the following table.

Table 1. MetalLB BGP peer custom resource
Field	Type	Description
`metadata.name`	`string`	Specifies the name for the BGP peer custom resource.
`metadata.namespace`	`string`	Specifies the namespace for the BGP peer custom resource.
`spec.myASN`	`integer`	Specifies the Autonomous System number for the local end of the BGP session. Specify the same value in all BGP peer custom resources that you add. The range is `0` to `65535`.
`spec.peerASN`	`integer`	Specifies the Autonomous System number for the remote end of the BGP session. The range is `0` to `65535`.
`spec.peerAddress`	`string`	Specifies the IP address of the peer to contact for establishing the BGP session.
`spec.sourceAddress`	`string`	Optional: Specifies the IP address to use when establishing the BGP session. The value must be an IPv4 address.
`spec.peerPort`	`integer`	Optional: Specifies the network port of the peer to contact for establishing the BGP session. The range is `0` to `16384`.
`spec.holdTime`	`string`	Optional: Specifies the duration for the hold time to propose to the BGP peer. The minimum value is 3 seconds (`3s`). The common units are seconds and minutes, such as `3s`, `1m`, and `5m30s`. To detect path failures more quickly, also configure BFD.
`spec.keepaliveTime`	`string`	Optional: Specifies the maximum interval between sending keep-alive messages to the BGP peer. If you specify this field, you must also specify a value for the `holdTime` field. The specified value must be less than the value for the `holdTime` field.
`spec.routerID`	`string`	Optional: Specifies the router ID to advertise to the BGP peer. If you specify this field, you must specify the same value in every BGP peer custom resource that you add.
`spec.password`	`string`	Optional: Specifies the MD5 password to send to the peer for routers that enforce TCP MD5 authenticated BGP sessions.
`spec.bfdProfile`	`string`	Optional: Specifies the name of a BFD profile.
`spec.nodeSelectors`	`object[]`	Optional: Specifies a selector, using match expressions and match labels, to control which nodes can connect to the BGP peer.
`spec.ebgpMultiHop`	`boolean`	Optional: Specifies that the BGP peer is multiple network hops away. If the BGP peer is not directly connected to the same network, the speaker cannot establish a BGP session unless this field is set to `true`. This field applies to external BGP. External BGP is the term that is used to describe when a BGP peer belongs to a different Autonomous System.

Configuring a BGP peer

As a cluster administrator, you can add a BGP peer custom resource to exchange routing information with network routers and advertise the IP addresses for services.

Prerequisites

Install the OpenShift CLI (oc).
Log in as a user with cluster-admin privileges.
Configure a MetalLB address pool that specifies bgp for the spec.protocol field.

Procedure

Create a file, such as bgppeer.yaml, with content like the following example:

apiVersion: metallb.io/v1beta1
kind: BGPPeer
metadata:
  namespace: metallb-system
  name: doc-example-peer
spec:
  peerAddress: 10.0.0.1
  peerASN: 64501
  myASN: 64500
  routerID: 10.10.10.10

Apply the configuration for the BGP peer:
```
$ oc apply -f bgppeer.yaml
```

Next steps

Configure a MetalLB address pool that specifies bgp for the spec.protocol field.

Example BGP peer configurations

Example: Limit which nodes connect to a BGP peer

You can specify the node selectors field to control which nodes can connect to a BGP peer.

apiVersion: metallb.io/v1beta1
kind: BGPPeer
metadata:
  name: doc-example-nodesel
  namespace: metallb-system
spec:
  peerAddress: 10.0.20.1
  peerASN: 64501
  myASN: 64500
  nodeSelectors:
  - matchExpressions:
    - key: kubernetes.io/hostname
      operator: In
      values: [compute-1.example.com, compute-2.example.com]

Example: Specify a BFD profile for a BGP peer

You can specify a BFD profile to associate with BGP peers. BFD compliments BGP by providing more rapid detection of communication failures between peers than BGP alone.

apiVersion: metallb.io/v1beta1
kind: BGPPeer
metadata:
  name: doc-example-peer-bfd
  namespace: metallb-system
spec:
  peerAddress: 10.0.20.1
  peerASN: 64501
  myASN: 64500
  holdTime: "10s"
  bfdProfile: doc-example-bfd-profile-full

Example: Specify BGP peers for dual-stack networking

To support dual-stack networking, add one BGP peer custom resource for IPv4 and one BGP peer custom resource for IPv6.

apiVersion: metallb.io/v1beta1
kind: BGPPeer
metadata:
  name: doc-example-dual-stack-ipv4
  namespace: metallb-system
spec:
  peerAddress: 10.0.20.1
  peerASN: 64500
  myASN: 64500
---
apiVersion: metallb.io/v1beta1
kind: BGPPeer
metadata:
  name: doc-example-dual-stack-ipv6
  namespace: metallb-system
spec:
  peerAddress: 2620:52:0:88::104
  peerASN: 64500
  myASN: 64500

Next steps

Configuring services to use MetalLB